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Reading and Writing Config Files

ConfigObj 4 Introduction and Reference

:Authors: Michael Foord, Nicola Larosa
:Version: ConfigObj 4.3.2
:Date: 2006/06/04
:Homepage: `ConfigObj Homepage`_
:Sourceforge: Sourceforge_
:Development: `SVN Repository`_
:License: `BSD License`_
:Support: `Mailing List`_

.. _Mailing List: http://lists.sourceforge.net/lists/listinfo/configobj-develop .. _SVN Repository: http://svn.pythonutils.python-hosting.com

.. meta::

:description: ConfigObj - a Python module for easy reading and writing of

config files.
:keywords: python, script, module, config, configuration, data, persistence,

developer, configparser

.. contents:: ConfigObj Manual
.. sectnum::

Introduction

**ConfigObj** is a simple but powerful config file reader and writer: an ini file round tripper. Its main feature is that it is very easy to use, with a straightforward programmer's interface and a simple syntax for config files. It has lots of other features though :

.. sidebar:: ConfigObj in the Real World

**ConfigObj** is now used as the config file parser for `Bazaar <http://bazaar-ng.org>`_.

Bazaar is the Python distributed {acro;VCS;Version Control System}. ConfigObj is used to read ``bazaar.conf`` and ``branches.conf``.

Other projects that use **ConfigObj** include :

        A new web application version of `Planet <http://www.planetplanet.org/>`_, 
        the web aggregator.
        BrainSTAT is a project with the ultimate goal to produce a
        platform-independent python environment for the analysis of brain
        imaging data.

Gruik is a free software network packet sniffer.

        **ConfigObj** will be used for reading Turbogears config files, from
        version 1.1.
  • Nested sections (subsections), to any level
  • List values
  • Multiple line values
  • String interpolation (substitution)
  • Integrated with a powerful validation system
    • including automatic type checking/conversion
    • repeated sections
    • and allowing default values
  • All comments in the file are preserved
  • The order of keys/sections is preserved
  • No external dependencies
  • Full Unicode support
  • A powerful ``unrepr`` mode for storing basic datatypes

ConfigObj has a barrage of doctests [#]_ built into it, testing almost every feature. Run ``python configobj_test.py -v`` to see them in action.

For support and bug reports please use the ConfigObj `Mailing List`_.

.. _ConfigObj for Data Persistence: http://www.voidspace.org.uk/python/articles/configobj_for_data_persistence.shtml .. _ConfigPersist.py: http://www.voidspace.org.uk/python/configpersist.html

Downloading

The current version is **4.3.2**, dated 4th June 2006. ConfigObj 4 is now stable. We still expect to pick up a few bugs along the way though [#]_. {sm;:-)}

You can get ConfigObj in the following ways :

Files

  • configobj.py_ from Voidspace

ConfigObj has no external dependencies. This file is sufficient to access all the functionality except Validation_.

  • configobj.zip_ from Voidspace

This also contains validate.py_ , the `API Docs`_ and `this document`_.

  • The latest development version can be obtained from the `Subversion Repository`_.
  • validate.py_ from Voidspace
  • You can also download configobj.zip from Sourceforge_

Documentation

configobj.zip contains `this document`_ and full `API Docs`_, generated by the EpyDoc_ program.

  • You can view `this document`_ online as the `ConfigObj Homepage`_.
  • You can also browse the `API Docs`_ online.

Pythonutils

ConfigObj is also part of the Pythonutils_ set of modules. This contains various other useful modules, and is required by many of the `Voidspace Python Projects`_.

Development Version

It is sometimes possible to get the latest development version of ConfigObj from the `Subversion Repository <http://svn.pythonutils.python-hosting.com/trunk/pythonutils/>`_.

.. _configobj.py: http://www.voidspace.org.uk/cgi-bin/voidspace/downman.py?file=configobj.py .. _configobj.zip: http://www.voidspace.org.uk/cgi-bin/voidspace/downman.py?file=configobj-4.3.2.zip .. _validate.py: http://www.voidspace.org.uk/cgi-bin/voidspace/downman.py?file=validate.py .. _API Docs: http://www.voidspace.org.uk/python/configobj-api/ .. _this document:
.. _configobj homepage: http://www.voidspace.org.uk/python/configobj.html .. _Sourceforge: http://sourceforge.net/projects/configobj .. _EpyDoc: http://epydoc.sourceforge.net .. _pythonutils: http://www.voidspace.org.uk/python/pythonutils.html .. _Voidspace Python Projects: http://www.voidspace.org.uk/python

Getting Started

The outstanding feature of using ConfigObj is simplicity. Most functions can be performed with single line commands.

Reading a Config File

The normal way to read a config file, is to give ConfigObj the filename :

.. raw:: html

{+coloring}

from configobj import ConfigObj
config = ConfigObj(filename)

{-coloring}

You can also pass the config file in as a list of lines, or a ``StringIO`` instance, so it doesn't matter where your config data comes from.

You can then access members of your config file as a dictionary. Subsections will also be dictionaries.

.. raw:: html

{+coloring}

from configobj import ConfigObj
config = ConfigObj(filename)
#
value1 = config['keyword1']
value2 = config['keyword2']
#
section1 = config['section1']
value3 = section1['keyword3']
value4 = section1['keyword4']
#
# you could also write
value3 = config['section1']['keyword3'] value4 = config['section1']['keyword4']

{-coloring}

Writing a Config File

Creating a new config file is just as easy as reading one. You can specify a filename when you create the ConfigObj, or do it later [#]_.

If you don't set a filename, then the ``write`` method will return a list of lines instead of writing to file. See the write_ method for more details.

Here we show creating an empty ConfigObj, setting a filename and some values, and then writing to file :

.. raw:: html

{+coloring}

from configobj import ConfigObj
config = ConfigObj()
config.filename = filename
#
config['keyword1'] = value1
config['keyword2'] = value2
#
config['section1'] = {}
config['section1']['keyword3'] = value3 config['section1']['keyword4'] = value4 #
section2 = {

        'keyword5': value5,
        'keyword6': value6,
        'sub-section': {
            'keyword7': value7
            }

}
config['section2'] = section2
#
config['section3'] = {}
config['section3']['keyword 8'] = [value8, value9, value10] config['section3']['keyword 9'] = [value11, value12, value13] #
config.write()

{-coloring}

.. caution::

Keywords and section names can only be strings [#]_. Attempting to set anything else will raise a ``ValueError``.

Config Files

The config files that ConfigObj will read and write are based on the 'INI' format. This means it will read and write files created for ``ConfigParser`` [#]_.

Keywords and values are separated by an ``'='``, and section markers are between square brackets. Keywords, values, and section names can be surrounded by single or double quotes. Indentation is not significant, but can be preserved.

Subsections are indicated by repeating the square brackets in the section marker. You nest levels by using more brackets.

You can have list values by separating items with a comma, and values spanning multiple lines by using triple quotes (single or double).

For full details on all these see `the config file format`_. Here's an example to illustrate : ::

# This is the 'initial_comment'
# Which may be several lines
keyword1 = value1
'keyword 2' = 'value 2'

[ "section 1" ]
# This comment goes with keyword 3
keyword 3 = value 3
'keyword 4' = value4, value 5, 'value 6'

        [[ sub-section ]]    # an inline comment
        # sub-section is inside "section 1"
        'keyword 5' = 'value 7'
        'keyword 6' = '''A multiline value,

that spans more than one line :-)
The line breaks are included in the value.'''

            [[[ sub-sub-section ]]]
            # sub-sub-section is in 'sub-section'
            # which is in 'section 1'
            'keyword 7' = 'value 8'

[section 2] # an inline comment
keyword8 = "value 9"
keyword9 = value10 # an inline comment # The 'final_comment'
# Which also may be several lines

ConfigObj specifications

.. raw:: html

{+coloring}

config = ConfigObj(infile=None, options=None, **keywargs)

{-coloring}

infile

You don't need to specify an infile. If you omit it, an empty ConfigObj will be created. ``infile`` can be :

  • Nothing. In which case the ``filename`` attribute of your ConfigObj will be ``None``. You can set a filename at any time.
  • A filename. What happens if the file doesn't already exist is determined by the options_ ``file_error`` and ``create_empty``. The filename will be preserved as the ``filename`` attribute. This can be changed at any time.
  • A list of lines. Any trailing newlines will be removed from the lines. The ``filename`` attribute of your ConfigObj will be ``None``.
  • A ``StringIO`` instance or file object, or any object with a ``read`` method. The ``filename`` attribute of your ConfigObj will be ``None`` [#]_.
  • A dictionary. You can initialise a ConfigObj from a dictionary [#]_. The ``filename`` attribute of your ConfigObj will be ``None``. All keys must be strings. In this case, the order of values and sections is arbitrary.

options

There are various options that control the way ConfigObj behaves. They can be passed in as a dictionary of options, or as keyword arguments. Explicit keyword arguments override the dictionary.

All of the options are available as attributes after the config file has been parsed.

ConfigObj has the following options (with the default values shown) :

  • 'raise_errors': ``False``

When parsing, it is possible that the config file will be badly formed. The default is to parse the whole file and raise a single error at the end. You can set ``raise_errors = True`` to have errors raised immediately. See the exceptions_ section for more details.

Altering this value after initial parsing has no effect.

  • 'list_values': ``True``

If ``True`` (the default) then list values are possible. If ``False``, the values are not parsed for lists.

        If ``list_values = False`` then single line values are not quoted or
        unquoted when reading and writing.

Changing this value affects whether single line values will be quoted or not when writing.

  • 'create_empty': ``False``

If this value is ``True`` and the file specified by ``infile`` doesn't exist, ConfigObj will create an empty file. This can be a useful test that the filename makes sense: an impossible filename will cause an error.

Altering this value after initial parsing has no effect.

  • 'file_error': ``False``

If this value is ``True`` and the file specified by ``infile`` doesn't exist, ConfigObj will raise an ``IOError``.

Altering this value after initial parsing has no effect.

  • 'interpolation': ``True``

Whether string interpolation is switched on or not. It is on (``True``) by default.

You can set this attribute to change whether string interpolation is done when values are fetched. See the interpolation_ section for more details.

  • 'configspec': ``None``

If you want to use the validation system, you supply a configspec. This is effectively a type of config file that specifies a check for each member. This check can be used to do type conversion as well as check that the value is within your required parameters.

You provide a configspec in the same way as you do the initial file: a filename, or list of lines, etc. See the validation_ section for full details on how to use the system.

When parsed, every section has a ``configspec`` with a dictionary of configspec checks for that section.

  • 'stringify': ``True``

If you use the validation scheme, it can do type checking and conversion for you. This means you may want to set members to integers, or other non-string values.

If 'stringify' is set to ``True`` (default) then non-string values will be converted to strings when you write the config file. The validation_ process converts values from strings to the required type.

If 'stringify' is set to ``False``, attempting to set a member to a non-string value [#]_ will raise a ``TypeError`` (no type conversion is done by validation).

  • 'indent_type': ``' '``

Indentation is not significant; it can however be present in the output config. Allowable values are: ``''`` (no indentation), ``' '`` (indentation with spaces, fixed at four per level), or ``'\t'`` (indentation with tabs, one tab per level).

If this option is not specified, and the ConfigObj is initialised with a dictionary, the indentation used in the output is the default one, that is, spaces.

If this option is not specified, and the ConfigObj is initialised with a list of lines or a file, the indentation used in the first indented line is selected and used in all output lines. If no input line is indented, no output line will be either.

If this option is specified, the option value is used in the output config, overriding the type of indentation in the input config (if any).

  • 'encoding': ``None``

By default **ConfigObj** does not decode the file/strings you pass it into Unicode [#]_. If you want your config file as Unicode (keys and members) you need to provide an encoding to decode the file with. This encoding will also be used to encode the config file when writing.

You can change the encoding attribute at any time.

Any characters in your strings that can't be encoded with the specified encoding will raise a ``UnicodeEncodeError``.

.. note::

        ``UTF16`` encoded files will automatically be detected and decoded,
        even if ``encoding`` is ``None``.
        
        This is because it is a 16-bit encoding, and ConfigObj will mangle it
        (split characters on byte boundaries) if it parses it without decoding.
  • 'default_encoding': ``None``

When using the ``write`` method, **ConfigObj** uses the ``encoding`` attribute to encode the Unicode strings. If any members (or keys) have been set as byte strings instead of Unicode, these must first be decoded to Unicode before outputting in the specified encoding.

``default_encoding``, if specified, is the encoding used to decode byte strings in the **ConfigObj** before writing. If this is ``None``, then the Python default encoding (``sys.defaultencoding`` - usually ASCII) is used.

For most Western European users, a value of ``latin-1`` is sensible.

``default_encoding`` is only used if an ``encoding`` is specified.

Any characters in byte-strings that can't be decoded using the ``default_encoding`` will raise a ``UnicodeDecodeError``.

  • 'unrepr': ``False``

The ``unrepr`` option reads and writes files in a different mode. This allows you to store and retrieve the basic Python data-types using config files.

This uses Python syntax for lists and quoting. See `unrepr mode`_ for the full details.

  • 'write_empty_values': ``False``

If ``write_empty_values`` is ``True``, empty strings are written as empty values. See `Empty Values`_ for more details.

Methods

The ConfigObj is a subclass of an object called ``Section``, which is itself a subclass of ``dict``, the builtin dictionary type. This means it also has **all** the normal dictionary methods.

In addition, the following `Section Methods`_ may be useful :

  • encode
  • decode
  • walk
  • merge
  • dict
  • as_bool
  • as_float
  • as_int

Read about Sections_ for details of all the methods.

.. hint::

The merge method of sections is a recursive update.

You can use this to merge sections, or even whole ConfigObjs, into each other.

You would typically use this to create a default ConfigObj and then merge in user settings. This way users only need to specify values that are different from the default.

The public methods available on ConfigObj are :

  • 'write'
  • 'validate'

write

::

write(file_object=None)

This method writes the current ConfigObj and takes a single, optional argument [#]_.

If you pass in a file like object to the ``write`` method, the config file will be written to this. (The only method of this object that is used is its ``write`` method, so a ``StringIO`` instance, or any other file like object will work.)

Otherwise, the behaviour of this method depends on the ``filename`` attribute of the ConfigObj.

``filename``

ConfigObj will write the configuration to the file specified.

``None``

``write`` returns a list of lines. (Not ``'\n'`` terminated)

First the 'initial_comment' is written, then the config file, followed by the 'final_comment'. Comment lines and inline comments are written with each key/value.

validate

::

validate(validator, preserve_errors=False, copy=False)

.. raw:: html

{+coloring}

# filename is the config file
# filename2 is the configspec
# (which could also be hardcoded into your program) config = ConfigObj(filename, configspec=filename2) #
from validate import Validator
val = Validator()
test = config.validate(val)
if test == True:

print 'Succeeded.'

{-coloring}

The validate method uses the `validate <http://www.voidspace.org.uk/python/validate.html>`__ module to do the validation.

This method validates the ConfigObj against the configspec. By doing type conversion as well, it can abstract away the config file altogether and present the config data to your application (in the types it expects it to be).

If the ``configspec`` attribute of the ConfigObj is ``None``, it raises a ``ValueError``.

If the stringify_ attribute is set, this process will convert values to the type defined in the configspec.

The validate method uses checks specified in the configspec and defined in the ``Validator`` object. It is very easy to extend.

The configspec looks like the config file, but instead of the value, you specify the check (and any default value). See the validation_ section for details.

.. hint::

The system of configspecs can seem confusing at first, but is actually quite simple and powerful. For a concrete example of how to use it, you may find this blog entry helpful :
`Transforming Values with ConfigObj <http://www.voidspace.org.uk/python/weblog/arch_d7_2006_03_04.shtml#e257>`_.

There is also a module to assist in auto-generating configspecs called ConfigPersist.py_. Its use is explained in `ConfigObj for Data Persistence`_.

The ``copy`` parameter fills in missing values from the configspec (default values), without marking the values as defaults. It also causes comments to be copied from the configspec into the config file. This allows you to use a configspec to create default config files. (Normally default values aren't written out by the ``write`` method.)

As of ConfigObj 4.3.0 you can also pass in a ConfigObj instance as your configspec. This is especially useful if you need to specify the encoding of your configspec file. When you read your configspec file, you must specify ``list_values=False``.

.. raw:: html

{+coloring}
from configobj import ConfigObj
configspec = ConfigObj(configspecfilename, encoding='UTF8',

list_values=False)
config = ConfigObj(filename, configspec=configspec) {-coloring}

Return Value
############

By default, the validate method either returns ``True`` (everything passed) or a dictionary of ``True``/``False`` representing pass/fail. The dictionary follows the structure of the ConfigObj.

If a whole section passes then it is replaced with the value ``True``. If a whole section fails, then it is replaced with the value ``False``.

If a value is missing, and there is no default in the check, then the check automatically fails.

The ``validate`` method takes an optional keyword argument ``preserve_errors``. If you set this to ``True``, instead of getting ``False`` for failed checks you get the actual error object from the **validate** module. This usually contains useful information about why the check failed.

See the `flatten_errors`_ function for how to turn your results dictionary into a useful list of error messages.

Even if ``preserve_errors`` is ``True``, missing keys or sections will still be represented by a ``False`` in the results dictionary.

Mentioning Default Values
#########################

In the check in your configspec, you can specify a default to be used - by using the ``default`` keyword. E.g. ::

key1 = integer(0, 30, default=15)
key2 = integer(default=15)
key3 = boolean(default=True)
key4 = option('Hello', 'Goodbye', 'Not Today', default='Not Today')

If the configspec check supplies a default and the value is missing in the config, then the default will be set in your ConfigObj. (It is still passed to the ``Validator`` so that type conversion can be done: this means the default value must still pass the check.)

ConfigObj keeps a record of which values come from defaults, using the ``defaults`` attribute of sections_. Any key in this list isn't written out by the ``write`` method. If a key is set from outside (even to the same value) then it is removed from the ``defaults`` list.

.. note:

Even if all the keys in a section are in the defaults list, the section marker is still written out.

There is additionally a special case default value of ``None``. If you set the default value to ``None`` and the value is missing, the value will always be set to ``None``. As the other checks don't return ``None`` (unless you implement your own that do), you can tell that this value came from a default value (and was missing from the config file). It allows an easy way of implementing optional values. Simply check (and ignore) members that are set to ``None``.

.. note::

If stringify_ is ``False`` then ``default=None`` returns ``''`` instead of ``None``. This is because setting a value to a non-string raises an error if stringify is unset.

The default value can be a list. See `List Values`_ for the way to do this.

Writing invalid default values is a guaranteed way of confusing your users. Default values **must** pass the check.

Mentioning Repeated Sections
############################

In the configspec it is possible to cause every sub-section in a section to be validated using the same configspec. You do this with a section in the configspec called ``__many__``. Every sub-section in that section has the ``__many__`` configspec applied to it (without you having to explicitly name them in advance).

If you define a ``__many__`` type section it must the only sub-section in that section. Having a ``__many__`` and other sub-sections defined in the same section will raise a ``RepeatSectionError``.

Your ``__many__`` section can have nested subsections, which can also include ``__many__`` type sections.

See `Repeated Sections`_ for examples.

Mentioning SimpleVal
####################

If you just want to check if all members are present, then you can use the ``SimpleVal`` object that comes with ConfigObj. It only fails members if they are missing.

Write a configspec that has all the members you want to check for, but set every section to ``''``.

.. raw:: html

{+coloring}

val = SimpleVal()
test = config.validate(val)
if test is True:

print 'Succeeded.'

{-coloring}

Mentioning copy Mode
####################

As discussed in `Mentioning Default Values`_, you can use a configspec to supply default values. These are marked in the ConfigObj instance as defaults, and not written out by the ``write`` mode. This means that your users only need to supply values that are different from the defaults.

This can be inconvenient if you do want to write out the default values, for example to write out a default config file.

If you set ``copy=True`` when you call validate, then no values are marked as defaults. In addition, all comments from the configspec are copied into your ConfigObj instance. You can then call ``write`` to create your config file.

There is a limitation with this. In order to allow Interpolation_ to work within configspecs, ``DEFAULT`` sections are not processed by validation; even in copy mode.

Attributes

A ConfigObj has the following attributes :

  • indent_type
  • interpolate
  • stringify
  • BOM
  • initial_comment
  • final_comment
  • list_values
  • encoding
  • default_encoding
  • unrepr
  • write_empty_values

.. note::

This doesn't include comments, inline_comments, defaults, or configspec. These are actually attributes of Sections_.

It also has the following attributes as a result of parsing. They correspond to options_ when the ConfigObj was created, but changing them has no effect.

  • raise_errors
  • create_empty
  • file_error

interpolate

ConfigObj can perform string interpolation in a similar way to ``ConfigParser``. See the interpolation_ section for full details.

If ``interpolate`` is set to ``False``, then interpolation is not done when you fetch values.

stringify

If this attribute is set (``True``) then the validate_ method changes the values in the ConfigObj. These are turned back into strings when write_ is called.

If stringify is unset (``False``) then attempting to set a value to a non string (or a list of strings) will raise a ``TypeError``.

BOM

If the initial config file started with the UTF8 Unicode signature (known slightly incorrectly as the {acro;BOM;Byte Order Mark}), or the UTF16 BOM, then this attribute is set to ``True``. Otherwise it is ``False``.

If it is set to ``True`` when ``write`` is called then, if ``encoding`` is set to ``None`` or to ``utf_8`` (and variants) a UTF BOM will be written.

For UTF16 encodings, a BOM is always written.

initial_comment

This is a list of lines. If the ConfigObj is created from an existing file, it will contain any lines of comments before the start of the members.

If you create a new ConfigObj, this will be an empty list.

The write method puts these lines before it starts writing out the members.

final_comment

This is a list of lines. If the ConfigObj is created from an existing file, it will contain any lines of comments after the last member.

If you create a new ConfigObj, this will be an empty list.

The ``write`` method puts these lines after it finishes writing out the members.

list_values

This attribute is ``True`` or ``False``. If set to ``False`` then values are not parsed for list values. In addition single line values are not unquoted.

This allows you to do your own parsing of values. It exists primarily to support the reading of the configspec_ - but has other use cases.

For example you could use the ``LineParser`` from the `listquote module <http://www.voidspace.org.uk/python/listquote.html#lineparser>`_ to read values for nested lists.

Single line values aren't quoted when writing - but multiline values are handled as normal.

.. caution::

Because values aren't quoted, leading or trailing whitespace can be

lost.

This behaviour was changed in version 4.0.1.

        Prior to this, single line values might have been quoted; even with
        ``list_values=False``. This means that files written by **ConfigObj**
        could now be incompatible - and need the quotes removing by hand.

encoding

This is the encoding used to encode the output, when you call ``write``. It must be a valid encoding `recognised by Python <http://docs.python.org/lib/standard-encodings.html>`_.

If this value is ``None`` then no encoding is done when ``write`` is called.

default_encoding

If encoding is set, any byte-strings in your ConfigObj instance (keys or members) will first be decoded to Unicode using the encoding specified by the ``default_encoding`` attribute. This ensures that the output is in the encoding specified.

If this value is ``None`` then ``sys.defaultencoding`` is used instead.

unrepr

Another boolean value. If this is set, then ``repr(value)`` is used to write values. This writes values in a slightly different way to the normal ConfigObj file syntax.

This preserves basic Python data-types when read back in. See `unrepr mode`_ for more details.

write_empty_values

Also boolean. If set, values that are an empty string (``''``) are written as empty values. See `Empty Values`_ for more details.

The Config File Format

You saw an example config file in the `Config Files`_ section. Here is a fuller specification of the config files used and created by ConfigObj.

The basic pattern for keywords is : ::

# comment line
# comment line
keyword = value # inline comment

Both keyword and value can optionally be surrounded in quotes. The equals sign is the only valid divider.

Values can have comments on the lines above them, and an inline comment after them. This, of course, is optional. See the comments_ section for details.

If a keyword or value starts or ends with whitespace, or contains a quote mark or comma, then it should be surrounded by quotes. Quotes are not necessary if whitespace is surrounded by non-whitespace.

Values can also be lists. Lists are comma separated. You indicate a single member list by a trailing comma. An empty list is shown by a single comma : ::

keyword1 = value1, value2, value3
keyword2 = value1, # a single member list keyword3 = , # an empty list

Values that contain line breaks (multi-line values) can be surrounded by triple quotes. These can also be used if a value contains both types of quotes. List members cannot be surrounded by triple quotes : ::

keyword1 = ''' A multi line value
on several
lines''' # with a comment
keyword2 = '''I won't be "afraid".''' #
keyword3 = """ A multi line value
on several
lines""" # with a comment
keyword4 = """I won't be "afraid"."""

.. warning::

There is no way of safely quoting values that contain both types of triple quotes.

A line that starts with a '#', possibly preceded by whitespace, is a comment.

New sections are indicated by a section marker line. That is the section name in square brackets. Whitespace around the section name is ignored. The name can be quoted with single or double quotes. The marker can have comments before it and an inline comment after it : ::

# The First Section
[ section name 1 ] # first section
keyword1 = value1

# The Second Section
[ "section name 2" ] # second section keyword2 = value2

Any subsections (sections that are inside the current section) are designated by repeating the square brackets before and after the section name. The number of square brackets represents the nesting level of the sub-section. Square brackets may be separated by whitespace; such whitespace, however, will not be present in the output config written by the ``write`` method.

Indentation is not significant, but can be preserved. See the description of the ``indent_type`` option, in the `ConfigObj specifications`_ chapter, for the details.

A NestingError will be raised if the number of the opening and the closing brackets in a section marker is not the same, or if a sub-section's nesting level is greater than the nesting level of it parent plus one.

In the outer section, single values can only appear before any sub-section. Otherwise they will belong to the sub-section immediately before them. ::

# initial comment
keyword1 = value1
keyword2 = value2

[section 1]
keyword1 = value1
keyword2 = value2

        [[sub-section]]
        # this is in section 1
        keyword1 = value1
        keyword2 = value2

            [[[nested section]]]
            # this is in sub section
            keyword1 = value1
            keyword2 = value2

        [[sub-section2]]
        # this is in section 1 again
        keyword1 = value1
        keyword2 = value2

[[sub-section3]]
# this is also in section 1, indentation is misleading here keyword1 = value1
keyword2 = value2

# final comment

When parsed, the above config file produces the following data structure :

.. raw:: html

{+coloring}

ConfigObj({

        'keyword1': 'value1',
        'keyword2': 'value2',
        'section 1': {
            'keyword1': 'value1',
            'keyword2': 'value2',
            'sub-section': {
                'keyword1': 'value1',
                'keyword2': 'value2',
                'nested section': {
                    'keyword1': 'value1',
                    'keyword2': 'value2',
                },
            },
            'sub-section2': {
                'keyword1': 'value1',
                'keyword2': 'value2',
            },
            'sub-section3': {
                'keyword1': 'value1',
                'keyword2': 'value2',
            },
        },

})

{-coloring}

Sections are ordered: note how the structure of the resulting ConfigObj is in the same order as the original file.

.. note::

In ConfigObj 4.3.0 empty values became valid syntax. They are read as the empty string. There is also an option/attribute (``write_empty_values``) to allow the writing of these.

This is mainly to support 'legacy' config files, written from other applications. This is documented under `Empty Values`_.

`unrepr mode`_ introduces another syntax variation, used for storing basic Python datatypes in config files. {sm;:-)}

Sections

Every section in a ConfigObj has certain properties. The ConfigObj itself also has these properties, because it too is a section (sometimes called the root section).

``Section`` is a subclass of the standard new-class dictionary, therefore it has **all** the methods of a normal dictionary. This means you can ``update`` and ``clear`` sections.

.. note::

You create a new section by assigning a member to be a dictionary.

The new ``Section`` is created from the dictionary, but isn't the same thing as the dictionary. (So references to the dictionary you use to create the section aren't references to the new section).

Note the following.

.. raw:: html

{+coloring}

        config = ConfigObj()
        vals = {'key1': 'value 1', 
                'key2': 'value 2'
               }
        config['vals'] = vals
        config['vals'] == vals
        True
        config['vals'] is vals
        False
        
        {-coloring}

If you now change ``vals``, the changes won't be reflected in ``config['vals']``.

A section is ordered, following its ``scalars`` and ``sections`` attributes documented below. This means that the following dictionary attributes return their results in order.

  • '__iter__'

More commonly known as ``for member in section:``.

  • '__repr__' and '__str__'

Any time you print or display the ConfigObj.

  • 'items'
  • 'iteritems'
  • 'iterkeys'
  • 'itervalues'
  • 'keys'
  • 'popitem'
  • 'values'

Section Attributes

  • main

A reference to the main ConfigObj.

  • parent

A reference to the 'parent' section, the section that this section is a member of.

On the ConfigObj this attribute is a reference to itself. You can use this to walk up the sections, stopping when ``section.parent is section``.

  • depth

The nesting level of the current section.

If you create a new ConfigObj and add sections, 1 will be added to the depth level between sections.

  • defaults

This attribute is a list of scalars that came from default values. Values that came from defaults aren't written out by the ``write`` method. Setting any of these values in the section removes them from the defaults list.

  • scalars, sections

These attributes are normal lists, representing the order that members, single values and subsections appear in the section. The order will either be the order of the original config file, or the order that you added members.

The order of members in this lists is the order that ``write`` creates in the config file. The ``scalars`` list is output before the ``sections`` list.

Adding or removing members also alters these lists. You can manipulate the lists directly to alter the order of members.

.. warning::

        If you alter the ``scalars``, ``sections``, or ``defaults`` attributes
        so that they no longer reflect the contents of the section, you will
        break your ConfigObj.

See also the ``rename`` method.

  • comments

This is a dictionary of comments associated with each member. Each entry is a list of lines. These lines are written out before the member.

  • inline_comments

This is another dictionary of comments associated with each member. Each entry is a string that is put inline with the member.

  • configspec

The configspec attribute is a dictionary mapping scalars to checks. A check defines the expected type and possibly the allowed values for a member.

The configspec has the same format as a config file, but instead of values it has a specification for the value (which may include a default value). The validate_ method uses it to check the config file makes sense. If a configspec is passed in when the ConfigObj is created, then it is parsed and broken up to become the ``configspec`` attribute of each section.

If you didn't pass in a configspec, this attribute will be ``None`` on the root section (the main ConfigObj).

You can set the configspec attribute directly on a section.

See the validation_ section for full details of how to write configspecs.

Section Methods

  • **dict**

This method takes no arguments. It returns a deep copy of the section as a dictionary. All subsections will also be dictionaries, and list values will be copies, rather than references to the original [#]_.

  • **rename**

``rename(oldkey, newkey)``

This method renames a key, without affecting its position in the sequence.

It is mainly implemented for the ``encode`` and ``decode`` methods, which provide some Unicode support.

  • **merge**

``merge(indict)``

This method is a recursive update method. It allows you to merge two config files together.

You would typically use this to create a default ConfigObj and then merge in user settings. This way users only need to specify values that are different from the default.

For example :

.. raw:: html

{+coloring}

        # def_cfg contains your default config settings
        # user_cfg contains the user settings
        cfg = ConfigObj(def_cfg)
        usr = ConfigObj(user_cfg)
        #
        cfg.merge(usr)
        
        """
        cfg now contains a combination of the default settings and the user
        settings.
        
        The user settings will have overwritten any of the default ones.
        """
    
        {-coloring}
  • **walk**

This method can be used to transform values and names. See `walking a section`_ for examples and explanation.

  • **decode**

``decode(encoding)``

This method decodes names and values into Unicode objects, using the supplied encoding.

  • **encode**

``encode(encoding)``

This method is the opposite of ``decode`` {sm;:!:}.

It encodes names and values using the supplied encoding. If any of your names/values are strings rather than Unicode, Python will have to do an implicit decode first. (This method uses ``sys.defaultencoding`` for implicit decodes.)

  • **as_bool**

``as_bool(key)``

Returns ``True`` if the key contains a string that represents ``True``, or is the ``True`` object.

Returns ``False`` if the key contains a string that represents ``False``, or is the ``False`` object.

Raises a ``ValueError`` if the key contains anything else.

Strings that represent ``True`` are (not case sensitive) : ::

true, yes, on, 1

Strings that represent ``False`` are : ::

false, no, off, 0

.. note::

        In ConfigObj 4.1.0, this method was called ``istrue``. That method is
        now deprecated and will issue a warning when used. It will go away
        in a future release.
  • **as_int**

``as_int(key)``

This returns the value contained in the specified key as an integer.

It raises a ``ValueError`` if the conversion can't be done.

  • **as_float**

``as_float(key)``

This returns the value contained in the specified key as a float.

It raises a ``ValueError`` if the conversion can't be done.

Walking a Section


.. note::

The walk method allows you to call a function on every member/name.

.. raw:: html

{+coloring}

        walk(function, raise_errors=True,
            call_on_sections=False, **keywargs):

{-coloring}

``walk`` is a method of the ``Section`` object. This means it is also a method of ConfigObj.

It walks through every member and calls a function on the keyword and value. It walks recursively through subsections.

It returns a dictionary of all the computed values.

If the function raises an exception, the default is to propagate the error, and stop. If ``raise_errors=False`` then it sets the return value for that keyword to ``False`` instead, and continues. This is similar to the way validation_ works.

Your function receives the arguments ``(section, key)``. The current value is then ``section[key]`` [#]_. Any unrecognised keyword arguments you pass to walk, are passed on to the function.

Normally ``walk`` just recurses into subsections. If you are transforming (or checking) names as well as values, then you want to be able to change the names of sections. In this case set ``call_on_sections`` to ``True``. Now, on encountering a sub-section, first the function is called for the whole sub-section, and then it recurses into it's members. This means your function must be able to handle receiving dictionaries as well as strings and lists.

If you are using the return value from ``walk`` and ``call_on_sections``, note that walk discards the return value when it calls your function.

.. caution::

You can use ``walk`` to transform the names of members of a section but you mustn't add or delete members.

Examples

Examples that use the walk method are the ``encode`` and ``decode`` methods. They both define a function and pass it to walk. Because these functions transform names as well as values (from byte strings to Unicode) they set ``call_on_sections=True``.

To see how they do it, read the source Luke {sm;:cool:}.

You can use this for transforming all values in your ConfigObj. For example you might like the nested lists from ConfigObj 3. This was provided by the listquote_ module. You could switch off the parsing for list values (``list_values=False``) and use listquote to parse every value.

Another thing you might want to do is use the Python escape codes in your values. You might be used to using ``\n`` for line feed and ``\t`` for tab. Obviously we'd need to decode strings that come from the config file (using the escape codes). Before writing out we'll need to put the escape codes back in encode.

As an example we'll write a function to use with walk, that encodes or decodes values using the ``string-escape`` codec.

The function has to take each value and set the new value. As a bonus we'll create one function that will do decode or encode depending on a keyword argument.

We don't want to work with section names, we're only transforming values, so we can leave ``call_on_sections`` as ``False``. This means the two datatypes we have to handle are strings and lists, we can ignore everything else. (We'll treat tuples as lists as well).

We're not using the return values, so it doesn't need to return anything, just change the values if appropriate.

.. raw:: html

{+coloring}

def string_escape(section, key, encode=False):

        """
        A function to encode or decode using the 'string-escape' codec.
        To be passed to the walk method of a ConfigObj.
        By default it decodes.
        To encode, pass in the keyword argument ``encode=True``.
        """
        val = section[key]
        # is it a type we can work with
        # NOTE: for platforms where Python > 2.2
        # you can use basestring instead of (str, unicode)
        if not isinstance(val, (str, unicode, list, tuple)):
            # no !
            return
        elif isinstance(val, (str, unicode)):
            # it's a string !
            if not encode:
                section[key] = val.decode('string-escape')
            else:
                section[key] = val.encode('string-escape')
        else:
            # it must be a list or tuple!
            # we'll be lazy and create a new list
            newval = []
            # we'll check every member of the list
            for entry in val:
                if isinstance(entry, (str, unicode)):
                    if not encode:
                        newval.append(entry.decode('string-escape'))
                    else:
                       newval.append(entry.encode('string-escape'))
                else:
                    newval.append(entry)
            # done !
            section[key] =  newval

# assume we have a ConfigObj called ``config`` #
# To decode
config.walk(string_escape)
#
# To encode.
# Because ``walk`` doesn't recognise the ``encode`` argument # it passes it to our function.
config.walk(string_escape, encode=True)

{-coloring}

Here's a simple example of using ``walk`` to transform names and values. One usecase of this would be to create a standard config file with placeholders for section and keynames. You can then use walk to create new config files and change values and member names :

.. raw:: html

{+coloring}

# We use 'XXXX' as a placeholder
config = '''
XXXXkey1 = XXXXvalue1
XXXXkey2 = XXXXvalue2
XXXXkey3 = XXXXvalue3
[XXXXsection1]
XXXXkey1 = XXXXvalue1
XXXXkey2 = XXXXvalue2
XXXXkey3 = XXXXvalue3
[XXXXsection2]
XXXXkey1 = XXXXvalue1
XXXXkey2 = XXXXvalue2
XXXXkey3 = XXXXvalue3

        [[XXXXsection1]]
        XXXXkey1 = XXXXvalue1
        XXXXkey2 = XXXXvalue2
        XXXXkey3 = XXXXvalue3

'''.splitlines()
cfg = ConfigObj(config)
#
def transform(section, key):

        val = section[key]
        newkey = key.replace('XXXX', 'CLIENT1')
        section.rename(key, newkey)
        if isinstance(val, (tuple, list, dict)):
            pass
        else:
            val = val.replace('XXXX', 'CLIENT1')
            section[newkey] = val

#
cfg.walk(transform, call_on_sections=True) print cfg
ConfigObj({'CLIENT1key1': 'CLIENT1value1', 'CLIENT1key2': 'CLIENT1value2', 'CLIENT1key3': 'CLIENT1value3',
'CLIENT1section1': {'CLIENT1key1': 'CLIENT1value1',

'CLIENT1key2': 'CLIENT1value2', 'CLIENT1key3': 'CLIENT1value3'}, 'CLIENT1section2': {'CLIENT1key1': 'CLIENT1value1',

        'CLIENT1key2': 'CLIENT1value2', 'CLIENT1key3': 'CLIENT1value3', 
        'CLIENT1section1': {'CLIENT1key1': 'CLIENT1value1', 
            'CLIENT1key2': 'CLIENT1value2', 'CLIENT1key3': 'CLIENT1value3'}}})

{-coloring}

Exceptions

There are several places where ConfigObj may raise exceptions (other than because of bugs).

  1. If a configspec filename you pass in doesn't exist, or a config file filename doesn't exist and ``file_error=True``, an ``IOError`` will be raised.
  2. If you try to set a non-string key, or a non string value when ``stringify=False``, a ``TypeError`` will be raised.
  3. A badly built config file will cause parsing errors.
  4. A parsing error can also occur when reading a configspec.
  5. In string interpolation you can specify a value that doesn't exist, or create circular references (recursion).
  6. If you have a ``__many__`` repeated section with other section definitions (in a configspec), a ``RepeatSectionError`` will be raised.

Number 5 (which is actually two different types of exceptions) is documented

in interpolation_.

Number 6 is explained in the validation_ section.

This section is about errors raised during parsing.

The base error class is ``ConfigObjError``. This is a subclass of ``SyntaxError``, so you can trap for ``SyntaxError`` without needing to directly import any of the ConfigObj exceptions.

The following other exceptions are defined (all deriving from ``ConfigObjError``) :

  • ``NestingError``

This error indicates either a mismatch in the brackets in a section marker, or an excessive level of nesting.

  • ``ParseError``

This error indicates that a line is badly written. It is neither a valid ``key = value`` line, nor a valid section marker line, nor a comment line.

  • ``DuplicateError``

The keyword or section specified already exists.

  • ``ConfigspecError``

An error occurred whilst parsing a configspec.

  • ``UnreprError``

An error occurred when parsing a value in `unrepr mode`_.

When parsing a configspec, ConfigObj will stop on the first error it encounters. It will raise a ``ConfigspecError``. This will have an ``error`` attribute, which is the actual error that was raised.

Behaviour when parsing a config file depends on the option ``raise_errors``. If ConfigObj encounters an error while parsing a config file:

If ``raise_errors=True`` then ConfigObj will raise the appropriate error and parsing will stop.

If ``raise_errors=False`` (the default) then parsing will continue to the end and all errors will be collected.

If ``raise_errors`` is False and multiple errors are found a ``ConfigObjError`` is raised. The error raised has a ``config`` attribute, which is the parts of the ConfigObj that parsed successfully. It also has an attribute ``errors``, which is a list of all the errors raised. Each entry in the list is an instance of the appropriate error type. Each one has the following attributes (useful for delivering a sensible error message to your user) :

  • ``line``: the original line that caused the error.
  • ``line_number``: its number in the config file.
  • ``message``: the error message that accompanied the error.

If only one error is found, then that error is re-raised. The error still has the ``config`` and ``errors`` attributes. This means that your error handling code can be the same whether one error is raised in parsing , or several.

It also means that in the most common case (a single error) a useful error message will be raised.

.. note::

One wrongly written line could break the basic structure of your config file. This could cause every line after it to flag an error, so having a list of all the lines that caused errors may not be as useful as it sounds. {sm;:-(}.

Validation

.. hint::

The system of configspecs can seem confusing at first, but is actually quite simple and powerful. For a concrete example of how to use it, you may find this blog entry helpful :
`Transforming Values with ConfigObj <http://www.voidspace.org.uk/python/weblog/arch_d7_2006_03_04.shtml#e257>`_.

There is also a module to assist in auto-generating configspecs called ConfigPersist.py_. Its use is explained in `ConfigObj for Data Persistence`_.

Validation is done through a combination of the configspec_ and a ``Validator`` object. For this you need validate.py [#]_. See downloading_ if you don't have a copy.

Validation can perform two different operations :

  1. Check that a value meets a specification. For example, check that a value is an integer between one and six, or is a choice from a specific set of options.
  2. It can convert the value into the type required. For example, if one of your values is a port number, validation will turn it into an integer for you.

So validation can act as a transparent layer between the datatypes of your application configuration (boolean, integers, floats, etc) and the text format of your config file.

configspec

The ``validate`` method checks members against an entry in the configspec. Your configspec therefore resembles your config file, with a check for every member.

In order to perform validation you need a ``Validator`` object. This has several useful built-in check functions. You can also create your own custom functions and register them with your Validator object.

Each check is the name of one of these functions, including any parameters and keyword arguments. The configspecs look like function calls, and they map to function calls.

The basic datatypes that an un-extended Validator can test for are :

  • boolean values (True and False)
  • integers (including minimum and maximum values)
  • floats (including min and max)
  • strings (including min and max length)
  • IP addresses (v4 only)

It can also handle lists of these types and restrict a value to being one from a set of options.

An example configspec is going to look something like : ::

port = integer(0, 100)
user = string(max=25)
mode = option('quiet', 'loud', 'silent')

You can specify default values, and also have the same configspec applied to several sections. This is called `repeated sections`_.

For full details on writing configspecs, please refer to the `validate.py documentation`_.

.. important::

Your configspec is read by ConfigObj in the same way as a config file.

That means you can do interpolation within your configspec.

In order to allow this, checks in the 'DEFAULT' section (of the root level of your configspec) are not used.

If you need to specify the encoding of your configspec, then you can pass in a ConfigObj instance as your configspec. When you read your configspec file, you must specify ``list_values=False``.

.. raw:: html

{+coloring}
from configobj import ConfigObj
configspec = ConfigObj(configspecfilename, encoding='UTF8',

list_values=False)
config = ConfigObj(filename, configspec=configspec) {-coloring}

.. _validate.py documentation: http://www.voidspace.org.uk/python/validate.html

Type Conversion

By default, validation does type conversion. This means that if you specify ``integer`` as the check, then calling validate_ will actually change the value to an integer (so long as the check succeeds).

It also means that when you call the write_ method, the value will be converted back into a string using the ``str`` function.

To switch this off, and leave values as strings after validation, you need to set the stringify_ attribute to ``False``. If this is the case, attempting to set a value to a non-string will raise an error.

Default Values

You can set a default value in your check. If the value is missing from the config file then this value will be used instead. This means that your user only has to supply values that differ from the defaults.

If you don't supply a default then for a value to be missing is an error, and this will show in the `return value`_ from validate.

Additionally you can set the default to be ``None``. This means the value will be set to ``None`` (the object) whichever check is used. (It will be set to ``''`` rather than ``None`` if stringify_ is ``False``). You can use this to easily implement optional values in your config files. ::

port = integer(0, 100, default=80)
user = string(max=25, default=0)
mode = option('quiet', 'loud', 'silent', default='loud') nick = string(default=None)

.. note::

Because the default goes through type conversion, it also has to pass the check.

Note that ``default=None`` is case sensitive.

List Values

It's possible that you will want to specify a list as a default value. To avoid confusing syntax with commas and quotes you use a list constructor to specify that keyword arguments are lists. This includes the ``default`` value. This makes checks look something like : ::

checkname(default=list('val1', 'val2', 'val3'))

This works with all keyword arguments, but is most useful for default values.

Repeated Sections

Repeated sections are a way of specifying a configspec for a section that should be applied to all subsections in the same section.

The easiest way of explaining this is to give an example. Suppose you have a config file that describes a dog. That dog has various attributes, but it can also have many fleas. You don't know in advance how many fleas there will be, or what they will be called, but you want each flea validated against the same configspec.

We can define a section called fleas. We want every flea in that section (every sub-section) to have the same configspec applied to it. We do this by defining a single section called ``__many__``. ::

[dog]
name = string(default=Rover)
age = float(0, 99, default=0)

[[fleas]]

            [[[__many__]]]
            bloodsucker = boolean(default=True)
            children = integer(default=10000)
            size = option(small, tiny, micro, default=tiny)

Every flea on our dog will now be validated using the ``__many__`` configspec.

If you define another sub-section in a section as well as a ``__many__`` then you will get an error.

``__many__`` sections can have sub-sections, including their own ``__many__`` sub-sections. Defaults work in the normal way in repeated sections.

Copy Mode

Because you can specify default values in your configspec, you can use ConfigObj to write out default config files for your application.

However, normally values supplied from a default in a configspec are not written out by the ``write`` method.

To do this, you need to specify ``copy=True`` when you call validate. As well as not marking values as default, all the comments in the configspec file will be copied into your ConfigObj instance.

.. raw:: html

{+coloring}
from configobj import ConfigObj
from validate import Validator
vdt = Validator()
config = ConfigObj(configspec='default.ini') config.filename = 'new_default.ini' config.validate(vdt, copy=True)
config.write()
{-coloring}

Validation and Interpolation

String interpolation and validation don't play well together. When validation changes type it sets the value. If the value uses interpolation, then the interpolation reference would normally be overwritten. Calling ``write`` would then use the absolute value and the interpolation reference would be lost.

As a compromise - if the value is unchanged by validation then it is not reset. This means strings that pass through validation unmodified will not be overwritten. If validation changes type - the value has to be overwritten, and any interpolation references are lost {sm;:-(}.

SimpleVal

You may not need a full validation process, but still want to check if all the expected values are present.

Provided as part of the ConfigObj module is the ``SimpleVal`` object. This has a dummy ``test`` method that always passes.

The only reason a test will fail is if the value is missing. The return value from ``validate`` will either be ``True``, meaning all present, or a dictionary with ``False`` for all missing values/sections.

To use it, you still need to pass in a valid configspec when you create the ConfigObj, but just set all the values to ``''``. Then create an instance of ``SimpleVal`` and pass it to the ``validate`` method.

As a trivial example if you had the following config file : ::

# config file for an application
port = 80
protocol = http
domain = voidspace
top_level_domain = org.uk

You would write the following configspec : ::

port = ''
protocol = ''
domain = ''
top_level_domain = ''

.. raw:: html

{+coloring}

config = Configobj(filename, configspec=configspec) val = SimpleVal()
test = config.validate(val)
if test == True:

print 'All values present.'
elif test == False:

print 'No values present!'

else
for entry in test:

if test[entry] == False:

print '"%s" missing.' % entry

{-coloring}

Empty values

Many config files from other applications allow empty values. As of version 4.3.0, ConfigObj will read these as an empty string.

A new option/attribute has been added (``write_empty_values``) to allow ConfigObj to write empty strings as empty values.

.. raw:: html

{+coloring}
from configobj import ConfigObj
cfg = '''

        key =
        key2 = # a comment

'''.splitlines()
config = ConfigObj(cfg)
print config
ConfigObj({'key': '', 'key2': ''})

config.write_empty_values = True
for line in config.write():

print line

key =
key2 = # a comment
{-coloring}

unrepr mode

The ``unrepr`` option allows you to store and retrieve the basic Python data-types using config files. It has to use a slightly different syntax to normal ConfigObj files. Unsurprisingly it uses Python syntax.

This means that lists are different (they are surrounded by square brackets), and strings must be quoted.

The types that ``unrepr`` can work with are :

| strings, lists tuples
| None, True, False
| dictionaries, integers, floats
| longs and complex numbers

You can't store classes, types or instances.

``unrepr`` uses ``repr(object)`` to write out values, so it currently doesn't check that you are writing valid objects. If you attempt to read an unsupported value, ConfigObj will raise a ``configobj.UnknownType`` exception.

Values that are triple quoted cased. The triple quotes are removed before converting. This means that you can use triple quotes to write dictionaries over several lines in your config files. They won't be written like this though.

If you are writing config files by hand, for use with ``unrepr``, you should be aware of the following differences from normal ConfigObj syntax :

| List : ``['A List', 'With', 'Strings']`` | Strings : ``"Must be quoted."``
| Backslash : ``"The backslash must be escaped \\"``

These all follow normal Python syntax.

In unrepr mode inline comments are not saved. This is because lines are parsed using the `compiler package <http://docs.python.org/lib/compiler.html>`_ which discards comments.

Interpolation

ConfigObj allows string interpolation similar to the way ``ConfigParser``

You specify a value to be substituted by including ``%(name)s`` in the value.

Interpolation checks first the 'DEFAULT' sub-section of the current section to see if ``name`` is the key to a value. ('name' is case sensitive).

If it doesn't find it, next it checks the 'DEFAULT' section of the parent section, last it checks the 'DEFAULT' section of the main section.

If the value specified isn't found then a ``MissingInterpolationOption`` error is raised (a subclass of ``ConfigObjError``).

If it is found then the returned value is also checked for substitutions. This allows you to make up compound values (for example directory paths) that use more than one default value. It also means it's possible to create circular references. If after ten replacements there are still values to substitute, an ``InterpolationDepthError`` is raised.

Both of these errors are subclasses of ``InterpolationError``, which is a subclass of ``ConfigObjError``.

String interpolation and validation don't play well together. This is because validation overwrites values - and so may erase the interpolation references. See `Validation and Interpolation`_. (This can only happen if validation has to change the value).

Comments

Any line that starts with a '#', possibly preceded by whitespace, is a comment.

If a config file starts with comments then these are preserved as the initial_comment_.

If a config file ends with comments then these are preserved as the final_comment_.

Every key or section marker may have lines of comments immediately above it. These are saved as the ``comments`` attribute of the section. Each member is a list of lines.

You can also have a comment inline with a value. These are saved as the ``inline_comments`` attribute of the section, with one entry per member of the section.

Subsections (section markers in the config file) can also have comments.

See `Section Attributes`_ for more on these attributes.

These comments are all written back out by the ``write`` method.

flatten_errors

::

flatten_errors(cfg, res)

Validation_ is a powerful way of checking that the values supplied by the user make sense.

The validate_ method returns a results dictionary that represents pass or fail for each value. This doesn't give you any information about why the check failed.

``flatten_errors`` is an example function that turns a results dictionary into a flat list, that only contains values that failed.

``cfg`` is the ConfigObj instance being checked, ``res`` is the results dictionary returned by ``validate``.

It returns a list of keys that failed. Each member of the list is a tuple : ::

([list of sections...], key, result)

If ``validate`` was called with ``preserve_errors=False`` (the default) then ``result`` will always be ``False``.

list of sections is a flattened list of sections that the key was found in.

If the section was missing then key will be ``None``.

If the value (or section) was missing then ``result`` will be ``False``.

If ``validate`` was called with ``preserve_errors=True`` and a value was present, but failed the check, then ``result`` will be the exception object returned. You can use this as a string that describes the failure.

For example :

The value "3" is of the wrong type.

Example Usage

The output from ``flatten_errors`` is a list of tuples.

Here is an example of how you could present this information to the user.

.. raw:: html

{+coloring}

vtor = validate.Validator()
# ini is your config file - cs is the configspec cfg = ConfigObj(ini, configspec=cs) res = cfg.validate(vtor, preserve_errors=True) for entry in flatten_errors(cfg, res):

        # each entry is a tuple
        section_list, key, error = entry
        if key is not None:
           section_list.append(key)
        else:
            section_list.append('[missing section]')
        section_string = ', '.join(section_list)
        if error == False:
            error = 'Missing value or section.'
        print section_string, ' = ', error

{-coloring}

Backwards Compatibility

There have been a lot of changes since ConfigObj 3. The core parser is now based on regular expressions, and is a lot faster and smaller. There is now no difference in the way we treat flat files and non-flatfiles, that is, no empty sections. This means some of the code can be a lot simpler, less code does more of the work [#]_.

There have been other simplifications: for example we only have eight options instead of seventeen.

Most config files created for ConfigObj 3 will be read with no changes and many programs will work without having to alter code. Some of the changes do break backwards compatibility: for example, code that uses the previous options will now raise an error. It should be very easy to fix these, though.

Below is a list of all the changes that affect backwards compatibility. This doesn't include details of method signatures that have changed, because almost all of them have.

Incompatible Changes

(I have removed a lot of needless complications: this list is probably not conclusive, many option/attribute/method names have changed.)

Case sensitive.

The only valid divider is '='.

Line continuations with ``\`` removed.

No recursive lists in values.

No empty sections.

No distinction between flatfiles and non flatfiles.

Change in list syntax: use commas to indicate list, not parentheses (square brackets and parentheses are no longer recognised as lists).

';' is no longer valid for comments, and no multiline comments.

No attribute-style access to values.

Empty values not allowed: use '' or "".

In ConfigObj 3, setting a non-flatfile member to ``None`` would initialise it as an empty section.

The escape entities '&mjf-lf;' and '&mjf-quot;' have gone, replaced by triple quote, multiple line values.

The ``newline``, ``force_return``, and ``default`` options have gone.

``fileerror`` and ``createempty`` options have become ``file_error`` and ``create_empty``.

Partial configspecs (for specifying the order members should be written out, and which should be present) have gone. The configspec is no longer used to specify order for the ``write`` method.

Exceeding the maximum depth of recursion in string interpolation now raises an error ``InterpolationDepthError``.

Specifying a value for interpolation which doesn't exist now raises a ``MissingInterpolationOption`` error (instead of merely being ignored).

The ``writein`` method has been removed.

The comments attribute is now a list (``inline_comments`` equates to the old comments attribute).

ConfigObj 3

ConfigObj 3 is now deprecated in favour of ConfigObj 4. I can fix bugs in ConfigObj 3 if needed, though.

For anyone who still needs it, you can download it here: `ConfigObj 3.3.1`_

You can read the old docs at : `ConfigObj 3 Docs`_

.. _ConfigObj 3.3.1: http://www.voidspace.org.uk/cgi-bin/voidspace/downman.py?file=configobj3.zip .. _ConfigObj 3 Docs: http://www.voidspace.org.uk/python/configobj3.html

CREDITS

ConfigObj 4 is written by (and copyright) `Michael Foord`_ and `Nicola Larosa`_.

Particularly thanks to Nicola Larosa for help on the config file spec, the validation system and the doctests.

validate.py was originally written by Michael Foord and `Mark Andrews`_.

Thanks to others for input and bugfixes.

LICENSE

ConfigObj, and related files, are licensed under the BSD license. This is a very unrestrictive license, but it comes with the usual disclaimer. This is free software: test it, break it, just don't blame us if it eats your data ! Of course if it does, let us know and we'll fix the problem so it doesn't happen to anyone else {sm;:-)}. ::

Copyright (c) 2004 - 2006, Michael Foord & Nicola Larosa All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are

met
  • Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
  • Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
  • Neither the name of Michael Foord nor Nicola Larosa may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

You should also be able to find a copy of this license at : `BSD License`_

.. _BSD License: http://www.voidspace.org.uk/python/license.shtml

TODO

Better support for configuration from multiple files, including tracking where the original file came from and writing changes to the correct file.

Make ``newline`` an option (as well as an attribute) ?

``UTF16`` encoded files, when returned as a list of lines, will have the BOM at the start of every line. Should this be removed from all but the first line ?

Option to set warning type for unicode decode ? (Defaults to strict).

A method to optionally remove uniform indentation from multiline values. (do as an example of using ``walk`` - along with string-escape)

Should the results dictionary from validate be an ordered dictionary if `odict <http://www.voidspace.org.uk/python/odict.html>`_ is available ?

Implement some of the sequence methods (which include slicing) from the newer ``odict`` ?

Preserve line numbers of values (and possibly the original text of each value).

ISSUES

.. note::

Please file any bug reports to `Michael Foord`_ or the **ConfigObj** `Mailing List`_.

There is currently no way to specify the encoding of a configspec file.

When using ``copy`` mode for validation, it won't copy ``DEFAULT`` sections. This is so that you can use interpolation in configspec files.

``validate`` doesn't report extra values or sections.

You can't have a keyword with the same name as a section (in the same section). They are both dictionary keys - so they would overlap.

ConfigObj doesn't quote and unquote values if ``list_values=False``. This means that leading or trailing whitespace in values will be lost when writing. (Unless you manually quote).

Interpolation checks first the 'DEFAULT' subsection of the current section, next it checks the 'DEFAULT' section of the parent section, last it checks the 'DEFAULT' section of the main section.

Logically a 'DEFAULT' section should apply to all subsections of the same parent - this means that checking the 'DEFAULT' subsection in the current section is not necessarily logical ?

Does it matter that we don't support the ':' divider, which is supported by ``ConfigParser`` ?

String interpolation and validation don't play well together. When validation changes type it sets the value. This will correctly fetch the value using interpolation - but then overwrite the interpolation reference. If the value is unchanged by validation (it's a string) - but other types will be.

CHANGELOG

This is an abbreviated changelog showing the major releases up to version 4. From version 4 it lists all releases and changes. More data on individual changes may be found in the source code or the CHANGELOG file.

2006/06/04 - Version 4.3.2

Changed error handling, if parsing finds a single error then that error will be re-raised. That error will still have an ``errors`` and a ``config`` attribute.

Fixed bug where '\n' terminated files could be truncated.

Bugfix in ``unrepr`` mode, it couldn't handle '#' in values. (Thanks to Philippe Normand for the report.)

As a consequence of this fix, ConfigObj doesn't now keep inline comments in ``unrepr`` mode. This is because the parser in the `compiler package`_ doesn't keep comments. {sm;:-)}

Error messages are now more useful. They tell you the number of parsing errors and the line number of the first error. (In the case of multiple errors.)

Line numbers in exceptions now start at 1, not 0.

Errors in ``unrepr`` mode are now handled the same way as in the normal mode. The errors stored will be an ``UnreprError``.

2006/04/29 - Version 4.3.1

Added ``validate.py`` back into ``configobj.zip``. (Thanks to Stewart Midwinter)

Updated to `validate.py`_ 0.2.2.

Preserve tuples when calling the ``dict`` method. (Thanks to Gustavo Niemeyer.)

Changed ``__repr__`` to return a string that contains ``ConfigObj({ ... })``.

Change so that an options dictionary isn't modified by passing it to ConfigObj. (Thanks to Artarious.)

Added ability to handle negative integers in ``unrepr``. (Thanks to Kevin Dangoor.)

2006/03/24 - Version 4.3.0

Moved the tests and the CHANGELOG (etc) into a separate file. This has reduced the size of ``configobj.py`` by about 40%.

Added the ``unrepr`` mode to reading and writing config files. Thanks to Kevin Dangoor for this suggestion.

Empty values are now valid syntax. They are read as an empty string ``''``. (``key =``, or ``key = # comment``.)

``validate`` now honours the order of the configspec.

Added the ``copy`` mode to validate. Thanks to Louis Cordier for this suggestion.

Fixed bug where files written on windows could be given ``'\r\r\n'`` line terminators.

Fixed bug where last occurring comment line could be interpreted as the final comment if the last line isn't terminated.

Fixed bug where nested list values would be flattened when ``write`` is called. Now sub-lists have a string representation written instead.

Deprecated ``encode`` and ``decode`` methods instead.

You can now pass in a ConfigObj instance as a configspec (remember to read the configspec file using ``list_values=False``).

Sorted footnotes in the docs.

2006/02/16 - Version 4.2.0

Removed ``BOM_UTF8`` from ``__all__``.

The ``BOM`` attribute has become a boolean. (Defaults to ``False``.) It is only ``True`` for the ``UTF16/UTF8`` encodings.

File like objects no longer need a ``seek`` attribute.

Full unicode support added. New options/attributes ``encoding``, ``default_encoding``.

ConfigObj no longer keeps a reference to file like objects. Instead the ``write`` method takes a file like object as an optional argument. (Which will be used in preference of the ``filename`` attribute if that exists as well.)

utf16 files decoded to unicode.

If ``BOM`` is ``True``, but no encoding specified, then the utf8 BOM is written out at the start of the file. (It will normally only be ``True`` if the utf8 BOM was found when the file was read.)

Thanks to Aaron Bentley for help and testing on the unicode issues.

File paths are not converted to absolute paths, relative paths will remain relative as the ``filename`` attribute.

Fixed bug where ``final_comment`` wasn't returned if ``write`` is returning a list of lines.

Deprecated ``istrue``, replaced it with ``as_bool``.

Added ``as_int`` and ``as_float``.

2005/12/14 - Version 4.1.0

Added ``merge``, a recursive update.

Added ``preserve_errors`` to ``validate`` and the ``flatten_errors`` example function.

Thanks to Matthew Brett for suggestions and helping me iron out bugs.

Fixed bug where a config file is all comment, the comment will now be ``initial_comment`` rather than ``final_comment``.

Validation no longer done on the 'DEFAULT' section (only in the root level). This allows interpolation in configspecs.

Also use the new list syntax in validate_ 0.2.1. (For configspecs).

2005/12/02 - Version 4.0.2

Fixed bug in ``create_empty``. Thanks to Paul Jimenez for the report.

2005/11/05 - Version 4.0.1

Fixed bug in ``Section.walk`` when transforming names as well as values.

Added the ``istrue`` method. (Fetches the boolean equivalent of a string value).

Fixed ``list_values=False`` - they are now only quoted/unquoted if they are multiline values.

List values are written as ``item, item`` rather than ``item,item``.

2005/10/17 - Version 4.0.0

**ConfigObj 4.0.0 Final**

Fixed bug in ``setdefault``. When creating a new section with setdefault the reference returned would be to the dictionary passed in not to the new section. Bug fixed and behaviour documented.

Obscure typo/bug fixed in ``write``. Wouldn't have affected anyone though.

2005/09/09 - Version 4.0.0 beta 5

Removed ``PositionError``.

Allowed quotes around keys as documented.

Fixed bug with commas in comments. (matched as a list value)

2005/09/07 - Version 4.0.0 beta 4

Fixed bug in ``__delitem__``. Deleting an item no longer deletes the ``inline_comments`` attribute.

Fixed bug in initialising ConfigObj from a ConfigObj.

Changed the mailing list address.

2005/08/28 - Version 4.0.0 beta 3

Interpolation is switched off before writing out files.

Fixed bug in handling ``StringIO`` instances. (Thanks to report from "Gustavo Niemeyer" <gustavo@niemeyer.net>)

Moved the doctests from the ``__init__`` method to a separate function. (For the sake of IDE calltips).

2005/08/25 - Version 4.0.0 beta 2

Amendments to validate.py.

Official release.

2005/08/21 - Version 4.0.0 beta 1

Reads nested subsections to any depth.

Multiline values.

Simplified options and methods.

New list syntax.

Faster, smaller, and better parser.

Validation greatly improved. Includes:

  • type conversion
  • default values
  • repeated sections

Improved error handling.

Plus lots of other improvements {sm;:grin:}.

2004/05/24 - Version 3.0.0

Several incompatible changes: another major overhaul and change. (Lots of improvements though).

Added support for standard config files with sections. This has an entirely new interface: each section is a dictionary of values.

Changed the update method to be called writein: update clashes with a dict method.

Made various attributes keyword arguments, added several.

Configspecs and orderlists have changed a great deal.

Removed support for adding dictionaries: use update instead.

Now subclasses a new class called caselessDict. This should add various dictionary methods that could have caused errors before.

It also preserves the original casing of keywords when writing them back out.

Comments are also saved using a ``caselessDict``.

Using a non-string key will now raise a ``TypeError`` rather than converting the key.

Added an exceptions keyword for much better handling of errors.

Made ``creatempty=False`` the default.

Now checks indict and any keyword args. Keyword args take precedence over indict.

``' ', ':', '=', ','`` and ``'\t'`` are now all valid dividers where the keyword is unquoted.

ConfigObj now does no type checking against configspec when you set items.

delete and add methods removed (they were unnecessary).

Docs rewritten to include all this gumph and more; actually ConfigObj is really easy to use.

Support for stdout was removed.

A few new methods added.

Charmap is now incorporated into ConfigObj.

2004/03/14 - Version 2.0.0 beta

Re-written it to subclass dict. My first forays into inheritance and operator overloading.

The config object now behaves like a dictionary.

I've completely broken the interface, but I don't think anyone was really using it anyway.

This new version is much more 'classy' {sm;:wink:}

It will also read straight from/to a filename and completely parse a config file without you having to supply a config spec.

Uses listparse, so can handle nested list items as values.

No longer has getval and setval methods: use normal dictionary methods, or add and delete.

2004/01/29 - Version 1.0.5

Version 1.0.5 has a couple of bugfixes as well as a couple of useful additions over previous versions.

Since 1.0.0 the buildconfig function has been moved into this distribution, and the methods reset, verify, getval and setval have been added.

A couple of bugs have been fixed.

Origins

ConfigObj originated in a set of functions for reading config files in the `atlantibots <http://www.voidspace.org.uk/atlantibots/>`_ project. The original functions were written by Rob McNeur.


Footnotes

.. [#] 315 of them, at the time of writing.

.. [#] And if you discover any bugs, let us know. We'll fix them quickly.

.. [#] If you specify a filename that doesn't exist, ConfigObj will assume you

are creating a new one. See the create_empty and file_error options_.

.. [#] They can be byte strings (ordinary strings) or Unicode.

.. [#] Except we don't support the RFC822 style line continuations, nor ':' as

a divider.

.. [#] This is a change in ConfigObj 4.2.0. Note that ConfigObj doesn't call

the seek method of any file like object you pass in. You may want to call ``file_object.seek(0)`` yourself, first.

.. [#] A side effect of this is that it enables you to copy a ConfigObj :

.. raw:: html

{+coloring}

        # only copies members
        # not attributes/comments
        config2 = ConfigObj(config1)
    
        {-coloring}

The order of values and sections will not be preserved, though.

.. [#] Other than lists of strings.

.. [#] The exception is if it detects a ``UTF16`` encoded file which it

must decode before parsing.

.. [#] The method signature in the API docs will show that this method takes

two arguments. The second is the section to be written. This is because the ``write`` method is called recursively.

.. [#] The dict method doesn't actually use the deepcopy mechanism. This means

if you add nested lists (etc) to your ConfigObj, then the dictionary returned by dict may contain some references. For all normal ConfigObjs it will return a deepcopy.

.. [#] Passing ``(section, key)`` rather than ``(value, key)`` allows you to

change the value by setting ``section[key] = newval``. It also gives you access to the rename method of the section.

.. [#] Minimum required version of validate.py 0.2.0 .

.. [#] It also makes ConfigObj a lot simpler to use.

.. note::

Rendering this document with docutils also needs the textmacros module and the PySrc CSS stuff. See http://www.voidspace.org.uk/python/firedrop2/textmacros.shtml

.. raw:: html

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.. _listquote: http://www.voidspace.org.uk/python/modules.shtml#listquote .. _Michael Foord: http://www.voidspace.org.uk/index2.shtml .. _Nicola Larosa: http://www.teknico.net .. _Mark Andrews: http://www.la-la.com


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