14.2. `configparser` — Configuration file parser¶

Source code: Lib/configparser.py

This module provides the ConfigParser class which implements a basic configuration language which provides a structure similar to what’s found in Microsoft Windows INI files. You can use this to write Python programs which can be customized by end users easily.

Note

This library does not interpret or write the value-type prefixes used in the Windows Registry extended version of INI syntax.

14.2.1. Quick Start¶

Let’s take a very basic configuration file that looks like this:

[DEFAULT]
ServerAliveInterval = 45
Compression = yes
CompressionLevel = 9
ForwardX11 = yes

[bitbucket.org]
User = hg

[topsecret.server.com]
Port = 50022
ForwardX11 = no

The structure of INI files is described in the following section. Essentially, the file consists of sections, each of which contains keys with values. configparser classes can read and write such files. Let’s start by creating the above configuration file programatically.

>>> import configparser
>>> config = configparser.ConfigParser()
>>> config['DEFAULT'] = {'ServerAliveInterval': '45',
...                      'Compression': 'yes',
...                      'CompressionLevel': '9'}
>>> config['bitbucket.org'] = {}
>>> config['bitbucket.org']['User'] = 'hg'
>>> config['topsecret.server.com'] = {}
>>> topsecret = config['topsecret.server.com']
>>> topsecret['Port'] = '50022'     # mutates the parser
>>> topsecret['ForwardX11'] = 'no'  # same here
>>> config['DEFAULT']['ForwardX11'] = 'yes'
>>> with open('example.ini', 'w') as configfile:
...   config.write(configfile)
...

As you can see, we can treat a config parser much like a dictionary. There are differences, outlined later, but the behavior is very close to what you would expect from a dictionary.

Now that we have created and saved a configuration file, let’s read it back and explore the data it holds.

>>> import configparser
>>> config = configparser.ConfigParser()
>>> config.sections()
[]
>>> config.read('example.ini')
['example.ini']
>>> config.sections()
['bitbucket.org', 'topsecret.server.com']
>>> 'bitbucket.org' in config
True
>>> 'bytebong.com' in config
False
>>> config['bitbucket.org']['User']
'hg'
>>> config['DEFAULT']['Compression']
'yes'
>>> topsecret = config['topsecret.server.com']
>>> topsecret['ForwardX11']
'no'
>>> topsecret['Port']
'50022'
>>> for key in config['bitbucket.org']: print(key)
...
user
compressionlevel
serveraliveinterval
compression
forwardx11
>>> config['bitbucket.org']['ForwardX11']
'yes'

As we can see above, the API is pretty straightforward. The only bit of magic involves the DEFAULT section which provides default values for all other sections [1]. Note also that keys in sections are case-insensitive and stored in lowercase [1].

14.2.2. Supported Datatypes¶

Config parsers do not guess datatypes of values in configuration files, always storing them internally as strings. This means that if you need other datatypes, you should convert on your own:

>>> int(topsecret['Port'])
50022
>>> float(topsecret['CompressionLevel'])
9.0

Since this task is so common, config parsers provide a range of handy getter methods to handle integers, floats and booleans. The last one is the most interesting because simply passing the value to bool() would do no good since bool('False') is still True. This is why config parsers also provide getboolean(). This method is case-insensitive and recognizes Boolean values from 'yes'/'no', 'on'/'off', 'true'/'false' and '1'/'0' [1]. For example:

>>> topsecret.getboolean('ForwardX11')
False
>>> config['bitbucket.org'].getboolean('ForwardX11')
True
>>> config.getboolean('bitbucket.org', 'Compression')
True

Apart from getboolean(), config parsers also provide equivalent getint() and getfloat() methods. You can register your own converters and customize the provided ones. [1]

14.2.3. Fallback Values¶

As with a dictionary, you can use a section’s get() method to provide fallback values:

>>> topsecret.get('Port')
'50022'
>>> topsecret.get('CompressionLevel')
'9'
>>> topsecret.get('Cipher')
>>> topsecret.get('Cipher', '3des-cbc')
'3des-cbc'

Please note that default values have precedence over fallback values. For instance, in our example the 'CompressionLevel' key was specified only in the 'DEFAULT' section. If we try to get it from the section 'topsecret.server.com', we will always get the default, even if we specify a fallback:

>>> topsecret.get('CompressionLevel', '3')
'9'

One more thing to be aware of is that the parser-level get() method provides a custom, more complex interface, maintained for backwards compatibility. When using this method, a fallback value can be provided via the fallback keyword-only argument:

>>> config.get('bitbucket.org', 'monster',
...            fallback='No such things as monsters')
'No such things as monsters'

The same fallback argument can be used with the getint(), getfloat() and getboolean() methods, for example:

>>> 'BatchMode' in topsecret
False
>>> topsecret.getboolean('BatchMode', fallback=True)
True
>>> config['DEFAULT']['BatchMode'] = 'no'
>>> topsecret.getboolean('BatchMode', fallback=True)
False

14.2.4. Supported INI File Structure¶

A configuration file consists of sections, each led by a [section] header, followed by key/value entries separated by a specific string (= or : by default [1]). By default, section names are case sensitive but keys are not [1]. Leading and trailing whitespace is removed from keys and values. Values can be omitted, in which case the key/value delimiter may also be left out. Values can also span multiple lines, as long as they are indented deeper than the first line of the value. Depending on the parser’s mode, blank lines may be treated as parts of multiline values or ignored.

Configuration files may include comments, prefixed by specific characters (# and ; by default [1]). Comments may appear on their own on an otherwise empty line, possibly indented. [1]

For example:

[Simple Values]
key=value
spaces in keys=allowed
spaces in values=allowed as well
spaces around the delimiter = obviously
you can also use : to delimit keys from values

[All Values Are Strings]
values like this: 1000000
or this: 3.14159265359
are they treated as numbers? : no
integers, floats and booleans are held as: strings
can use the API to get converted values directly: true

[Multiline Values]
chorus: I'm a lumberjack, and I'm okay
    I sleep all night and I work all day

[No Values]
key_without_value
empty string value here =

[You can use comments]
# like this
; or this

# By default only in an empty line.
# Inline comments can be harmful because they prevent users
# from using the delimiting characters as parts of values.
# That being said, this can be customized.

    [Sections Can Be Indented]
        can_values_be_as_well = True
        does_that_mean_anything_special = False
        purpose = formatting for readability
        multiline_values = are
            handled just fine as
            long as they are indented
            deeper than the first line
            of a value
        # Did I mention we can indent comments, too?

14.2.5. Interpolation of values¶

On top of the core functionality, ConfigParser supports interpolation. This means values can be preprocessed before returning them from get() calls.

class configparser.BasicInterpolation¶

The default implementation used by ConfigParser. It enables values to contain format strings which refer to other values in the same section, or values in the special default section [1]. Additional default values can be provided on initialization.

For example:

[Paths]
home_dir: /Users
my_dir: %(home_dir)s/lumberjack
my_pictures: %(my_dir)s/Pictures

In the example above, ConfigParser with interpolation set to BasicInterpolation() would resolve %(home_dir)s to the value of home_dir (/Users in this case). %(my_dir)s in effect would resolve to /Users/lumberjack. All interpolations are done on demand so keys used in the chain of references do not have to be specified in any specific order in the configuration file.

With interpolation set to None, the parser would simply return %(my_dir)s/Pictures as the value of my_pictures and %(home_dir)s/lumberjack as the value of my_dir.

class configparser.ExtendedInterpolation¶

An alternative handler for interpolation which implements a more advanced syntax, used for instance in zc.buildout. Extended interpolation is using ${section:option} to denote a value from a foreign section. Interpolation can span multiple levels. For convenience, if the section: part is omitted, interpolation defaults to the current section (and possibly the default values from the special section).

For example, the configuration specified above with basic interpolation, would look like this with extended interpolation:

[Paths]
home_dir: /Users
my_dir: ${home_dir}/lumberjack
my_pictures: ${my_dir}/Pictures

Values from other sections can be fetched as well:

[Common]
home_dir: /Users
library_dir: /Library
system_dir: /System
macports_dir: /opt/local

[Frameworks]
Python: 3.2
path: ${Common:system_dir}/Library/Frameworks/

[Arthur]
nickname: Two Sheds
last_name: Jackson
my_dir: ${Common:home_dir}/twosheds
my_pictures: ${my_dir}/Pictures
python_dir: ${Frameworks:path}/Python/Versions/${Frameworks:Python}

14.2.6. Mapping Protocol Access¶

New in version 3.2.

Mapping protocol access is a generic name for functionality that enables using custom objects as if they were dictionaries. In case of configparser, the mapping interface implementation is using the parser['section']['option'] notation.

parser['section'] in particular returns a proxy for the section’s data in the parser. This means that the values are not copied but they are taken from the original parser on demand. What’s even more important is that when values are changed on a section proxy, they are actually mutated in the original parser.

configparser objects behave as close to actual dictionaries as possible. The mapping interface is complete and adheres to the MutableMapping ABC. However, there are a few differences that should be taken into account:

By default, all keys in sections are accessible in a case-insensitive manner [1]. E.g. for option in parser["section"] yields only optionxform‘ed option key names. This means lowercased keys by default. At the same time, for a section that holds the key 'a', both expressions return True:
```
"a" in parser["section"]
"A" in parser["section"]
```
All sections include DEFAULTSECT values as well which means that .clear() on a section may not leave the section visibly empty. This is because default values cannot be deleted from the section (because technically they are not there). If they are overridden in the section, deleting causes the default value to be visible again. Trying to delete a default value causes a KeyError.
DEFAULTSECT cannot be removed from the parser:
- trying to delete it raises ValueError,
- parser.clear() leaves it intact,
- parser.popitem() never returns it.
parser.get(section, option, **kwargs) - the second argument is not a fallback value. Note however that the section-level get() methods are compatible both with the mapping protocol and the classic configparser API.
parser.items() is compatible with the mapping protocol (returns a list of section_name, section_proxy pairs including the DEFAULTSECT). However, this method can also be invoked with arguments: parser.items(section, raw, vars). The latter call returns a list of option, value pairs for a specified section, with all interpolations expanded (unless raw=True is provided).

The mapping protocol is implemented on top of the existing legacy API so that subclasses overriding the original interface still should have mappings working as expected.

14.2.7. Customizing Parser Behaviour¶

There are nearly as many INI format variants as there are applications using it. configparser goes a long way to provide support for the largest sensible set of INI styles available. The default functionality is mainly dictated by historical background and it’s very likely that you will want to customize some of the features.

The most common way to change the way a specific config parser works is to use the __init__() options:

defaults, default value: None

This option accepts a dictionary of key-value pairs which will be initially put in the DEFAULT section. This makes for an elegant way to support concise configuration files that don’t specify values which are the same as the documented default.

Hint: if you want to specify default values for a specific section, use read_dict() before you read the actual file.

dict_type, default value: collections.OrderedDict

This option has a major impact on how the mapping protocol will behave and how the written configuration files look. With the default ordered dictionary, every section is stored in the order they were added to the parser. Same goes for options within sections.

An alternative dictionary type can be used for example to sort sections and options on write-back. You can also use a regular dictionary for performance reasons.

Please note: there are ways to add a set of key-value pairs in a single operation. When you use a regular dictionary in those operations, the order of the keys may be random. For example:

>>> parser = configparser.ConfigParser()
>>> parser.read_dict({'section1': {'key1': 'value1',
...                                'key2': 'value2',
...                                'key3': 'value3'},
...                   'section2': {'keyA': 'valueA',
...                                'keyB': 'valueB',
...                                'keyC': 'valueC'},
...                   'section3': {'foo': 'x',
...                                'bar': 'y',
...                                'baz': 'z'}
... })
>>> parser.sections()
['section3', 'section2', 'section1']
>>> [option for option in parser['section3']]
['baz', 'foo', 'bar']

In these operations you need to use an ordered dictionary as well:

>>> from collections import OrderedDict
>>> parser = configparser.ConfigParser()
>>> parser.read_dict(
...   OrderedDict((
...     ('s1',
...      OrderedDict((
...        ('1', '2'),
...        ('3', '4'),
...        ('5', '6'),
...      ))
...     ),
...     ('s2',
...      OrderedDict((
...        ('a', 'b'),
...        ('c', 'd'),
...        ('e', 'f'),
...      ))
...     ),
...   ))
... )
>>> parser.sections()
['s1', 's2']
>>> [option for option in parser['s1']]
['1', '3', '5']
>>> [option for option in parser['s2'].values()]
['b', 'd', 'f']

allow_no_value, default value: False

Some configuration files are known to include settings without values, but which otherwise conform to the syntax supported by configparser. The allow_no_value parameter to the constructor can be used to indicate that such values should be accepted:

>>> import configparser

>>> sample_config = """
... [mysqld]
...   user = mysql
...   pid-file = /var/run/mysqld/mysqld.pid
...   skip-external-locking
...   old_passwords = 1
...   skip-bdb
...   # we don't need ACID today
...   skip-innodb
... """
>>> config = configparser.ConfigParser(allow_no_value=True)
>>> config.read_string(sample_config)

>>> # Settings with values are treated as before:
>>> config["mysqld"]["user"]
'mysql'

>>> # Settings without values provide None:
>>> config["mysqld"]["skip-bdb"]

>>> # Settings which aren't specified still raise an error:
>>> config["mysqld"]["does-not-exist"]
Traceback (most recent call last):
  ...
KeyError: 'does-not-exist'

delimiters, default value: ('=', ':')

Delimiters are substrings that delimit keys from values within a section. The first occurrence of a delimiting substring on a line is considered a delimiter. This means values (but not keys) can contain the delimiters.

See also the space_around_delimiters argument to ConfigParser.write().
comment_prefixes, default value: ('#', ';')

inline_comment_prefixes, default value: None

Comment prefixes are strings that indicate the start of a valid comment within a config file. comment_prefixes are used only on otherwise empty lines (optionally indented) whereas inline_comment_prefixes can be used after every valid value (e.g. section names, options and empty lines as well). By default inline comments are disabled and '#' and ';' are used as prefixes for whole line comments.

Changed in version 3.2: In previous versions of configparser behaviour matched comment_prefixes=('#',';') and inline_comment_prefixes=(';',).

Please note that config parsers don’t support escaping of comment prefixes so using inline_comment_prefixes may prevent users from specifying option values with characters used as comment prefixes. When in doubt, avoid setting inline_comment_prefixes. In any circumstances, the only way of storing comment prefix characters at the beginning of a line in multiline values is to interpolate the prefix, for example:

>>> from configparser import ConfigParser, ExtendedInterpolation
>>> parser = ConfigParser(interpolation=ExtendedInterpolation())
>>> # the default BasicInterpolation could be used as well
>>> parser.read_string("""
... [DEFAULT]
... hash = #
...
... [hashes]
... shebang =
...   ${hash}!/usr/bin/env python
...   ${hash} -*- coding: utf-8 -*-
...
... extensions =
...   enabled_extension
...   another_extension
...   #disabled_by_comment
...   yet_another_extension
...
... interpolation not necessary = if # is not at line start
... even in multiline values = line #1
...   line #2
...   line #3
... """)
>>> print(parser['hashes']['shebang'])

#!/usr/bin/env python
# -*- coding: utf-8 -*-
>>> print(parser['hashes']['extensions'])

enabled_extension
another_extension
yet_another_extension
>>> print(parser['hashes']['interpolation not necessary'])
if # is not at line start
>>> print(parser['hashes']['even in multiline values'])
line #1
line #2
line #3

strict, default value: True

When set to True, the parser will not allow for any section or option duplicates while reading from a single source (using read_file(), read_string() or read_dict()). It is recommended to use strict parsers in new applications.

Changed in version 3.2: In previous versions of configparser behaviour matched strict=False.
empty_lines_in_values, default value: True

In config parsers, values can span multiple lines as long as they are indented more than the key that holds them. By default parsers also let empty lines to be parts of values. At the same time, keys can be arbitrarily indented themselves to improve readability. In consequence, when configuration files get big and complex, it is easy for the user to lose track of the file structure. Take for instance:
```
[Section]
key = multiline
  value with a gotcha

 this = is still a part of the multiline value of 'key'
```
This can be especially problematic for the user to see if she’s using a proportional font to edit the file. That is why when your application does not need values with empty lines, you should consider disallowing them. This will make empty lines split keys every time. In the example above, it would produce two keys, key and this.
default_section, default value: configparser.DEFAULTSECT (that is: "DEFAULT")

The convention of allowing a special section of default values for other sections or interpolation purposes is a powerful concept of this library, letting users create complex declarative configurations. This section is normally called "DEFAULT" but this can be customized to point to any other valid section name. Some typical values include: "general" or "common". The name provided is used for recognizing default sections when reading from any source and is used when writing configuration back to a file. Its current value can be retrieved using the parser_instance.default_section attribute and may be modified at runtime (i.e. to convert files from one format to another).
interpolation, default value: configparser.BasicInterpolation

Interpolation behaviour may be customized by providing a custom handler through the interpolation argument. None can be used to turn off interpolation completely, ExtendedInterpolation() provides a more advanced variant inspired by zc.buildout. More on the subject in the dedicated documentation section. RawConfigParser has a default value of None.
converters, default value: not set

Config parsers provide option value getters that perform type conversion. By default getint(), getfloat(), and getboolean() are implemented. Should other getters be desirable, users may define them in a subclass or pass a dictionary where each key is a name of the converter and each value is a callable implementing said conversion. For instance, passing {'decimal': decimal.Decimal} would add getdecimal() on both the parser object and all section proxies. In other words, it will be possible to write both parser_instance.getdecimal('section', 'key', fallback=0) and parser_instance['section'].getdecimal('key', 0).

If the converter needs to access the state of the parser, it can be implemented as a method on a config parser subclass. If the name of this method starts with get, it will be available on all section proxies, in the dict-compatible form (see the getdecimal() example above).

More advanced customization may be achieved by overriding default values of these parser attributes. The defaults are defined on the classes, so they may be overridden by subclasses or by attribute assignment.

configparser.BOOLEAN_STATES¶

By default when using getboolean(), config parsers consider the following values True: '1', 'yes', 'true', 'on' and the following values False: '0', 'no', 'false', 'off'. You can override this by specifying a custom dictionary of strings and their Boolean outcomes. For example:

>>> custom = configparser.ConfigParser()
>>> custom['section1'] = {'funky': 'nope'}
>>> custom['section1'].getboolean('funky')
Traceback (most recent call last):
...
ValueError: Not a boolean: nope
>>> custom.BOOLEAN_STATES = {'sure': True, 'nope': False}
>>> custom['section1'].getboolean('funky')
False

Other typical Boolean pairs include accept/reject or enabled/disabled.

configparser.optionxform(option)¶

This method transforms option names on every read, get, or set operation. The default converts the name to lowercase. This also means that when a configuration file gets written, all keys will be lowercase. Override this method if that’s unsuitable. For example:

>>> config = """
... [Section1]
... Key = Value
...
... [Section2]
... AnotherKey = Value
... """
>>> typical = configparser.ConfigParser()
>>> typical.read_string(config)
>>> list(typical['Section1'].keys())
['key']
>>> list(typical['Section2'].keys())
['anotherkey']
>>> custom = configparser.RawConfigParser()
>>> custom.optionxform = lambda option: option
>>> custom.read_string(config)
>>> list(custom['Section1'].keys())
['Key']
>>> list(custom['Section2'].keys())
['AnotherKey']

configparser.SECTCRE¶

A compiled regular expression used to parse section headers. The default matches [section] to the name "section". Whitespace is considered part of the section name, thus [ larch ] will be read as a section of name " larch ". Override this attribute if that’s unsuitable. For example:

>>> config = """
... [Section 1]
... option = value
...
... [  Section 2  ]
... another = val
... """
>>> typical = ConfigParser()
>>> typical.read_string(config)
>>> typical.sections()
['Section 1', '  Section 2  ']
>>> custom = ConfigParser()
>>> custom.SECTCRE = re.compile(r"\[ *(?P<header>[^]]+?) *\]")
>>> custom.read_string(config)
>>> custom.sections()
['Section 1', 'Section 2']

Note

While ConfigParser objects also use an OPTCRE attribute for recognizing option lines, it’s not recommended to override it because that would interfere with constructor options allow_no_value and delimiters.

14.2.8. Legacy API Examples¶

Mainly because of backwards compatibility concerns, configparser provides also a legacy API with explicit get/set methods. While there are valid use cases for the methods outlined below, mapping protocol access is preferred for new projects. The legacy API is at times more advanced, low-level and downright counterintuitive.

An example of writing to a configuration file:

import configparser

config = configparser.RawConfigParser()

# Please note that using RawConfigParser's set functions, you can assign
# non-string values to keys internally, but will receive an error when
# attempting to write to a file or when you get it in non-raw mode. Setting
# values using the mapping protocol or ConfigParser's set() does not allow
# such assignments to take place.
config.add_section('Section1')
config.set('Section1', 'an_int', '15')
config.set('Section1', 'a_bool', 'true')
config.set('Section1', 'a_float', '3.1415')
config.set('Section1', 'baz', 'fun')
config.set('Section1', 'bar', 'Python')
config.set('Section1', 'foo', '%(bar)s is %(baz)s!')

# Writing our configuration file to 'example.cfg'
with open('example.cfg', 'w') as configfile:
    config.write(configfile)

An example of reading the configuration file again:

import configparser

config = configparser.RawConfigParser()
config.read('example.cfg')

# getfloat() raises an exception if the value is not a float
# getint() and getboolean() also do this for their respective types
a_float = config.getfloat('Section1', 'a_float')
an_int = config.getint('Section1', 'an_int')
print(a_float + an_int)

# Notice that the next output does not interpolate '%(bar)s' or '%(baz)s'.
# This is because we are using a RawConfigParser().
if config.getboolean('Section1', 'a_bool'):
    print(config.get('Section1', 'foo'))

To get interpolation, use ConfigParser:

import configparser

cfg = configparser.ConfigParser()
cfg.read('example.cfg')

# Set the optional *raw* argument of get() to True if you wish to disable
# interpolation in a single get operation.
print(cfg.get('Section1', 'foo', raw=False)) # -> "Python is fun!"
print(cfg.get('Section1', 'foo', raw=True))  # -> "%(bar)s is %(baz)s!"

# The optional *vars* argument is a dict with members that will take
# precedence in interpolation.
print(cfg.get('Section1', 'foo', vars={'bar': 'Documentation',
                                          'baz': 'evil'}))

# The optional *fallback* argument can be used to provide a fallback value
print(cfg.get('Section1', 'foo'))
      # -> "Python is fun!"

print(cfg.get('Section1', 'foo', fallback='Monty is not.'))
      # -> "Python is fun!"

print(cfg.get('Section1', 'monster', fallback='No such things as monsters.'))
      # -> "No such things as monsters."

# A bare print(cfg.get('Section1', 'monster')) would raise NoOptionError
# but we can also use:

print(cfg.get('Section1', 'monster', fallback=None))
      # -> None

Default values are available in both types of ConfigParsers. They are used in interpolation if an option used is not defined elsewhere.

import configparser

# New instance with 'bar' and 'baz' defaulting to 'Life' and 'hard' each
config = configparser.ConfigParser({'bar': 'Life', 'baz': 'hard'})
config.read('example.cfg')

print(config.get('Section1', 'foo')) # -> "Python is fun!"
config.remove_option('Section1', 'bar')
config.remove_option('Section1', 'baz')
print(config.get('Section1', 'foo')) # -> "Life is hard!"

14.2.9. ConfigParser Objects¶

class configparser.ConfigParser(defaults=None, dict_type=collections.OrderedDict, allow_no_value=False, delimiters=('=', ':'), comment_prefixes=('#', ';'), inline_comment_prefixes=None, strict=True, empty_lines_in_values=True, default_section=configparser.DEFAULTSECT, interpolation=BasicInterpolation(), converters={})¶

The main configuration parser. When defaults is given, it is initialized into the dictionary of intrinsic defaults. When dict_type is given, it will be used to create the dictionary objects for the list of sections, for the options within a section, and for the default values.

When delimiters is given, it is used as the set of substrings that divide keys from values. When comment_prefixes is given, it will be used as the set of substrings that prefix comments in otherwise empty lines. Comments can be indented. When inline_comment_prefixes is given, it will be used as the set of substrings that prefix comments in non-empty lines.

When strict is True (the default), the parser won’t allow for any section or option duplicates while reading from a single source (file, string or dictionary), raising DuplicateSectionError or DuplicateOptionError. When empty_lines_in_values is False (default: True), each empty line marks the end of an option. Otherwise, internal empty lines of a multiline option are kept as part of the value. When allow_no_value is True (default: False), options without values are accepted; the value held for these is None and they are serialized without the trailing delimiter.

When default_section is given, it specifies the name for the special section holding default values for other sections and interpolation purposes (normally named "DEFAULT"). This value can be retrieved and changed on runtime using the default_section instance attribute.

Interpolation behaviour may be customized by providing a custom handler through the interpolation argument. None can be used to turn off interpolation completely, ExtendedInterpolation() provides a more advanced variant inspired by zc.buildout. More on the subject in the dedicated documentation section.

All option names used in interpolation will be passed through the optionxform() method just like any other option name reference. For example, using the default implementation of optionxform() (which converts option names to lower case), the values foo %(bar)s and foo %(BAR)s are equivalent.

When converters is given, it should be a dictionary where each key represents the name of a type converter and each value is a callable implementing the conversion from string to the desired datatype. Every converter gets its own corresponding get*() method on the parser object and section proxies.

Changed in version 3.1: The default dict_type is collections.OrderedDict.

Changed in version 3.2: allow_no_value, delimiters, comment_prefixes, strict, empty_lines_in_values, default_section and interpolation were added.

Changed in version 3.5: The converters argument was added.

defaults()¶: Return a dictionary containing the instance-wide defaults.

sections()¶: Return a list of the sections available; the default section is not included in the list.

add_section(section)¶: Add a section named section to the instance. If a section by the given name already exists, DuplicateSectionError is raised. If the default section name is passed, ValueError is raised. The name of the section must be a string; if not, TypeError is raised.

Changed in version 3.2: Non-string section names raise TypeError.

has_section(section)¶: Indicates whether the named section is present in the configuration. The default section is not acknowledged.

options(section)¶: Return a list of options available in the specified section.

has_option(section, option)¶: If the given section exists, and contains the given option, return True; otherwise return False. If the specified section is None or an empty string, DEFAULT is assumed.

read(filenames, encoding=None)¶

Attempt to read and parse a list of filenames, returning a list of filenames which were successfully parsed. If filenames is a string, it is treated as a single filename. If a file named in filenames cannot be opened, that file will be ignored. This is designed so that you can specify a list of potential configuration file locations (for example, the current directory, the user’s home directory, and some system-wide directory), and all existing configuration files in the list will be read. If none of the named files exist, the ConfigParser instance will contain an empty dataset. An application which requires initial values to be loaded from a file should load the required file or files using read_file() before calling read() for any optional files:

import configparser, os

config = configparser.ConfigParser()
config.read_file(open('defaults.cfg'))
config.read(['site.cfg', os.path.expanduser('~/.myapp.cfg')],
            encoding='cp1250')

New in version 3.2: The encoding parameter. Previously, all files were read using the default encoding for open().

read_file(f, source=None)¶

Read and parse configuration data from f which must be an iterable yielding Unicode strings (for example files opened in text mode).

Optional argument source specifies the name of the file being read. If not given and f has a name attribute, that is used for source; the default is '<???>'.

New in version 3.2: Replaces readfp().

read_string(string, source='<string>')¶

Parse configuration data from a string.

Optional argument source specifies a context-specific name of the string passed. If not given, '<string>' is used. This should commonly be a filesystem path or a URL.

New in version 3.2.

read_dict(dictionary, source='<dict>')¶

Load configuration from any object that provides a dict-like items() method. Keys are section names, values are dictionaries with keys and values that should be present in the section. If the used dictionary type preserves order, sections and their keys will be added in order. Values are automatically converted to strings.

Optional argument source specifies a context-specific name of the dictionary passed. If not given, <dict> is used.

This method can be used to copy state between parsers.

New in version 3.2.

get(section, option, *, raw=False, vars=None[, fallback])¶

Get an option value for the named section. If vars is provided, it must be a dictionary. The option is looked up in vars (if provided), section, and in DEFAULTSECT in that order. If the key is not found and fallback is provided, it is used as a fallback value. None can be provided as a fallback value.

All the '%' interpolations are expanded in the return values, unless the raw argument is true. Values for interpolation keys are looked up in the same manner as the option.

Changed in version 3.2: Arguments raw, vars and fallback are keyword only to protect users from trying to use the third argument as the fallback fallback (especially when using the mapping protocol).

getint(section, option, *, raw=False, vars=None[, fallback])¶: A convenience method which coerces the option in the specified section to an integer. See get() for explanation of raw, vars and fallback.

getfloat(section, option, *, raw=False, vars=None[, fallback])¶: A convenience method which coerces the option in the specified section to a floating point number. See get() for explanation of raw, vars and fallback.

getboolean(section, option, *, raw=False, vars=None[, fallback])¶: A convenience method which coerces the option in the specified section to a Boolean value. Note that the accepted values for the option are '1', 'yes', 'true', and 'on', which cause this method to return True, and '0', 'no', 'false', and 'off', which cause it to return False. These string values are checked in a case-insensitive manner. Any other value will cause it to raise ValueError. See get() for explanation of raw, vars and fallback.

items(raw=False, vars=None)¶

items(section, raw=False, vars=None)

When section is not given, return a list of section_name, section_proxy pairs, including DEFAULTSECT.

Otherwise, return a list of name, value pairs for the options in the given section. Optional arguments have the same meaning as for the get() method.

Changed in version 3.2: Items present in vars no longer appear in the result. The previous behaviour mixed actual parser options with variables provided for interpolation.

set(section, option, value)¶: If the given section exists, set the given option to the specified value; otherwise raise NoSectionError. option and value must be strings; if not, TypeError is raised.

write(fileobject, space_around_delimiters=True)¶: Write a representation of the configuration to the specified file object, which must be opened in text mode (accepting strings). This representation can be parsed by a future read() call. If space_around_delimiters is true, delimiters between keys and values are surrounded by spaces.

remove_option(section, option)¶: Remove the specified option from the specified section. If the section does not exist, raise NoSectionError. If the option existed to be removed, return True; otherwise return False.

remove_section(section)¶: Remove the specified section from the configuration. If the section in fact existed, return True. Otherwise return False.

optionxform(option)¶

Transforms the option name option as found in an input file or as passed in by client code to the form that should be used in the internal structures. The default implementation returns a lower-case version of option; subclasses may override this or client code can set an attribute of this name on instances to affect this behavior.

You don’t need to subclass the parser to use this method, you can also set it on an instance, to a function that takes a string argument and returns a string. Setting it to str, for example, would make option names case sensitive:

cfgparser = ConfigParser()
cfgparser.optionxform = str

Note that when reading configuration files, whitespace around the option names is stripped before optionxform() is called.

readfp(fp, filename=None)¶

Deprecated since version 3.2: Use read_file() instead.

Changed in version 3.2: readfp() now iterates on f instead of calling f.readline().

For existing code calling readfp() with arguments which don’t support iteration, the following generator may be used as a wrapper around the file-like object:

def readline_generator(f):
    line = f.readline()
    while line:
        yield line
        line = f.readline()

Instead of parser.readfp(f) use parser.read_file(readline_generator(f)).

configparser.MAX_INTERPOLATION_DEPTH¶: The maximum depth for recursive interpolation for get() when the raw parameter is false. This is relevant only when the default interpolation is used.

14.2.10. RawConfigParser Objects¶

class configparser.RawConfigParser(defaults=None, dict_type=collections.OrderedDict, allow_no_value=False, *, delimiters=('=', ':'), comment_prefixes=('#', ';'), inline_comment_prefixes=None, strict=True, empty_lines_in_values=True, default_section=configparser.DEFAULTSECT[, interpolation])¶

Legacy variant of the ConfigParser with interpolation disabled by default and unsafe add_section and set methods.

Note

Consider using ConfigParser instead which checks types of the values to be stored internally. If you don’t want interpolation, you can use ConfigParser(interpolation=None).

add_section(section)¶

Add a section named section to the instance. If a section by the given name already exists, DuplicateSectionError is raised. If the default section name is passed, ValueError is raised.

Type of section is not checked which lets users create non-string named sections. This behaviour is unsupported and may cause internal errors.

set(section, option, value)¶

If the given section exists, set the given option to the specified value; otherwise raise NoSectionError. While it is possible to use RawConfigParser (or ConfigParser with raw parameters set to true) for internal storage of non-string values, full functionality (including interpolation and output to files) can only be achieved using string values.

This method lets users assign non-string values to keys internally. This behaviour is unsupported and will cause errors when attempting to write to a file or get it in non-raw mode. Use the mapping protocol API which does not allow such assignments to take place.

14.2.11. Exceptions¶

exception configparser.Error¶: Base class for all other configparser exceptions.

exception configparser.NoSectionError¶: Exception raised when a specified section is not found.

exception configparser.DuplicateSectionError¶: Exception raised if add_section() is called with the name of a section that is already present or in strict parsers when a section if found more than once in a single input file, string or dictionary.

New in version 3.2: Optional source and lineno attributes and arguments to __init__() were added.

exception configparser.DuplicateOptionError¶: Exception raised by strict parsers if a single option appears twice during reading from a single file, string or dictionary. This catches misspellings and case sensitivity-related errors, e.g. a dictionary may have two keys representing the same case-insensitive configuration key.

exception configparser.NoOptionError¶: Exception raised when a specified option is not found in the specified section.

exception configparser.InterpolationError¶: Base class for exceptions raised when problems occur performing string interpolation.

exception configparser.InterpolationDepthError¶: Exception raised when string interpolation cannot be completed because the number of iterations exceeds MAX_INTERPOLATION_DEPTH. Subclass of InterpolationError.

exception configparser.InterpolationMissingOptionError¶: Exception raised when an option referenced from a value does not exist. Subclass of InterpolationError.

exception configparser.InterpolationSyntaxError¶: Exception raised when the source text into which substitutions are made does not conform to the required syntax. Subclass of InterpolationError.

exception configparser.MissingSectionHeaderError¶: Exception raised when attempting to parse a file which has no section headers.

exception configparser.ParsingError¶: Exception raised when errors occur attempting to parse a file.

Changed in version 3.2: The filename attribute and __init__() argument were renamed to source for consistency.

Footnotes

[1]	(1, 2, 3, 4, 5, 6, 7, 8, 9, 10) Config parsers allow for heavy customization. If you are interested in changing the behaviour outlined by the footnote reference, consult the Customizing Parser Behaviour section.

14.2. `configparser` — Configuration file parser¶

14.2.1. Quick Start¶

14.2.2. Supported Datatypes¶

14.2.3. Fallback Values¶

14.2.4. Supported INI File Structure¶

14.2.5. Interpolation of values¶

14.2.6. Mapping Protocol Access¶

14.2.7. Customizing Parser Behaviour¶

14.2.8. Legacy API Examples¶

14.2.9. ConfigParser Objects¶

14.2.10. RawConfigParser Objects¶

14.2.11. Exceptions¶

Table Of Contents

Previous topic

Next topic

This Page

14.2. configparser — Configuration file parser¶

14.2.1. Quick Start¶

14.2.2. Supported Datatypes¶

14.2.3. Fallback Values¶

14.2.4. Supported INI File Structure¶

14.2.5. Interpolation of values¶

14.2.6. Mapping Protocol Access¶

14.2.7. Customizing Parser Behaviour¶

14.2.8. Legacy API Examples¶

14.2.9. ConfigParser Objects¶

14.2.10. RawConfigParser Objects¶

14.2.11. Exceptions¶

14.2. `configparser` — Configuration file parser¶