Lists in ConfigParser

Python Problem Overview

The typical ConfigParser generated file looks like:

[Section]
bar=foo
[Section 2]
bar2= baz

Now, is there a way to index lists like, for instance:

[Section 3]
barList={
    item1,
    item2
}

Python Solutions

Solution 1 - Python

I am using a combination of ConfigParser and JSON:

[Foo]
fibs: [1,1,2,3,5,8,13]

just read it with:

>>> json.loads(config.get("Foo","fibs"))
[1, 1, 2, 3, 5, 8, 13]

You can even break lines if your list is long (thanks @peter-smit):

[Bar]
files_to_check = [
     "/path/to/file1",
     "/path/to/file2",
     "/path/to/another file with space in the name"
     ]

Of course i could just use JSON, but i find config files much more readable, and the [DEFAULT] Section very handy.

Solution 2 - Python

There is nothing stopping you from packing the list into a delimited string and then unpacking it once you get the string from the config. If you did it this way your config section would look like:

[Section 3]
barList=item1,item2

It's not pretty but it's functional for most simple lists.

Solution 3 - Python

I recently implemented this with a dedicated section in a config file for a list:

[paths]
path1			= /some/path/
path2			= /another/path/
...

and using config.items( "paths" ) to get an iterable list of path items, like so:

path_items = config.items( "paths" )
for key, path in path_items:
    #do something with path

Hope this helps other folk Googling this question ;)

Solution 4 - Python

One thing a lot of people don't know is that multi-line configuration-values are allowed. For example:

;test.ini
[hello]
barlist = 
    item1
    item2

The value of config.get('hello','barlist') will now be:

"\nitem1\nitem2"

Which you easily can split with the splitlines method (don't forget to filter empty items).

If we look to a big framework like Pyramid they are using this technique:

def aslist_cronly(value):
    if isinstance(value, string_types):
        value = filter(None, [x.strip() for x in value.splitlines()])
    return list(value)

def aslist(value, flatten=True):
    """ Return a list of strings, separating the input based on newlines
    and, if flatten=True (the default), also split on spaces within
    each line."""
    values = aslist_cronly(value)
    if not flatten:
        return values
    result = []
    for value in values:
        subvalues = value.split()
        result.extend(subvalues)
    return result

Source

Myself, I would maybe extend the ConfigParser if this is a common thing for you:

class MyConfigParser(ConfigParser):
    def getlist(self,section,option):
        value = self.get(section,option)
        return list(filter(None, (x.strip() for x in value.splitlines())))

    def getlistint(self,section,option):
        return [int(x) for x in self.getlist(section,option)]

Note that there are a few things to look out for when using this technique

New lines that are items should start with whitespace (e.g. a space or a tab)
All following lines that start with whitespace are considered to be part of the previous item. Also if it has an = sign or if it starts with a ; following the whitespace.

Solution 5 - Python

If you want to literally pass in a list then you can use:

ast.literal_eval()

For example configuration:

[section]
option=["item1","item2","item3"]

The code is:

import ConfigParser
import ast

my_list = ast.literal_eval(config.get("section", "option"))
print(type(my_list))
print(my_list)

output:

<type'list'>
["item1","item2","item3"]

Solution 6 - Python

No mention of the converters kwarg for ConfigParser() in any of these answers was rather disappointing.

According to the documentation you can pass a dictionary to ConfigParser that will add a get method for both the parser and section proxies. So for a list:

example.ini

[Germ]
germs: a,list,of,names, and,1,2, 3,numbers

Parser example:

cp = ConfigParser(converters={'list': lambda x: [i.strip() for i in x.split(',')]})
cp.read('example.ini')
cp.getlist('Germ', 'germs')
['a', 'list', 'of', 'names', 'and', '1', '2', '3', 'numbers']
cp['Germ'].getlist('germs')
['a', 'list', 'of', 'names', 'and', '1', '2', '3', 'numbers']

This is my personal favorite as no subclassing is necessary and I don't have to rely on an end user to perfectly write JSON or a list that can be interpreted by ast.literal_eval.

Solution 7 - Python

I landed here seeking to consume this...

[global]
spys = [email protected], [email protected]

The answer is to split it on the comma and strip the spaces:

SPYS = [e.strip() for e in parser.get('global', 'spys').split(',')]

To get a list result:

['[email protected]', '[email protected]']

It may not answer the OP's question exactly but might be the simple answer some people are looking for.

Solution 8 - Python

This is what I use for lists:

config file content:

[sect]
alist = a
        b
        c

code :

l = config.get('sect', 'alist').split('\n')

it work for strings

in case of numbers

config content:

nlist = 1
        2
        3

code:

nl = config.get('sect', 'alist').split('\n')
l = [int(nl) for x in nl]

thanks.

Solution 9 - Python

I completed similar task in my project with section with keys without values:

import configparser

# allow_no_value param says that no value keys are ok
config = configparser.ConfigParser(allow_no_value=True)

# overwrite optionxform method for overriding default behaviour (I didn't want lowercased keys)
config.optionxform = lambda optionstr: optionstr

config.read('./app.config')
    
features = list(config['FEATURES'].keys())

print(features)

Output:

['BIOtag', 'TextPosition', 'IsNoun', 'IsNomn']

app.config:

[FEATURES]
BIOtag
TextPosition
IsNoun
IsNomn

Solution 10 - Python

So another way, which I prefer, is to just split the values, for example:

#/path/to/config.cfg
[Numbers]
first_row = 1,2,4,8,12,24,36,48

Could be loaded like this into a list of strings or integers, as follows:

import configparser

config = configparser.ConfigParser()
config.read('/path/to/config.cfg')

# Load into a list of strings
first_row_strings = config.get('Numbers', 'first_row').split(',')

# Load into a list of integers
first_row_integers = [int(x) for x in config.get('Numbers', 'first_row').split(',')]

This method prevents you from needing to wrap your values in brackets to load as JSON.

Solution 11 - Python

Only primitive types are supported for serialization by config parser. I would use JSON or YAML for that kind of requirement.

Solution 12 - Python

To take Grr's answer (my favorite) a step further, instead of enclosing list items in quotes in the .ini file, you can use the map function. This allows you to pythonically specify list item datatypes.

Config file:

[section]
listKey1: 1001, 1002, 1003
listKey2: AAAA, BBBB, CCCC

Code:

cfgFile = 'config.ini'
parser = ConfigParser(converters={'list': lambda x: [i.strip() for i in x.split(',')]})
parser.read(cfgFile)

list1 = list(map(int, parser.getlist('section', 'listKey1')))
list2 = list(map(str, parser.getlist('section', 'listKey2')))

print(list1)
print(list2)

Output:

[1001, 1002, 1003]
['AAAA', 'BBBB', 'CCCC']

Solution 13 - Python

I faced the same problem in the past. If you need more complex lists, consider creating your own parser by inheriting from ConfigParser. Then you would overwrite the get method with that:

    def get(self, section, option):
    """ Get a parameter
    if the returning value is a list, convert string value to a python list"""
    value = SafeConfigParser.get(self, section, option)
    if (value[0] == "[") and (value[-1] == "]"):
        return eval(value)
    else:
        return value

With this solution you will also be able to define dictionaries in your config file.

But be careful! This is not as safe: this means anyone could run code through your config file. If security is not an issue in your project, I would consider using directly python classes as config files. The following is much more powerful and expendable than a ConfigParser file:

class Section
    bar = foo
class Section2
    bar2 = baz
class Section3
    barList=[ item1, item2 ]

Solution 14 - Python

import ConfigParser
import os

class Parser(object):
    """attributes may need additional manipulation"""
    def __init__(self, section):
        """section to retun all options on, formatted as an object
        transforms all comma-delimited options to lists
        comma-delimited lists with colons are transformed to dicts
        dicts will have values expressed as lists, no matter the length
        """
        c = ConfigParser.RawConfigParser()
        c.read(os.path.join(os.path.dirname(__file__), 'config.cfg'))

        self.section_name = section

        self.__dict__.update({k:v for k, v in c.items(section)})

        #transform all ',' into lists, all ':' into dicts
        for key, value in self.__dict__.items():
            if value.find(':') > 0:
                #dict
                vals = value.split(',')
                dicts = [{k:v} for k, v in [d.split(':') for d in vals]]
                merged = {}
                for d in dicts:
                    for k, v in d.items():
                        merged.setdefault(k, []).append(v)
                self.__dict__[key] = merged
            elif value.find(',') > 0:
                #list
                self.__dict__[key] = value.split(',')

So now my config.cfg file, which could look like this:

[server]
credentials=username:admin,password:$3<r3t
loggingdirs=/tmp/logs,~/logs,/var/lib/www/logs
timeoutwait=15

Can be parsed into fine-grained-enough objects for my small project.

>>> import config
>>> my_server = config.Parser('server')
>>> my_server.credentials
{'username': ['admin'], 'password', ['$3<r3t']}
>>> my_server.loggingdirs:
['/tmp/logs', '~/logs', '/var/lib/www/logs']
>>> my_server.timeoutwait
'15'

This is for very quick parsing of simple configs, you lose all ability to fetch ints, bools, and other types of output without either transforming the object returned from Parser, or re-doing the parsing job accomplished by the Parser class elsewhere.

Solution 15 - Python

If this is your config.ini:

[Section 3]
barList=item1,item2

Then with configparser you could do this:

from configparser import ConfigParser
config = ConfigParser()
config.read('config.ini')
my_list = config['Section 3']['barList'].split(',')

You will get:

 my_list =  ['item1', 'item2']

The split()-method will return a list, see Python string docs.

If you have white spaces in your config.ini like this:

[Section 3]
barList= item1, item2

Then you'd better do this:

my_list = [x.strip() for x in config['Section 3']['barList'].split(',')]

If your items are numbers (integers for instance), just apply:

my_list_of_ints = list(map(int, my_list))

You will get:

my_list_of_ints =  [item1, item2]

Solution 16 - Python

json.loads & ast.literal_eval seems to be working but simple list within config is treating each character as byte so returning even square bracket....

meaning if config has fieldvalue = [1,2,3,4,5]

then config.read(*.cfg) config['fieldValue'][0] returning [ in place of 1

Solution 17 - Python

As mentioned by Peter Smit (https://stackoverflow.com/a/11866695/7424596) You might want to extend ConfigParser, in addition, an Interpolator can be used to automatically convert into and from the list.

For reference at the bottom you can find code which automatically converts config like:

[DEFAULT]
keys = [
    Overall cost structure, Capacity, RAW MATERIALS,
    BY-PRODUCT CREDITS, UTILITIES, PLANT GATE COST,
    PROCESS DESCRIPTION, AT 50% CAPACITY, PRODUCTION COSTS,
    INVESTMENT, US$ MILLION, PRODUCTION COSTS, US ¢/LB,
    VARIABLE COSTS, PRODUCTION COSTS, MAINTENANCE MATERIALS
  ]

So if you request keys you will get:

<class 'list'>: ['Overall cost structure', 'Capacity', 'RAW MATERIALS', 'BY-PRODUCT CREDITS', 'UTILITIES', 'PLANT GATE COST', 'PROCESS DESCRIPTION', 'AT 50% CAPACITY', 'PRODUCTION COSTS', 'INVESTMENT', 'US$ MILLION', 'PRODUCTION COSTS', 'US ¢/LB', 'VARIABLE COSTS', 'PRODUCTION COSTS', 'MAINTENANCE MATERIALS']