Using ConfigParser to read a file without section name

I am using ConfigParser to read the runtime configuration of a script.

I would like to have the flexibility of not providing a section name (there are scripts which are simple enough; they don't need a 'section'). ConfigParser will throw a NoSectionError exception, and will not accept the file.

How can I make ConfigParser simply retrieve the (key, value) tuples of a config file without section names?

For instance:

key1=val1
key2:val2

I would rather not write to the config file.

Solution 1:

Alex Martelli provided a solution for using ConfigParser to parse .properties files (which are apparently section-less config files).

His solution is a file-like wrapper that will automagically insert a dummy section heading to satisfy ConfigParser's requirements.

Solution 2:

Enlightened by this answer by jterrace, I come up with this solution:

1. Read entire file into a string
2. Prefix with a default section name
3. Use StringIO to mimic a file-like object

ini_str = '[root]\n' + open(ini_path, 'r').read()
ini_fp = StringIO.StringIO(ini_str)
config = ConfigParser.RawConfigParser()
config.readfp(ini_fp)

EDIT for future googlers: As of Python 3.4+ readfp is deprecated, and StringIO is not needed anymore. Instead we can use read_string directly:

with open('config_file') as f:
    file_content = '[dummy_section]\n' + f.read()

config_parser = ConfigParser.RawConfigParser()
config_parser.read_string(file_content)

Solution 3:

You can do this in a single line of code.

In python 3, prepend a fake section header to your config file data, and pass it to read_string().

from configparser import ConfigParser

parser = ConfigParser()
with open("foo.conf") as stream:
    parser.read_string("[top]\n" + stream.read())  # This line does the trick.

You could also use itertools.chain() to simulate a section header for read_file(). This might be more memory-efficient than the above approach, which might be helpful if you have large config files in a constrained runtime environment.

from configparser import ConfigParser
from itertools import chain

parser = ConfigParser()
with open("foo.conf") as lines:
    lines = chain(("[top]",), lines)  # This line does the trick.
    parser.read_file(lines)

In python 2, prepend a fake section header to your config file data, wrap the result in a StringIO object, and pass it to readfp().

from ConfigParser import ConfigParser
from StringIO import StringIO

parser = ConfigParser()
with open("foo.conf") as stream:
    stream = StringIO("[top]\n" + stream.read())  # This line does the trick.
    parser.readfp(stream)

With any of these approaches, your config settings will be available in parser.items('top').

You could use StringIO in python 3 as well, perhaps for compatibility with both old and new python interpreters, but note that it now lives in the io package and readfp() is now deprecated.

Alternatively, you might consider using a TOML parser instead of ConfigParser.

Solution 4:

You can use the ConfigObj library to do that simply : http://www.voidspace.org.uk/python/configobj.html

Updated: Find latest code here.

If you are under Debian/Ubuntu, you can install this module using your package manager :

apt-get install python-configobj

An example of use:

from configobj import ConfigObj

config = ConfigObj('myConfigFile.ini')
config.get('key1') # You will get val1
config.get('key2') # You will get val2

Solution 5:

The easiest way to do this is to use python's CSV parser, in my opinion. Here's a read/write function demonstrating this approach as well as a test driver. This should work provided the values are not allowed to be multi-line. :)

import csv
import operator

def read_properties(filename):
    """ Reads a given properties file with each line of the format key=value.  Returns a dictionary containing the pairs.

    Keyword arguments:
        filename -- the name of the file to be read
    """
    result={ }
    with open(filename, "rb") as csvfile:
        reader = csv.reader(csvfile, delimiter='=', escapechar='\\', quoting=csv.QUOTE_NONE)
        for row in reader:
            if len(row) != 2:
                raise csv.Error("Too many fields on row with contents: "+str(row))
            result[row[0]] = row[1] 
    return result

def write_properties(filename,dictionary):
    """ Writes the provided dictionary in key-sorted order to a properties file with each line of the format key=value

    Keyword arguments:
        filename -- the name of the file to be written
        dictionary -- a dictionary containing the key/value pairs.
    """
    with open(filename, "wb") as csvfile:
        writer = csv.writer(csvfile, delimiter='=', escapechar='\\', quoting=csv.QUOTE_NONE)
        for key, value in sorted(dictionary.items(), key=operator.itemgetter(0)):
                writer.writerow([ key, value])

def main():
    data={
        "Hello": "5+5=10",
        "World": "Snausage",
        "Awesome": "Possum"
    }

    filename="test.properties"
    write_properties(filename,data)
    newdata=read_properties(filename)

    print "Read in: "
    print newdata
    print

    contents=""
    with open(filename, 'rb') as propfile:
        contents=propfile.read()
    print "File contents:"
    print contents

    print ["Failure!", "Success!"][data == newdata]
    return

if __name__ == '__main__': 
     main()