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I am currently using the Python library configparser:

from configparser import ConfigParser, ExtendedInterpolation

I find the ExtendedInterpolation very useful because it avoids the risk of having to reenter constants in multiple places.

I now have a requirement to use a Json document as the basis of the configuration as it provides more structure.

import json
from collections import OrderedDict

def get_json_config(file):
    """Load Json into OrderedDict from file"""

    with open(file) as json_data:
        d = json.load(json_data, object_pairs_hook=OrderedDict)

    return d

Does anyone have any suggestions as to the best way to implement configparser style ExtendedInterpolation?

For example if a node in the Json contains the value ${home_dir}/lumberjack this would copy root node home_dir and take value 'lumberjack'?

user2579685
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2 Answers2

1

Try to use string.Template. But I'm not sure whether it's your need. There is one package can do this may be. Bellow is what i should do.

config.json

{
    "home_dir": "/home/joey",
    "class_path": "/user/local/bin",
    "dir_one": "${home_dir}/dir_one", 
    "dir_two": "${home_dir}/dir_two", 

    "sep_path_list": [
        "${class_path}/python",
        "${class_path}/ruby",
        "${class_path}/php"
    ]
}

python code:

import json
from string import Template

with open("config.json", "r") as config_file:
    config_content = config_file.read()
    config_template = Template(config_content)
    mid_json = json.loads(config_content)
    config = config_template.safe_substitute(mid_json)

    print config

This can substitute the defined key in json file.

Joey.Chang
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0

Came in very useful; however, I found "config" is a unicode string; I resolved with:

# proper code
return json.loads(config)
Rob Ert
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user1453863
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