Convert dict into a config file then restore the dict from config

Question

For example, I have a dictionary in Python like this:

{"a_summary" : 
   {"data1":{"length":100, "quality":10}, 
    "data2":{"length":90, "quality":9}},
"b_summary" :  
   {"data1":{"comments":19, "views":100}, 
    "data2":{"comments":9, "views":4}}}

And then I'd like to convert it into a conf file like this:

[a_summary]
data1_length=100
data1_quality=10
data2_length=90
data2_quality=9

[b_summary]
data1_comments=19
data1_views=100
data2_comments=9
data2_views=4

Though it looks a little weird that data1_ or data2_ is need to represent the nesting, it seems ok now.

But then I need to send this conf file to another user, and he needs to restore the original dictionary from this conf file. It seems that user has to write a few more codes for restoring the dict. However, this solution looks quite dirty.

I was wondering whether there's a Pythonic way for me to save dict into a conf file (if conf file is not suitable, other readable format of plain text is also acceptable) and then restore dict from that plain text file.

Answer 1

Look at configparser module. It could help you to do what you want.

import configparser

data = {"a_summary" : {"data1":{"length":100, "quality":10}, 
            "data2":{"length":90, "quality":9}},
        "b_summary" :  {"data1":{"comments":19, "views":100}, 
            "data2":{"comments":9, "views":4}}}
config = configparser.ConfigParser()
for key1, data1 in data.items():
    config[key1] = {}
    for key2, data2 in data1.items():
        for key3, data3 in data2.items():
            config[key1]["{}_{}".format(key2, key3)] = str(data3)
with open('example.ini', 'w') as configfile:
    config.write(configfile)

And to read again:

config2 = configparser.ConfigParser()
config2.read('example.ini')
data = {}
for key in config2.sections():
    data[key] = {}
    for key2 in config2[key]:
        k1, k2 = key2.split('_')
        if k1 not in data[key]:
            data[key][k1] = {}
        data[key][k1][k2] = int(config2[key][key2])

Answer 2

Save it as JSON perhaps:

import json

with open('configfilename', 'w') as configfile:
    json.dump(yourdict, configfile, indent=2)

I set the json.dump() indentation to make the file reasonably readable.

Load with:

import json

with open('configfilename', 'r') as configfile:
    yourdict = json.load(configfile)

With indent set to 2, your structure would be written out as:

{
  "a_summary": {
    "data1": {
      "length": 100, 
      "quality": 10
    }, 
    "data2": {
      "length": 90, 
      "quality": 9
    }
  }, 
  "b_summary": {
    "data1": {
      "comments": 19, 
      "views": 100
    }, 
    "data2": {
      "comments": 9, 
      "views": 4
    }
  }
}

Answer 3

In case of .ini files, you could use configobj module. To read:

from configobj import ConfigObj
dict = ConfigObj(path)

To save:

from configobj import ConfigObj
config = ConfigObj(dict)
config.filename = "config.ini"
config.write()

Answer 4

It's possible to do this without loops or 3rd party modules.

This will work no matter how deep the dictionary is.

from configparser import ConfigParser

data = {"a_summary" : {"data1":{"length":100, "quality":10}, 
            "data2":{"length":90, "quality":{"q1":1, "q2":{"am": "high", "pm": "low"}}}},
        "b_summary" :  {"data1":{"comments":19, "views":100}, 
            "data2":{"comments":9, "views":4}}}

# dict -> ConfigParser
config = ConfigParser()
config.read_dict(data)
with open('example.ini', 'w') as configfile:
    config.write(configfile)
    
# check result
with open('example.ini', 'r') as configfile2:
    print(configfile2.read())

# ConfigParser -> dict
config2 = ConfigParser()
config2.read('example.ini')
data2 = {section: dict(config2[section]) for section in config2.sections()}
print(data2)