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Python Loading JSON config file on __init__

I am new to Python and I am trying to create a class that handles loading my config values.
So far this is what I have :

import os, json

class ConfigHandler:
    CONFIG_FILE = "/config.json"

    def __init__(self):
        print("init config")
        if os.path.exists(self.CONFIG_FILE):
            print("Loading config file")
            self.__dict__ = json.load(open(self.CONFIG_FILE))
        else:
            print("Config file not loaded")

Then in my main application class, I am doing :

from ConfigHandler import ConfigHandler
class MainApp:
     config =  ???

I have tried several ways to get the ConfigHandler to initialize, but it never hits the print statements. And I am not sure how to call the confighandler to get the dictionary.
Any help is appreciated!

Tags:

2

Answers


  1. 0

    Given config.json in the root of your drive if using CONFIG_FILE = "/config.json":

    {
  "a": 1,
  "b": 2,
  "c": "Mark"
}

    Then:

    from ConfigHandler import ConfigHandler

config = ConfigHandler()  # Create an instance...calls __init__ implictly
print(config.a, config.b, config.c)

    Will output:

    1 2 Mark
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  2. 0

    Configure your object with a dict, and provide a separate class method for obtaining that dict from a JSON file.

    class ConfigHandler:    
    def __init__(self, d):
        self.__dict__ = d

    @classmethod
    def from_json(cls, fh):
        return cls(json.load(fh))

    Note, too, that the caller should be responsible for opening the file, not your ConfigHandler class.

    with open("config.json") as f:
    c = ConfigHandler.from_json(f)
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