Flattening JSON objects in Python

JSON(JavaScript Object Notation) is a data-interchange format that is human-readable text and is used to transmit data, especially between web applications and servers. The JSON files will be like nested dictionaries in Python. To convert a text file into JSON, there is a json module in Python. This module comes in-built with Python standard modules, so there is no need to install it externally.

A flatten json is nothing but there is no nesting is present and only key-value pairs are present.

Example:

Unflattened JSON:
{‘user’ :{‘Rachel’:{‘UserID’:1717171717,
‘Email’: ‘rachel1999@gmail.com’,
‘friends’: [‘John’, ‘Jeremy’, ‘Emily’]}}}

Flattened JSON:
{‘user_Rachel_friends_2’: ‘Emily’, ‘user_Rachel_friends_0’: ‘John’, ‘user_Rachel_UserID’: 1717171717, ‘user_Rachel_Email’: ‘rachel1999@gmail.com’, ‘user_Rachel_friends_1’: ‘Jeremy’}

Need of flattening JSON

There are many reasons for the need of flattening JSON, such as for a better and understandable view that is there are only key-value pairs are present without any nesting. It also allows for context-specific security and constraints to be implemented in a readable, but in more verbose way.

Approach to flatten JSON

There are many ways to flatten JSON. There is one recursive way and another by using the json-flatten library.

• Recursive Approach: Now we can flatten the dictionary array by a recursive approach which is quite easy to understand. The recursive approach is a bit slower than using json-flatten library.

  Example:

  
  

  
  
  

  # for a array value of a key unflat_json = {'user' :                {'Rachel':                 {'UserID':1717171717,                 'Email': 'rachel1999@gmail.com',                  'friends': ['John', 'Jeremy', 'Emily']                 }                }               }    # Function for flattening  # json def flatten_json(y):     out = {}        def flatten(x, name =''):                    # If the Nested key-value          # pair is of dict type         if type(x) is dict:                            for a in x:                 flatten(x[a], name + a + '_')                            # If the Nested key-value         # pair is of list type         elif type(x) is list:                            i = 0                            for a in x:                                 flatten(a, name + str(i) + '_')                 i += 1         else:             out[name[:-1]] = x        flatten(y)     return out    # Driver code print(flatten_json(unflat_json))

  Output :

  {‘user_Rachel_friends_2’: ‘Emily’, ‘user_Rachel_friends_0’: ‘John’, ‘user_Rachel_UserID’: 1717171717, ‘user_Rachel_Email’: ‘rachel1999@gmail.com’, ‘user_Rachel_friends_1’: ‘Jeremy’}

• Using flatten_json library: json-flatten library provides functions for flattening a JSON object to a single key-value pairs, and unflattening that dictionary back to a JSON object.

  Installing library

  In order to use the flatten_json library, we need to install this library. flatten_json can be installed by running the following command in the terminal.

  pip install json-flatten

  Example:

  
  

  
  
  

  from flatten_json import flatten    unflat_json = {'user' :                {'Rachel':                 {'UserID':1717171717,                 'Email': 'rachel1999@gmail.com',                  'friends': ['John', 'Jeremy', 'Emily']                 }                }               }    flat_json = flatten(unflat_json)    print(flat_json)

  Output :

  {‘user_Rachel_UserID’: 1717171717, ‘user_Rachel_Email’: ‘rachel1999@gmail.com’, ‘user_Rachel_friends_0’: ‘John’, ‘user_Rachel_friends_1’: ‘Jeremy’, ‘user_Rachel_friends_2’: ‘Emily’}