JSON Object in python

JSON Object in python

let start for the basic and the well know definition of what is JSON

JSON stand for Java Script Object Notation and it is a light weight data format with many similarities to python dictionaries. JSON objects can be parse by many, if not all, modern browsers, which is ideal for transporting data between a client and a server.

Defining a JSON

First let make and example file, that can be copy and save as a .txt and it will represent our JSON file

{
     "album_title" : "Yellow Submarine",
     "release_year" : 1966,
     "won_grammy" : false,
     "band" : "The Beatles",
     "album_sale": null,
     "musicians" : ["John Lennon", "Paul McCartney", "George   Harrison", "Ringo Starr"],
     "studio" : {"studio_name": "Abbey Road Studios", "location": "London, England"}
     }

First, what we know, the keys are strings and the values can be strings, numbers (floats or ints), boolean values, lists, null, or another JSON object. second, what are the difference with Python dictionaries; A JSON objects, for example, represent the boolean values as lower case and empty values are null.

A python dictionary equivalent is:

{
     "album_title" : "Yellow Submarine",
     "release_year" : 1966,
     "won_grammy" : False,
     "band" : "The Beatles",
     "album_sale": None,
     "musicians" : ["John Lennon", "Paul McCartney", "George   Harrison", "Ringo Starr"],
     "studio" : {"studio_name": "Abbey Road Studios", "location": "London, England"}
     }

Notice that in python dictionaries boolean values are capitalize and empty value are None

I will save this JSON in a .txt and called 'album.txt', later import json library and use dir() to check the available methods:

import json
print(dir(json))

load() and dump()

We will focus in load() and dump() methods, for that we will open the file, and album.txt that contain a JSON object, we will open this file using open() and we can choose if open in writing mode or reading mode, this case will be reading so the second argument will be 'r'

import json as j

album_json_file = open("album.TXT",'r')
album = j.load(album_json_file)
print(album)

if we use print(type(album)) the result will be a python dictionary type

\[ <class 'dict'> \]

We can verify this by checking two values, the value of ‘won_grammy’ that now is False and the value of ‘album_sale’ that now is None.

Not that is parse as a dictionary we can call the different values as a dictionary:

print("Album Title: ", album['album_title'])

or

print("Release Year: ", album['release_year'])

JSON in a string form and the method loads()

In client server applications it is common for JSON objects to arrive in the form of strings. For example, our JSON object for album information can look something like this:

album_string = """{"album_title" : "Yellow Submarine",
     "release_year" : 1966,
     "won_grammy" : false,
     "band" : "The Beatles",
     "album_sale": null,
     "musicians" : ["John Lennon", "Paul McCartney", "George   Harrison", "Ringo Starr"],
     "studio" : {"studio_name": "Abbey Road Studios", "location": "London, England"}
     }"""

To load this data using the JSON module, we use the loads() method:

album_s = json.loads(album_string)
album_string.close()
print(album_s)

Now, suppose we start with dictionary formatted data and wish to send this data to a database in JSON format.

We can use the dumps() methods to convert dictionaries to string JSON objects.

album2 = {'album_title': 'Yellow Submarine', 'release_year': 1966, 'won_grammy': False,
 'band': 'The Beatles', 'album_sale': None, 'musicians': ['John Lennon', 'Paul McCartney', 'George   Harrison', 'Ringo Starr'],
 'studio': {'studio_name': 'Abbey Road Studios', 'location': 'London, England'}}
print(json.dumps(album2))
print(type(json.dumps(album2)))

We see that the ‘album_sale’ value, ‘None’, is now ‘null’ and the ‘won_grammy’ value, ‘False’, is now ‘false’.

Finally, we can write this JSON object to a ‘.txt’ file using the dump method:

file2 = open("album2.txt", "w")
json.dump(album2, file2)