Python Json

JSON is a syntax for storing and exchanging data, which is text, written with JavaScript object notation

JSON in Python

Python has a built-in package called json, which can be used to work with JSON data

Import

json module can be imported as :

 import json 

Parse JSON - Convert from JSON to Python

A JSON string can be parsed by using the json.loads() method

This returns a Python dictionary

Example

import json
# some JSON
x =  '{ "name":"Johnson", "age":33, "city":"New Jersey"}'

# parse x:
y = json.loads(x)

# the result is a Python dictionary:
print(y) 

Output :

{'name': 'Johnson', 'age': 33, 'city': 'New Jersey'}

Convert from Python to JSON

A Python object can be converted into a JSON string by using the json.dumps() method

Example

import json
# a Python object (dict):
x = {"name": "John","age": 30,"city": "New York" }

# convert into JSON
y = json.dumps(x)

# the result is a JSON string
print(y)

Following types of Python objects can be converted into JSON strings

• dict
• list
• tuple
• string
• int
• float
• True
• False
• None

Python objects are converted into their JSON (JavaScript) equivalent as follows:

Both lists and tuples are converted to arrays

While converting JSON to Python, arrays are converted to lists

Example

 import json
>>> print(json.dumps({"name": "Johnson", "age": 33}))
{"name": "Johnson", "age": 33}
>>> print(json.dumps(["list", "values"]))
["list", "values"]
>>> print(json.dumps(("tuple", "values")))
["tuple", "values"]
>>> print(json.dumps("string"))
"string"
>>> print(json.dumps(42))
42
>>> print(json.dumps(31.76))
31.76
>>> print(json.dumps(True))
true
>>> print(json.dumps(False))
false
>>> print(json.dumps(None))
null

Format the Result

Consider following example

 import json
# Python dict
x = {"name": "Johnson", "age": 33, "married": True, "divorced": False, "languages": ("Python", "Javascript"), "pets": None,
        "children": [ {"name": "Anna", "age": 15}, {"name": "Bil", "age": 11} ]
}
# dump json
print(json.dumps(x)) 

Output

{"name": "Johnson", "age": 33, "married": true, "divorced": false, "languages": ["Python", "Javascript"], "pets": null, "children": [{"name": "Anna", "age": 15}, {"name": "Bil", "age": 11}]}

Above example prints a JSON string, but it does not have indentations and line breaks

The json.dumps()method has parameters to include indentation and separators, to increase readability

Indentation

The indent parameter can be used to define the numbers of indents:

indented = json.dumps(x, indent=4)
print(indented) 

Output

{
    "name": "Johnson",
    "age": 33,
    "married": true,
    "divorced": false,
    "languages": [
        "Python",
        "Javascript"
    ],
    "pets": null,
    "children": [
        {
            "name": "Anna",
            "age": 15
        },
        {
            "name": "Bil",
            "age": 11
        }
    ]
}

Separators

Separators can also be defined, whose default value is (", ", ": "), which means it uses a comma and a space to separate each object, and a colon and a space to separate keys from values

The separators parameter can be used to change the default separator

custom = json.dumps(x, indent=4, separators=(". ", " = "))
print(custom)

Output

{
    "name" = "Johnson".
    "age" = 33.
    "married" = true.
    "divorced" = false.
    "languages" = [
        "Python".
        "Javascript"
    ].
    "pets" = null.
    "children" = [
        {
            "name" = "Anna".
            "age" = 15
        }.
        {
            "name" = "Bil".
            "age" = 11
        }
    ]
}

Sort the Result

json.dumps() method accepts sort_keys parameter to sort the keys in the resultant string

Example

sorted = json.dumps(x, indent=4, sort_keys=True)
print(sorted)

Output

{
    "age": 33,
    "children": [
        {
            "age": 15,
            "name": "Anna"
        },
        {
            "age": 11,
            "name": "Bil"
        }
    ],
    "divorced": false,
    "languages": [
        "Python",
        "Javascript"
    ],
    "married": true,
    "name": "Johnson",
    "pets": null
}

The keys of objects are sorted