Python Core | VoidX Academy

21. Python JSON

Data Processing

Python JSON

JSON (JavaScript Object Notation) is a syntax for storing and exchanging data. It is text-based, lightweight, and language-independent, making it the universal standard for data exchange on the web (APIs). If your Python script talks to a server, it will almost certainly be using JSON.

Python has a built-in package called json, which allows you to seamlessly convert JSON strings into Python dictionaries, and vice-versa.

Importing the json Module

Since JSON support is built directly into Python's standard library, you do not need to install anything. Just import the module.

import json

print("JSON module is ready to use!")

OutputJSON module is ready to use!

Parse JSON (JSON to Python)

If you receive a JSON string (for example, from a web API request), you can parse it by using the json.loads() method (loads stands for "load string"). The result will be a native Python dictionary.

import json

# Some JSON data: literally just a text string
x = '{"name": "John", "age": 30, "city": "New York"}'

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

# The result is a Python dictionary:
print(y["age"])
print(type(y))

Output30 <class 'dict'>

Convert Python to JSON

If you have a Python object (a dictionary, list, etc.), you can convert it into a JSON string by using the json.dumps() method (dumps stands for "dump string"). This is necessary before sending data over a network.

import json

# A Python dictionary
x = {
  "name": "John",
  "age": 30,
  "city": "New York"
}

# Convert into JSON:
y = json.dumps(x)

# The result is a JSON string:
print(y)
print(type(y))

Output{"name": "John", "age": 30, "city": "New York"} <class 'str'>

What Types Can Be Converted?

You can convert Python objects of the following types, into JSON strings:

dict (converts to JSON Object)
list, tuple (converts to JSON Array)
str (converts to JSON String)
int, float (converts to JSON Number)
True, False (converts to JSON true, false)
None (converts to JSON null)

import json

print(json.dumps(["apple", "bananas"]))
print(json.dumps(("apple", "bananas")))
print(json.dumps("hello"))
print(json.dumps(42))
print(json.dumps(31.76))
print(json.dumps(True))
print(json.dumps(None))

Output["apple", "bananas"] ["apple", "bananas"] "hello" 42 31.76 true null

Formatting JSON (indent)

By default, json.dumps() outputs a dense string with no spaces, which is hard to read. Use the indent parameter to define the number of indents, creating beautifully formatted, human-readable JSON.

import json

x = {
  "name": "John",
  "age": 30,
  "married": True,
  "pets": ["dog", "cat"]
}

# Use indent=4 to format the JSON string
print(json.dumps(x, indent=4))

Output{ "name": "John", "age": 30, "married": true, "pets": [ "dog", "cat" ] }

Sorting the Results

When you have a massive dictionary, finding specific keys can be tough. You can tell json.dumps() to sort the keys alphabetically using the sort_keys parameter.

import json

x = {
  "name": "John",
  "age": 30,
  "married": True,
  "city": "New York"
}

print(json.dumps(x, indent=2, sort_keys=True))

Output{ "age": 30, "city": "New York", "married": true, "name": "John" }

💡File Handling: The methods json.loads() and json.dumps() work with strings. If you want to read from or write directly to a file, use json.load(file) and json.dump(obj, file) without the 's'.

21. Python JSON

Data Processing

Python JSON

Python has a built-in package called json, which allows you to seamlessly convert JSON strings into Python dictionaries, and vice-versa.

Importing the json Module

Since JSON support is built directly into Python's standard library, you do not need to install anything. Just import the module.

import json

print("JSON module is ready to use!")

OutputJSON module is ready to use!

Parse JSON (JSON to Python)

import json

# Some JSON data: literally just a text string
x = '{"name": "John", "age": 30, "city": "New York"}'

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

# The result is a Python dictionary:
print(y["age"])
print(type(y))

Output30 <class 'dict'>

Convert Python to JSON

import json

# A Python dictionary
x = {
  "name": "John",
  "age": 30,
  "city": "New York"
}

# Convert into JSON:
y = json.dumps(x)

# The result is a JSON string:
print(y)
print(type(y))

Output{"name": "John", "age": 30, "city": "New York"} <class 'str'>

What Types Can Be Converted?

You can convert Python objects of the following types, into JSON strings:

dict (converts to JSON Object)
list, tuple (converts to JSON Array)
str (converts to JSON String)
int, float (converts to JSON Number)
True, False (converts to JSON true, false)
None (converts to JSON null)

import json

print(json.dumps(["apple", "bananas"]))
print(json.dumps(("apple", "bananas")))
print(json.dumps("hello"))
print(json.dumps(42))
print(json.dumps(31.76))
print(json.dumps(True))
print(json.dumps(None))

Output["apple", "bananas"] ["apple", "bananas"] "hello" 42 31.76 true null

Formatting JSON (indent)

import json

x = {
  "name": "John",
  "age": 30,
  "married": True,
  "pets": ["dog", "cat"]
}

# Use indent=4 to format the JSON string
print(json.dumps(x, indent=4))

Output{ "name": "John", "age": 30, "married": true, "pets": [ "dog", "cat" ] }

Sorting the Results

When you have a massive dictionary, finding specific keys can be tough. You can tell json.dumps() to sort the keys alphabetically using the sort_keys parameter.

import json

x = {
  "name": "John",
  "age": 30,
  "married": True,
  "city": "New York"
}

print(json.dumps(x, indent=2, sort_keys=True))

Output{ "age": 30, "city": "New York", "married": true, "name": "John" }

21. Python JSON

Python JSON

Importing the json Module

Parse JSON (JSON to Python)

Convert Python to JSON

What Types Can Be Converted?

Formatting JSON (indent)

Sorting the Results

Knowledge Check

21. Python JSON

Python JSON

Importing the json Module

Parse JSON (JSON to Python)

Convert Python to JSON

What Types Can Be Converted?

Formatting JSON (indent)

Sorting the Results

Knowledge Check