Python JSON – How to Convert a String to JSON (2024)

In this tutorial you'll learn the basics of JSON – what it is, where it is most commonly used, and its syntax.

You'll also see how to convert a string to JSON in Python.

Let's get started!

What is JSON?

JSON stands for JavaScript Object Notation.

It is a data format that's used for storing and transferring information for web applications.

JSON was inspired by the JavaScript programming language, but it's not tied to only one language.

Most modern programming languages have libraries for parsing and generating JSON data.

Where is JSON used?

JSON is mostly used for sending and receiving data between a server and a client, where the client is a webpage or web application.

It's a much more solid format to use during the request-response cycle web applications use when connecting over a network. This is compared to the complicated and less compact XML, which was the format of choice years ago.

Basic JSON syntax

In JSON, data is written in key-value pairs, like so:

"first_name": "Katie"

Data is enclosed in double quotation marks and the key-value pair is separated by a colon.

There can be more than one key-value pair and each one is separated by a comma:

"first_name": "Katie", "last_name": "Rodgers"

The example above showed an object, a collection of multiple key-value pairs.

Objects are inside curly braces:

{ "first_name": "Katie", "last_name": "Rodgers"}

You can also create arrays, an ordered list of values, with JSON. In that case, arrays are contained inside square brackets:

[ { "first_name": "Katie", "last_name": "Rodgers" }, { "first_name": "Naomi", "last_name": "Green" },]// or:{ "employee": [ { "first_name": "Katie", "last_name": "Rodgers" }, { "first_name": "Naomi", "last_name": "Green" }, ]}//this created an 'employee' object that has 2 records.// It defines the first name and last name of an employee

How to work with JSON data in Python

Include the JSON module for Python

To use JSON with Python, you'll first need to include the JSON module at the top of your Python file. This comes built-in to Python and is part of the standard library.

So, say you have a file named demo.py. At the top you would add the following line:

import json

Use the json.loads() function

If you have JSON string data in your program like so:

#include json libraryimport json#json string dataemployee_string = '{"first_name": "Michael", "last_name": "Rodgers", "department": "Marketing"}'#check data type with type() methodprint(type(employee_string))#output#<class 'str'>

you can turn it into JSON in Python using the json.loads() function.

The json.loads() function accepts as input a valid string and converts it to a Python dictionary.

This process is called deserialization – the act of converting a string to an object.

#include json libraryimport json#json string dataemployee_string = '{"first_name": "Michael", "last_name": "Rodgers", "department": "Marketing"}'#check data type with type() methodprint(type(employee_string))#convert string to objectjson_object = json.loads(employee_string)#check new data typeprint(type(json_object))#output#<class 'dict'>

You can then access each individual item, like you would when using a Python dictionary:

#include json libraryimport json#json string dataemployee_string = '{"first_name": "Michael", "last_name": "Rodgers", "department": "Marketing"}'#check data type with type() methodprint(type(employee_string))#convert string to objectjson_object = json.loads(employee_string)#check new data typeprint(type(json_object))#output#<class 'dict'>#access first_name in dictionaryprint(json_object["first_name"])#output#Michael

Let's take another example:

1) Take some JSON string data:

import json#json stringemployees_string = '''{ "employees": [ { "first_name": "Michael", "last_name": "Rodgers", "department": "Marketing" }, { "first_name": "Michelle", "last_name": "Williams", "department": "Engineering" } ]}'''#check data type using the type() methodprint(type(employees_string))#output#<class 'str'>

2) Use the json.loads() function to convert a string to an object:

import jsonemoloyees_string = '''{ "employees" : [ { "first_name": "Michael", "last_name": "Rodgers", "department": "Marketing" }, { "first_name": "Michelle", "last_name": "Williams", "department": "Engineering" } ]}'''data = json.loads(employees_string)print(type(data))#output#<class 'dict'>

3) Access the data:

import jsonemployees_string = '''{ "employees" : [ { "first_name": "Michael", "last_name": "Rodgers", "department": "Marketing" }, { "first_name": "Michelle", "last_name": "Williams", "department": "Engineering" } ]}'''data = json.loads(employees_string)print(type(data))#output#<class 'dict'>#access first_namefor employee in data["employees"]: print(employee["first_name"])#output#Michael#Michelle

Conclusion

And there you have it – you now know the basics of using JSON in Python.

If you want to learn more about Python, freeCodeCamp has a Python Certification which takes you from the fundamentals such as variables, loops, and functions to more advanced concepts such as data structures. In the end you'll also build 5 projects.

Thanks for reading and happy learning!