How to Convert a JSON String to CSV Using Python?

The data can be stored in a variety of formats, including XML, JSON, and CSV. Sometimes, it is required to convert data from one format to another, for example, to import data into a database, to make it more accessible to a wider range of applications, etc. Python provides numerous modules and functions to convert one data format into a different format.

This tutorial will explain different methods to convert JSON strings to CSV files using Python. The below content will be discussed with numerous examples:

Method 1: Using Pandas Module
Method 2: Using CSV and JSON Module

Method 1: Using Pandas Module

The pandas module provides a function named “pd.read_json()” and “df.to_csv()” to read and write a JSON string to a CSV file in Python.

The below code uses the “pandas.read_json()” function of the Pandas module to convert JSON string to CSV file:

Code:

import pandas
json_value = '[{"Name": "Joseph", "Age": 23, "Height": 5.7}, {"Name": "Lily", "Age": 22, "Height": 6.7},{"Name": "Alex", "Age": 25, "Height": 5.6},{"Name": "Henry", "Age": 24, "Height": 6.1}]'
data_frame = pandas.read_json(json_value)
data_frame.to_csv('file.csv')

The “pandas” module is imported into the program.
The JSON string is initialized and assigned in a variable called “json_value”.
The “pd.read_json()” takes the JSON string as an argument and returns the DataFrame object.
The “df.to_csv()” function is used to write a DataFrame object to a CSV file named “file.csv”

Output:

The given JSON string has been converted into a CSV file.

Method 2: Using CSV and JSON Module

To convert the JSON string to a CSV file you can use the “csv.writer()” function of the CSV module and the “json.loads()” function of the JSON module.

Here is an example:

Code:

import json
import csv
json_value = '[{"Name": "Joseph", "Age": 23, "Height": 5.7}, {"Name": "Lily", "Age": 22, "Height": 6.7},{"Name": "Alex", "Age": 25, "Height": 5.6},{"Name": "Henry", "Age": 24, "Height": 6.1}]'
json_object = json.loads(json_value)
with open('output.csv', 'w', newline='') as f:
    writer = csv.writer(f)
    writer.writerow(json_object[0].keys())
    for row in json_object:
        writer.writerow(row.values())

In the above code, we import the json and csv modules.
The json string is initialized and assigned to a variable called “json_value”.
The “json.loads()” function accepts the JSON string object and transforms it into a Python object.
A “CSV” file named “output.csv” is opened/created in “w” (write) mode using the “with open()” function.
The “csv.writer()” function takes the file object and writes data to a CSV file.
The keys() method returns the keys of the object placed at the first index in the JSON array which is passed to the “writerow()” function.
The “writerow()” function accepts the first object of the json array and writes the header/first row to the CSV file named “output.csv”.
The for loop is used to iterate through each object in the JSON array and write the values to the CSV file using the “row.values()” method.
The first row of the CSV file contains the header values, which are the keys of the first object in the JSON list.

Output:

The JSON string has been converted into a CSV file.

Conclusion

The “pd.read_json()” and “df.to_csv()” functions of the Pandas module are used to convert/transform the JSON string to a CSV file in Python. The “pd.read_json()” function is used along with the“df.to_csv()” function to read the JSON data and convert the dataframe to the CSV file. Similarly, the “json.loads()” function parses the JSON data to a Python object, and the “csv.writer()” function writes the Python object to the CSV file. This guide provides various methods to convert JSON strings to CSV using appropriate examples in Python.

Joseph