How to Append Data to a JSON File in Python

This short article aims to explain how to append data to a JSON file with nested elements. The JSON file is structured in the following way:

If you want to append data to a JSON file in Python, the json module is the way to go. Here’s a step-by-step guide on how to do it:

1. Import the json module at the beginning of your script.

import json

2. Open the JSON file using the open() function.

with open('data.json', 'r') as f:

The first argument is the name of the file and the mode is set to 'r' for reading.

3. Load the data from the JSON file into a Python object using json.load().

data = json.load(f)

This function reads the file and returns a Python object representing the data in the JSON file.

4. Append new data to the Python object.

new_data = {'name': 'John', 'age': 30}
data.append(new_data)

In this example, we’re appending a dictionary with two key-value pairs to the data object.

5. Write the updated object back to the JSON file using json.dump().

with open('data.json', 'w') as f:
    json.dump(data, f)

The first argument is the object you want to write to the file, and the second argument is the file object.

That’s it! You’ve successfully appended data to a JSON file using Python. Just remember that this method assumes that the file already contains a JSON array. If the file contains a single JSON object, you will need to modify the code accordingly.