Python Parse multiple JSON objects from file | Solve ValueError: Extra data

You are here because when you try to load and parse a JSON file with multiple JSON objects in Python, you received an error. json.decoder.JSONDecodeError: Extra data error.

The reason is that the load method can only handle a single JSON object.

The file is invalid if it contains more than one JSON object. When you try to load and parse a JSON file with multiple JSON objects, each line contains valid JSON, but as a whole, it is not a valid JSON as there is no top-level list or object definition. We can call JSON a valid JSON only when there is a top-level list or object definition.

For example, you wanted to read the following JSON file, filter some data, and store it into a new JSON file.

{"id": 1, "name": "Ault", "class": 8, "email": "ault@pynative.com"}
{"id": 2, "name": "john", "class": 8, "email": "jhon@pynative.com"}
{"id": 3, "name": "josh", "class": 8, "email": "josh@pynative.com"}
{"id": 4, "name": "emma", "class": 8, "email": "emma@pynative.com"}

If your file contains a list of JSON objects, and you want to decode one object one-at-a-time, we can do it. To Load and parse a JSON file with multiple JSON objects we need to follow below steps:

• Create an empty list called jsonList
• Read the file line by line because each line contains valid JSON. i.e., read one JSON object at a time.
• Convert each JSON object into Python dict using a json.loads()
• Save this dictionary into a list called result jsonList.

Let’ see the example now.

import json

studentsList = []
print("Started Reading JSON file which contains multiple JSON document")
with open('students.txt') as f:
    for jsonObj in f:
        studentDict = json.loads(jsonObj)
        studentsList.append(studentDict)

print("Printing each JSON Decoded Object")
for student in studentsList:
    print(student["id"], student["name"], student["class"], student["email"])

Output:

Started Reading JSON file which contains multiple JSON document
Printing each JSON Decoded Object
1 Ault 8 ault@pynative.com
2 john 8 jhon@pynative.com
3 josh 8 josh@pynative.com
4 emma 8 emma@pynative.com

Let us know if any comments.