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Python – List of User Defined Objects to JSON String
To convert a Python List, with elements of primitive datatypes, to JSON string, we use json.dumps() function and pass the list as argument to it. But, to convert a list of user defined objects, we use list comprehension with json.dumps().
Syntax
The syntax to use json.dumps() function with list comprehension to convert list list_name of user defined objects to JSON string is
import json
json_string = json.dumps([obj.__dict__ for obj in list_name])
Examples
1. Convert list of Student objects to JSON
In this example, we will take a Python list with objects of type Student, and convert it to JSON string.
Python Program
import json
class Student:
def __init__(self, name, id):
self.name = name
self.id = id
s1 = Student('Jack', 4)
s2 = Student('Sunil', 6)
myList = [s1, s2]
jsonStr = json.dumps([obj.__dict__ for obj in myList])
print(jsonStr)
Run Code CopyOutput
[{"name": "Jack", "id": 4}, {"name": "Sunil", "id": 6}]
Summary
In this Python JSON Tutorial, we learned how to convert a Python List of user-defined objects, into a JSON string.