TypeError: Object of type function is not JSON serializable

Introduction: TypeError: Object of type function is not JSON serializable

The Python “TypeError: Object of type function is not JSON serializable” occurs when we try to serialize a function to JSON. This error can be caused by a number of reasons, but the most common cause is when we forget to call the function before passing it to the json.dumps() method.

Understanding the Error “TypeError: Object of type function is not JSON serializable”

Here is an example of how the error occurs:

import json

def get_employee():
    return {'name': 'Alice', 'age': 30}

json_str = json.dumps(get_employee) # forgot to call function

We forgot to call the get_employee() function in the call to the json.dumps() method, which results in the TypeError: Object of type function is not JSON serializable.

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Solution: TypeError: Object of type function is not JSON serializable

The solution to this error is quite simple, we just need to make sure to call the function and serialize the object that the function returns. Here is an example of how to fix the error:

import json

def get_employee():
    return {'name': 'Alice', 'age': 30}

json_str = json.dumps(get_employee())
print(json_str)  # '{"name": "Alice", "age": 30}'
print(type(json_str))  # <class 'str'>

We called the function, so we serialized the dict object rather than trying to serialize the function itself.

Other serialization issues:

It’s important to note that the JSONEncoder class supports the following objects and types by default:

PythonJSON
dictobject
list, tuplearray
strstring
int, float, int and float derived Enumsnumber
Truetrue
Falsefalse
Nonenull

It’s also worth noting that JSONEncoder class doesn’t support function to JSON conversion by default.

Conclusion on TypeError: Object of type function is not JSON serializable

The Python “TypeError: Object of type function is not JSON serializable” occurs when we try to serialize a function to JSON. To solve the error, make sure to call the function and serialize the object that the function returns.

This will ensure that you’re serializing the correct object and that the JSONEncoder class can properly handle it. Additionally, if you are getting this error while trying to serialize other object types like ‘object of type response‘ or ‘object of type user‘ in flask, then you have to make sure that you are returning the correct object that is serializable.

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