How to Solve Python TypeError: Object of type Response is not JSON serializable

If you’re working with Python and dealing with APIs, you might encounter the error:

TypeError: Object of type Response is not JSON serializable

This error commonly occurs when attempting to serialize a Response object (typically from libraries like requests or flask) into JSON, which is not directly serializable. In this blog post, we’ll explore why this happens and provide a simple example to help you fix it.

Understanding the Error

The root of the problem lies in how Python’s json module works. The json.dumps() function, for instance, is designed to serialize data structures like dictionaries, lists, strings, and numbers into a JSON format. However, some complex objects (like the Response object) cannot be converted directly.

Let’s break down the error message:

• TypeError: This indicates that Python encountered a mismatch between the data type it expected and what it actually received.
• Object of type Response: The Response object typically comes from libraries such as requests when making HTTP calls.
• is not JSON serializable: This suggests that Python doesn’t know how to turn the Response object into JSON.

Example to Reproduce the Error

Let’s create a simple scenario using the popular requests library to simulate an HTTP request:

import requests
import json

# Send a GET request to a mock API
response = requests.get("https://jsonplaceholder.typicode.com/posts/1")

# Attempt to serialize the response object
json_data = json.dumps(response)

When you run this code, Python will raise the following error:

TypeError: Object of type Response is not JSON serializable

This happens because the response object is not a simple data type like a dictionary or string. Instead, it contains many attributes like status_code, headers, and content—none of which can be directly serialized into JSON.

How to Solve the Error

To fix this error, you need to extract the data from the Response object that can be serialized. In most cases, this means accessing the JSON content of the response (if the response body contains JSON data).

Instead of serializing the Response object itself, you can serialize the JSON content of the response like this:

import requests
import json

# Send a GET request to a mock API
response = requests.get("https://jsonplaceholder.typicode.com/posts/1")

# Extract the JSON content from the response
json_data = response.json()

# Now you can serialize the JSON content
serialized_data = json.dumps(json_data, indent=4)

# Print the serialized JSON
print(serialized_data)

Breakdown of the Fix

• response.json(): This method is a shortcut in the requests library that automatically parses the response body as JSON (assuming the content type is JSON).
• json.dumps(): This method is now working on the parsed JSON data (typically a Python dictionary), which is a format that Python’s json module can serialize without any issues.

Additional Tip: Handling Non-JSON Responses

If you’re unsure whether the response body contains JSON, you can add a check before trying to access it:

import requests

response = requests.get("https://jsonplaceholder.typicode.com/posts/1")

# Check if the response contains JSON
if response.headers['Content-Type'] == 'application/json':
    json_data = response.json()
else:
    print("The response is not JSON")

Output:

The response is not JSON

This ensures that you don’t try to serialize non-JSON content, which would raise another error.

Key Takeaways:

• The error occurs when trying to serialize a Response object directly.
• Use response.json() to access the JSON data and then serialize it.
• Always check the content type of the response to ensure it’s JSON before processing.

By following these steps, you can resolve the Python TypeError and work efficiently with APIs in Python.

Summary

The TypeError: Object of type Response is not JSON serializable occurs when you mistakenly try to serialize a complex object like Response instead of the data it contains. By simply extracting the JSON content from the Response object, you can easily resolve this error and avoid similar issues in the future.

For further reading on errors involving TypeError, go to the articles:

• How to Solve Python TypeError: ‘Response’ object is not subscriptable

To learn more about Python for data science and machine learning, go to the online courses page on Python for the most comprehensive courses available.

Have fun and happy researching!