[Solved] Python serialization error: NameError: name ‘JSON’ is not defined: Best Guide in 2024

[Solved] Python serialization error: NameError: name ‘JSON’ is not defined: Best Guide in 2024

Author: Amresh Mishra | Published On: February 21, 2024

Error content:

NameError: name ‘json’ is not defined

Prompt: JSON is not defined;

JSON used in serialization:

        rep = requests.post(url, data=json.dumps(data))

‘JSON’ is not defined Solution:

The error is generated due to not presence of JSON.

 JSON is a python library. To overcome this, you need to import JSON. You can import JSON directly.

import json

Also, read | [Solved] Networkx Error: Attributeerror: ‘graph’ object has no attribute ‘node’

Ah, the joys of programming! Nothing beats the thrill of seeing your code run flawlessly, right? Well, that is until you hit a wall, specifically a Python serialization error: NameError: name ‘JSON’ is not defined. If you’ve stumbled upon this error, don’t worry. You’re not alone, and more importantly, there’s a solution. Let’s dive into this pesky error and figure out how to squash it.

Python serialization error: NameError: name ‘JSON’ is not defined

What is Serialization in Python?

Before we tackle the error, let’s first understand what serialization is. In Python, serialization refers to the process of converting a Python object into a format that can be easily stored or transmitted, and then later reconstructed. Common formats include JSON, XML, and pickle.

JSON (JavaScript Object Notation) is a popular data format used for exchanging data between a server and a client. It’s easy to read and write for humans and easy to parse and generate for machines.

So, why would you serialize data? Here are a few reasons:

  1. Data Persistence: Save complex data structures to a file and load them later.
  2. Data Transfer: Send data over a network.
  3. Caching: Store the state of an object to reload it quickly without reprocessing.

A Simple Example

import json

data = {
    "name": "John",
    "age": 30,
    "city": "New York"

# Serialize
json_string = json.dumps(data)

# Deserialize
data_back = json.loads(json_string)

The Infamous Error: NameError: name ‘JSON’ is not defined

So, you’re all set, you write your code, and then… BAM! You get the NameError: name ‘JSON’ is not defined error. What gives?

The Culprit

The problem is actually quite simple: Python is case-sensitive. Yes, the language that gives you so much power and flexibility also demands respect to capitalization. The module you need is json (all lowercase), but your code is likely trying to use JSON (uppercase).

Here’s a typical scenario:

data = {
    "name": "Jane",
    "age": 25,
    "city": "San Francisco"

json_string = JSON.dumps(data)  # This will cause the error

The Fix

The fix is delightfully simple. Just change JSON to json.

import json

data = {
    "name": "Jane",
    "age": 25,
    "city": "San Francisco"

json_string = json.dumps(data)  # This will work just fine

Common Pitfalls and How to Avoid Them

  1. Forgetting to Import the Module

It’s easy to forget to import the module, especially if you’re in the zone and cranking out code at lightning speed.

data = {"key": "value"}
json_string = json.dumps(data)  # NameError: name 'json' is not defined

Solution: Always import the module at the beginning of your script.

import json

data = {"key": "value"}
json_string = json.dumps(data)
  1. Using the Wrong Case

Remember, Python cares about case.

import JSON  # ImportError: No module named 'JSON'

Solution: Use the correct case.

import json
  1. Misspelling the Module Name

It happens to the best of us. You might accidentally type jsn instead of json.

import jsn  # ImportError: No module named 'jsn'

Solution: Double-check your spelling.

import json

FAQs About Python serialization error: NameError

Q: What is JSON?

A: JSON stands for JavaScript Object Notation. It’s a lightweight data interchange format that’s easy for humans to read and write and easy for machines to parse and generate.

Q: Why do I need to import json in Python?

A: You need to import the json module in Python to work with JSON data. The json module provides methods for serializing and deserializing data.

Q: Can I use pickle instead of json?

A: Yes, you can use pickle for serialization, but it is specific to Python and not human-readable. JSON is more versatile for data exchange between different systems.

Q: How do I fix the NameError: name 'JSON' is not defined error?

A: Ensure that you import the json module and use json (lowercase) instead of JSON (uppercase).

Getting Fancy with JSON Serialization

Now that we’ve covered the basics, let’s explore some more advanced topics in JSON serialization.

1. Custom Serialization: Python serialization error: NameError

Sometimes, the default JSON encoder can’t handle your custom objects. For instance, if you have a datetime object, you’ll need to provide a way to serialize it.

import json
from datetime import datetime

class CustomEncoder(json.JSONEncoder):
    def default(self, obj):
        if isinstance(obj, datetime):
            return obj.isoformat()
        return super().default(obj)

data = {
    "name": "John",
    "birthdate": datetime.now()

json_string = json.dumps(data, cls=CustomEncoder)

2. Custom Deserialization: Python serialization error: NameError

Similarly, you might need to handle custom deserialization.

import json
from datetime import datetime

def custom_decoder(dct):
    if 'birthdate' in dct:
        dct['birthdate'] = datetime.fromisoformat(dct['birthdate'])
    return dct

json_string = '{"name": "John", "birthdate": "2023-01-01T12:34:56"}'
data = json.loads(json_string, object_hook=custom_decoder)

3. Pretty Printing: Python serialization error: NameError

Sometimes, you want your JSON to be more readable. Pretty printing to the rescue!

import json

data = {
    "name": "John",
    "age": 30,
    "city": "New York"

json_string = json.dumps(data, indent=4)

When Things Go Wrong

Despite your best efforts, things can still go wrong. Here are some common issues and how to fix them.

1. Non-serializable Objects: Python serialization error: NameError

If you try to serialize an object that isn’t serializable, you’ll get a TypeError.

import json

class MyClass:

data = MyClass()

json_string = json.dumps(data)  # TypeError: Object of type MyClass is not JSON serializable

Solution: Implement custom serialization logic.

import json

class MyClass:
    def __init__(self, name):
        self.name = name

    def to_json(self):
        return {"name": self.name}

data = MyClass("John")
json_string = json.dumps(data.to_json())

2. Incorrect Data Formats: Python serialization error: NameError

Sometimes, the data you’re working with isn’t in the correct format.

import json

data = "{name: 'John'}"  # This is not valid JSON
json_string = json.loads(data)  # JSONDecodeError: Expecting property name enclosed in double quotes

Solution: Ensure your data is in the correct format.

import json

data = '{"name": "John"}'  # This is valid JSON
json_string = json.loads(data)

3. Circular References

If your data structure contains circular references, you’ll run into issues.

import json

a = {}
b = {"a": a}
a["b"] = b

json_string = json.dumps(a)  # TypeError: Circular reference detected

Solution: Avoid circular references or implement custom serialization.

import json

a = {}
b = {"a": a}
a["b"] = "circular reference"

json_string = json.dumps(a)

Humor Break: A Tale of Two Programmers

Once upon a time in a land of code, there were two programmers, Alice and Bob. Alice was meticulous and always double-checked her imports and capitalization. Bob, on the other hand, was a bit more… let’s say, _relaxed. One day, Bob wrote a script that used JSON serialization. He ran his code and was immediately greeted with the dreaded NameError: name 'JSON' is not defined error._

Bob: “What is this madness?!”

Alice: “Did you import the json module?”

Bob: “Of course I did… wait, let me check.”

It turned out Bob had indeed forgotten to import the module.

Alice: “See? Easy fix. Also, remember to use lowercase ‘json’ not ‘JSON’.”

Bob: “Oh, the tyranny of case sensitivity!”

And so, Bob learned the importance of importing modules and respecting case sensitivity, and they both coded happily ever after.

Real-world Applications

Serialization isn’t just a theoretical concept; it’s used in many real-world applications.

1. Web Development

In web development, JSON is used extensively for data interchange. When building APIs, you’ll often serialize data to JSON to send it to the client.

from flask import Flask, jsonify

app = Flask(__name__)

def user():
    data = {"name": "John",

 "age": 30, "city": "New York"}
    return jsonify(data)

if __name__ == '__main__':

2. Configuration Files

JSON is a popular format for configuration files due to its simplicity and readability.

import json

config = {
    "host": "localhost",
    "port": 8080,
    "debug": True

with open('config.json', 'w') as config_file:
    json.dump(config, config_file)

with open('config.json', 'r') as config_file:
    config = json.load(config_file)

3. Data Storage and Retrieval

You can use JSON to store and retrieve data, especially for small to medium-sized datasets.

import json

data = {
    "users": [
        {"name": "John", "age": 30},
        {"name": "Jane", "age": 25}

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

with open('data.json', 'r') as file:
    data = json.load(file)

Conclusion on Python serialization error: NameError

The NameError: name 'JSON' is not defined error is a common but easily fixable issue in Python programming. By remembering to import the json module and using the correct case, you can avoid this error and enjoy the benefits of JSON serialization in your projects.

So, next time you’re faced with this error, don’t panic. Take a deep breath, check your imports and capitalization, and you’ll be back on track in no time.

Meta Description

Learn how to solve the common Python serialization error NameError: name 'JSON' is not defined. This article covers the basics of serialization, common pitfalls, advanced techniques, and real-world applications. Perfect for beginner to intermediate Python programmers.

Author: Amresh Mishra
Amresh Mishra is a passionate coder and technology enthusiast dedicated to exploring the vast world of programming. With a keen interest in web development, software engineering, and emerging technologies, Amresh is on a mission to share his knowledge and experience with fellow enthusiasts through his website, CodersCanteen.com.

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