This article will give you some solutions to fix the NameError: name ‘null’ is not defined in Python. Follow it and solve your problem.
What causes the NameError: name ‘null’ is not defined in Python?
The keyword ‘null’ is used in many programming languages today to represent that the pointer is not pointing to any value. NULL is equivalent to 0. A newly created pointer points “miscellaneous” to a particular memory area. Assign the pointer to NULL to make sure it points to 0. Even though 0 is an invalid location, it’s easier to manage than when the pointer points to an area we don’t know. But in Python, ‘null’ is replaced by ‘None’.
‘None’ is a specific object indicating that the object is missing the presence of a value. The Python Null object is the singleton None.
In other words, ‘None’ in Python is similar to the ‘Null’ keyword in other programming languages.
‘NameError’ is an error when you use a variable, function, or module that is not declared or you are not using it properly.
“NameError: name ‘null’ is not defined” error happens because ‘null’ is not in Python.
Example:
myDic = {"Name": 1, "Age": 2 , "Asset": null , "Vacations": 3}
print(myDic['Asset'])Output:
Traceback (most recent call last):
File "./prog.py", line 1, in <module>
NameError: name 'null' is not definedHow to solve this error?
Use the json.loads() method
You can use the json.loads() function to solve this problem.
The json.loads() function can convert a JSON string into a dictionary in Python.
Example:
- Import json module.
- Declare a JSON string.
- Use json.loads() function to convert JSON format to a dict.
import json
# Declare a JSON string
myJsonStr = '{"Name": "" , "Age": "" , "Asset": null , "Vacations": "Developer"}'
# Use json.loads() function to convert Json format to a dict
myDic = json.loads(myJsonStr)
print(myDic)
print(type(myDic))Output:
{'Name': '', 'Age': '', 'Asset': None, 'Vacations': 'Developer'}
<class 'dict'>In the above example, you can see that after using json.loads() function ‘null’ has changed to ‘None’.
Replace ‘null’ with ‘None’ in the dictionary
As I stated in the cause in Python, there is no ‘null’. To fix the error, all you need to do is to replace it with ‘None’.
Example:
- Declare a dictionary containing a null value.
- Replace ‘null’ with ‘None’.
# Replace 'null' with 'None'
myDic = {"Name": "" , "Age": "" , "Asset": None , "Vacations": "Developer"}
print(myDic['Asset'])Output:
NoneUse the json.dumps() method
You also can use the json.dumps() function to solve this problem.
Example:
- Import JSON module.
- Declare a JSON string.
- The json.dumps() function converts a Python object to a JSON string.
import json
# Declare a JSON string
myJsonStr = '{"Name":"" ,"Age":"" , "Asset":null ,"Vacations":"Developer"}'
# Use json.dumps() function
resultStr = json.dumps(myJsonStr)
print(resultStr)
print(type(resultStr))Output:
"{\"Name\":\"\" ,\"Age\":\"\" , \"Asset\":null ,\"Vacations\":\"Developer\"}"
<class 'str'>After using the json.dumps() function, the Python object converts to a JSON string.
Summary
Here are the methods to help you solve the NameError: name ‘null’ is not defined in Python. If you have any questions about this issue, leave a comment below. I will answer your questions. Thank you for reading!
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My name is Jason Wilson, you can call me Jason. My major is information technology, and I am proficient in C++, Python, and Java. I hope my writings are useful to you while you study programming languages.
Name of the university: HHAU
Major: IT
Programming Languages: C++, Python, Java