If you are looking for a solution to the error AttributeError: ‘NoneType’ object has no attribute ‘append’, here are the causes of the error and some ways you can use it to fix it. Details are below.
What causes the AttributeError: ‘NoneType’ object has no attribute ‘append’ in Python?
AttributeError is one of the exceptions in Python. AttributeError occurs when you access an undefined attribute on an object.
The error happens because you call the append() method on the value None.
Example:
valueList = None
# The append() method adds an element to the end of the list
valueList.append('learnshareit')
print(valueList)Output:
Traceback (most recent call last):
File "./prog.py", line 4, in <module>
AttributeError: 'NoneType' object has no attribute 'append'The same error occurs when you initialize a function that returns None.
Example:
def NoneFunc():
return None
noneFunction = NoneFunc()
noneFunction.append('Learnshareit')
print(noneFunction)Output:
Traceback (most recent call last):
File "./prog.py", line 5, in <module>
AttributeError: 'NoneType' object has no attribute 'append'Even if you declare a function that returns no value gives the same error.
Example:
def noValueFunc():
print(['visit'])
noValue = noValueFunc()
noValue.append('Learnshareit')
print(noValue)Output:
Traceback (most recent call last):
File "./prog.py", line 5, in <module>
AttributeError: 'NoneType' object has no attribute 'append'How to solve the AttributeError: ‘NoneType’ object has no attribute ‘append’ in Python?
Check the NoneType object.
You can use the Authentication operator to check if a variable can validly call append().
Example:
- Declare a variable whose value is None.
- Use the Authentication operator. If the variable contains the value None, execute the if statement otherwise, the variable can use the append() attribute because it does not contain the value None.
- You can replace the ‘is’ operator with the ‘is not’ operator (substitute statements accordingly).
valueList = []
# Use the 'is' operator
if valueList is None:
print('Object is None')
else:
print('Object is not None')
valueList.append('learnshareit')
print(valueList)Output:
Object is not None
['learnshareit']You can use the relational operator ‘!=’ for error handling.
The ‘!=’ operator compares the values of the arguments: if they are different, it returns True. If equal, returns False.
Example:
valueList = []
# Use the relational operator '!='
if valueList != None:
print('Object is not None')
valueList.append('learnshareit')
else:
print('Object is None')
print(valueList)Output:
Object is not None
['learnshareit']Use the try/except block check for the occurrence of None.
Example:
valueList = []
try:
valueList.append('learnshareit')
except AttributeError:
print('Object is None')
print(valueList)Output:
['learnshareit']Avoid initializing functions that do not return results or return None.
To solve the error in this case, you need to change the function’s return value (see the two examples that cause the above error) to a list that can be an empty list or a list with elements already present.
Example:
def ValueFunc():
# The return value is an empty list. This will not cause an error
return []
myValue = ValueFunc()
# Add the element to that list
myValue.append('Learnshareit')
print(myValue)Output:
['learnshareit']Summary
The problem AttributeError: ‘NoneType’ object has no attribute ‘append’ in Python is probably solved. If there is a point that does not make sense or you have a better approach, please share it with everyone in the comments box below.
Maybe you are interested:
- AttributeError: dict_keys object has no attribute ‘remove’
- AttributeError: ‘list’ object has no attribute ‘lower’
- AttributeError: ‘list’ object has no attribute ‘len’
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
