Attributeerror nonetype object has no attribute append [Solved]

In this article, we will explore different solutions for attributeerror nonetype object has no attribute append error.

Also, we will provide example codes and the causes of this error.

But before that, we will familiarize ourselves first what is AttributeError and NoneType objects.

What is attributeerror nonetype object has no attribute append?

The AttributeError: ‘NoneType’ object has no attribute ‘append’ error occurs when you try to append an item to a NoneType object.

This error is often encountered when working with lists and is caused when you try to append an item to a list that has not been properly initialized.

Causes of attributeerror nonetype object has no attribute append

This error occurs for the following reasons:

1. Using a function where it does not return anything.
2. Calling the append() method on the None value.
3. Assigning a variable to the result of calling a built-in function that doesn’t return anything.
4. Having a function that only returns a value if a certain condition is met.

How to fix attributeerror nonetype object has no attribute append

Here are the following solutions for attributeerror nonetype object has no attribute append error.

Use if-else Condition statement

Every time we call the append() method on None value the attributeerror nonetype object has no attribute append error occurs.

Here is an example code that raises an error:

color_list = None
color_list.append("Red")
print(color_list)

This will output the following:

AttributeError: ‘NoneType’ object has no attribute ‘append’

Apparently, the error occurs when the append() method is utilized in none value.

Note: The append() method is used in Python to append the element at the end of the list. Thus, this method updates the current list, so it does not return any value.

To fix this error try the following code, we will use if-else statement in our program to check the none value of the variable.

color_list = None

if color_list is not None:
    print('variable is NOT None')
    color_list.append('Red')
else:
    print('variable is None')

Output:

variable is None

The code above explains:

• When we utilized the if-else condition along with the combination of is not operator to check if the input variable is “none” or not.
• If the input variable is not equal to none, the statements in the “if” block are executed, and the list’s value is appended using the “append()” function.
• If the variable value is none, the “else” block is executed, and the message “variable is none” is printed to the screen using the “print()” function.

Return Value to Function

The error occurs when a function does not return any value.

Here is the example code:

def mySample():
    print(['red'])
color_value = mySample()

color_value.append('Blue')
print(color_value)

Output:

AttributeError: ‘NoneType’ object has no attribute ‘append’

To fix this error return the value of the function to the main program.

For instance, in the following code, the color value is returned with the use of the return function statement:

    def mySample():
        return (['RED'])
    color_value = mySample()
    
    color_value.append('BLUE')
    print(color_value)

Output:

[‘RED’, ‘BLUE’]

Call the Append Function from the list Containing Value

The “AttributeError” occurs when the “append()” function is called on the return value of these functions.

color_value = ['Red', 'Blue', 'Green']
color_sorted = color_value.sort()

print(color_sorted)
color_sorted.append('Yellow')

Output:

AttributeError: ‘NoneType’ object has no attribute ‘append’

To fix this error, always call the “append()” function on an input function with some value.

In our case, the “sort()” method updates the existing list but returns no value. Always call an “append()” function on the original value to append any value.

color_value = ['Red', 'Blue', 'Green']

print('Before Sorting List: ', color_value)
color_value.sort()
print('\nAfter Sorting List: ', color_value)
color_value.append('Yellow')
print('\nAfter Appending List: ', color_value)

Output:

Before Sorting List: ['Red', 'Blue', 'Green']

After Sorting List: ['Blue', 'Green', 'Red'] 

After Appending List: ['Blue', 'Green', 'Red', 'Yellow']

Conclusion

The AttributeError: ‘NoneType’ object has no attribute ‘append’ error can be frustrating, but it is relatively easy to fix once you understand what is causing it.

By initializing your lists properly and checking if they are None before appending items, you can avoid this error and write better Python code.

We hope that this article has provided you with the information you need to fix this error and continue working with Python.

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