AttributeError: 'NoneType' object has no attribute 'get'

AttributeError: 'NoneType' object has no attribute 'get' #

The Python "AttributeError: 'NoneType' object has no attribute 'get'" occurs when we try to call the get() method on a None value, e.g. assignment from function that doesn't return anything. To solve the error, make sure to only call get() on dict objects.

Here is an example of how the error occurs.

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my_dict = None

# ⛔️ AttributeError: 'NoneType' object has no attribute 'get'
my_dict.get('name')

# ✅ if you need to check if not None before calling get
if my_dict is not None:
    print('variable is NOT None')
    print(my_dict.get('hello'))
else:
    print('variable is None')

Trying to call the get() method on a None value is what causes the error.

The most common source of a None value (other than an explicit assignment) is a function that doesn't return anything.

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# 👇️ this function returns None
def get_dict():
    print({'name': 'Alice', 'age': 30})


# 👇️ None
my_dict = get_dict()

# ⛔️ AttributeError: 'NoneType' object has no attribute 'get'
my_dict.get('name')

Notice that our get_dict function doesn't explicitly return a value, so it implicitly returns None.

The "AttributeError: 'NoneType' object has no attribute 'get'" occurs for multiple reasons:

1. Having a function that doesn't return anything (returns None implicitly).
2. Explicitly setting a variable to None.
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.

Some built-in methods mutate a data structure in place and don't return a value. In other words, they implicitly return None.

Make sure you aren't assigning the result of calling a method that returns None to a variable.

If a variable might sometimes store a dict and sometimes store None, you can explicitly check if the variable is not None before you call get().

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my_dict = {'name': 'Alice', 'age': 30}

if my_dict is not None:
    print('variable is NOT None')
    print(my_dict.get('name'))  # 👉️ "Alice"
else:
    print('variable is None')

The if block will run only if the my_dict variable does not store a None value, otherwise the else block runs.

Another common cause of the error is having a function that returns a value only if a condition is met.

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def get_dict(a):
    if len(a) > 1:
        return a


my_dict = get_dict({'name': 'Alice'})

print(my_dict)  # 👉️ None

The if statement in the get_dict function is only run if the passed in dictionary has a length greater than 1.

To solve the error in this scenario, you either have to check if the function didn't return None or return a default value if the condition is not met.

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def get_dict(a):
    if len(a) > 1:
        return a
    return {}


my_dict = get_dict({'name': 'Alice'})

print(my_dict)  # 👉️ {}

Now the function is guaranteed to return a dict regardless if the condition is met.

Conclusion #

The Python "AttributeError: 'NoneType' object has no attribute 'get'" occurs when we try to call the get() method on a None value, e.g. assignment from function that doesn't return anything. To solve the error, make sure to only call get() on dict objects.