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

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

The Python "AttributeError: 'NoneType' object has no attribute" occurs when we try to call the group() method on a None value, e.g. after calling match() or search() with no matches. To solve the error, use an if statement before calling group.

Here is a very simple example of how the error occurs.

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example = None

# ⛔️ AttributeError: 'NoneType' object has no attribute 'group'
example.group()

Trying to access or set an attribute on a None value causes the error.

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

For example, the re.match() and re.search methods return None if there are no matches.

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import re

# 👇️ None
m = re.match(r"(\w+) (\w+)", "hello")

# ⛔️ AttributeError: 'NoneType' object has no attribute 'group'
print(m.group())

Since the string does not match the pattern, the match() method returns None.

You can get around this by using an if statement to check if there are matches before calling group().

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import re

m = re.match(r"(\w+) (\w+)", "hello")

if m:
    print(m.group())
else:
    print('There are no matches') # 👉️ this runs

You could also be more explicit in the if statement and check that the m variable is not None.

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import re

m = re.match(r"(\w+) (\w+)", "hello")

if m is not None:
    print(m.group())
else:
    print('There are no matches')

The re.search() method also returns None if no position in the string matches the pattern.

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import re

# 👇️ None
m = re.search('(?<=abc)def', 'xyz')

# ⛔️ AttributeError: 'NoneType' object has no attribute 'group'
print(m.group(0))

You can use the same approach to only call the group method if there was a match.

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import re

m = re.search('(?<=abc)def', 'abcdef')

if m is not None:
    print(m.group())  # 👉️ def
else:
    print('There are no matches')

The if block is only ran if the m variable is not None, otherwise the else block runs.

The same is the case when using the Match.groups method.

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import re

# 👇️ none
m = re.match(r"(\d+)\.(\d+)", "hello")

# ⛔️ AttributeError: 'NoneType' object has no attribute 'groups'
print(m.groups())

The Match.groups method returns None if there are no matches and a default argument is not provided.

To get around the error, use a simple if statement.

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import re

# 👇️ none
m = re.match(r"(\d+)\.(\d+)", "123.456")

if m is not None:
    print(m.groups())  # 👉️ ('123', '456')
else:
    print('There are no matches')

The "AttributeError: 'NoneType' object has no attribute 'group'" 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 certain condition is met.