The Python TypeError: NoneType Object Is Not Iterable
is an exception that occurs when trying to iterate over a None
value. Since in Python, only objects with a value can be iterated over, iterating over a None
object raises the TypeError: NoneType Object Is Not Iterable
exception.
What Causes TypeError: NoneType Object Is Not Iterable
For an object to be iterable in Python, it must contain a value. Therefore, trying to iterate over a None
value raises the Python TypeError: NoneType Object Is Not Iterable
exception. Some of the most common sources of None
values are:
- Calling a function that does not return anything.
- Calling a function that sets the value of the data to
None
. - Setting a variable to
None
explicitly.
Python TypeError: NoneType Object Is Not Iterable Example
Here’s an example of a Python TypeError: NoneType Object Is Not Iterable
thrown when trying iterate over a None
value:
mylist = None
for x in mylist:
print(x)
In the above example, mylist
is attempted to be added to be iterated over. Since the value of mylist
is None
, iterating over it raises a TypeError: NoneType Object Is Not Iterable
:
Traceback (most recent call last):
File "test.py", line 3, in <module>
for x in mylist:
TypeError: 'NoneType' object is not iterable
How to Fix TypeError in Python: NoneType Object Is Not Iterable
The Python TypeError: NoneType Object Is Not Iterable
error can be avoided by checking if a value is None
or not before iterating over it. This can help ensure that only objects that have a value are iterated over, which avoids the error.
Using the above approach, a check can be added to the earlier example:
mylist = None
if mylist is not None:
for x in mylist:
print(x)
Here, a check is performed to ensure that mylist
is not None
before it is iterated over, which helps avoid the error.
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