[Tut] Python TypeError: Object is Not Subscriptable (How to Fix This Stupid Bug)

[Tut] Python TypeError: Object is Not Subscriptable (How to Fix This Stupid Bug) - Printable Version

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[Tut] Python TypeError: Object is Not Subscriptable (How to Fix This Stupid Bug) - xSicKxBot - 11-12-2020

Python TypeError: Object is Not Subscriptable (How to Fix This Stupid Bug)

Do you encounter this stupid error?

[Image: image-20.png]

You’re not alone—thousands of coders like you generate this error in thousands of projects every single month. This short tutorial will show you exactly why this error occurs, how to fix it, and how to never make the same mistake again. So, let’s get started!

Python throws the

Code:
TypeError object is not subscriptable

if you use indexing with the square bracket notation on an object that is not indexable. This is the case if the object doesn’t define the

Code:
__getitem__()

method. You can fix it by removing the indexing call or defining the

Code:
__getitem__

method.

The following code snippet shows the minimal example that leads to the error:

Code:
variable = None
print(variable[0])
# TypeError: 'NoneType' object is not subscriptable

You set the

Code:
variable

to the value

Code:
None

. The value

Code:
None

is not a container object, it doesn’t contain other objects. So, the code really doesn’t make any sense—which result do you expect from the indexing operation?

Exercise: Before I show you how to fix it, try to resolve the error yourself in the following interactive shell:

https://trinket.io/embed/python/e55b915062

If you struggle with indexing in Python, have a look at the following articles on the Finxter blog—especially the third!

Related Articles:

Indexing in Python
Slicing in Python
Highly Recommended: Accessing the Index of Iterables in Python

Note that a similar problem arises if you set the variable to the integer value

Code:
42

instead of the

Code:
None

value. The only difference is that the error message now is

Code:
"TypeError: 'int' object is not subscriptable"

You can fix the non-subscriptable TypeError by wrapping the non-indexable values into a container data type such as a listin Python:

Code:
variable = [None]
print(variable[0])
# None

The output now is the value

Code:
None

and the script doesn’t throw an error anymore.

An alternative is to define the

Code:
__getitem__

method in your code:

Code:
class X: def __getitem__(self, i): return f"Value {i}" variable = X()
print(variable[0])
# Value 0

You overwrite the

Code:
__getitem__

method that takes one (index) argument

Code:
i

(in addition to the obligatory

Code:
self

argument) and returns the

Code:
i

-th value of the “container”. In our case, we just return a string

Code:
"Value 0"

for the element

Code:
variable[0]

and

Code:
"Value 10"

for the element

Code:
variable[10]

. It doesn’t make a lot of sense here but is the minimal example that shows how it works.

I hope you’d be able to fix the bug in your code! Before you go, check out our free Python cheat sheets that’ll teach you the basics in Python in minimal time:

The post Python TypeError: Object is Not Subscriptable (How to Fix This Stupid Bug) first appeared on Finxter.