[Solved] Identify the error in this custom serializer field code: class UpperCaseField(serializers.Field): def to_internal_value(self, data): return data.upper() field = UpperCaseField() print(field.... | Django

Django - DRF Advanced Features

Identify the error in this custom serializer field code:

class UpperCaseField(serializers.Field):
    def to_internal_value(self, data):
        return data.upper()

field = UpperCaseField()
print(field.to_internal_value(None))

AField class must inherit from serializers.CharField

Bto_internal_value should return lowercase string

CCalling upper() on None causes an AttributeError

Dto_internal_value method is missing a return statement

Step-by-Step Solution

Solution:

Step 1: Check method call on input
The code calls data.upper() but data is None, which has no upper() method.
Step 2: Identify error type
This causes an AttributeError at runtime.
Final Answer:
Calling upper() on None causes an AttributeError -> Option C
Quick Check:
None.upper() = AttributeError [OK]

Quick Trick: Check input type before calling string methods [OK]

Common Mistakes:

MISTAKES

Assuming None is valid string input
Thinking inheritance must be CharField
Missing return statement (actually present)

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Identify the error in this custom serializer field code:

Step 1: Check method call on input

Step 2: Identify error type

Final Answer:

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