JsonField source and validate(self, attrs) might have a mismatch

[kxtells]

Hello everyone.

I have a situation that seemed strange at first and thought to ask if it is intended behaviour or something unexpected for 3.15.1.

In this code example I provide the smallest example I could come up with that creates this situation.

In this case I have a Comment class, that I serialize via a CommentSerializer that declares a specific source function to fill up the given field.

Alongside this we have some specific validate(self, data) for this serializer.

I would expect the validation payload to come as

{'content': 'aha'}

But instead it comes as

{'myFunc': 'aha'}

I imagine that if the source points to an attribute this behaviour would not be too bad, but when pointing to a function it seems strange to me.

As said, I'm just wondering if this is intended or it's some unexpected behaviour.

from rest_framework import serializers

class Comment():
    def __init__(self, txt):
        self.content = txt

    def myFunc(self):
        return "POTATO"

class CommentSerializer(serializers.Serializer):
    content = serializers.CharField(max_length=200, source="myFunc")

    def validate(self, data):
        print(data)
        return data

comment = Comment("HelloDear")
serializer = CommentSerializer(data={"content": "aha"})
print(serializer.is_valid())

Salut, and thanks for the hard work!

[sevdog]

For what I know this is a behaviour which has been in DRF for long time.

Maybe it is not well documented, the source attribute of fields works in both read and in write operations. The meaning of this is to have an "internal" name (the source) and an "external" name (field name) for the same field, in this way you may change your internal data structure without having the API users to change too.