ModelSerializer fields with source parameter no longer work (regression in 3.5)

[dariusmazeika]

django-money/djmoney/contrib/django_rest_framework/fields.py

Line 73 in 408ab21

field = model_meta.get_field(self.field_name)

Seems to be introduced with #722.

django - 5.0.3
drf - 3.14.0
djmoney - 3.5.1
python - 3.11

ModelSerializer with MoneyField which has source passed in fails to resolve field_name from source

  File "/usr/local/lib/python3.11/site-packages/rest_framework/serializers.py", line 227, in is_valid
    self._validated_data = self.run_validation(self.initial_data)
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/rest_framework/serializers.py", line 426, in run_validation
    value = self.to_internal_value(data)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/rest_framework/serializers.py", line 481, in to_internal_value
    primitive_value = field.get_value(data)
                      ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/djmoney/contrib/django_rest_framework/fields.py", line 43, in get_value
    field = model_meta.get_field(self.field_name)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/site-packages/django/db/models/options.py", line 683, in get_field
    raise FieldDoesNotExist(
django.core.exceptions.FieldDoesNotExist: Item has no field named 'price_amount'

Can be reproduced with following model and serializer:

class Item(models.Model):
    price = MoneyField(max_digits=16)

class ItemModelSerializer(serializers.ModelSerializer):
    price_amount = MoneyField(source="price",
        max_digits=16,
        decimal_places=2,
    )

    class Meta:
        model = Item
        fields = ["price_amount", "price_amount_currency"]

[dariusmazeika]

I have a simple fix with test, just not sure how to contribute, probably need permission.
Line in question should be:
field = model_meta.get_field(self.source)

[benjaoming]

@dariusmazeika that looks like a good fix! There are already quite a bit of test cases, and with your addition, one could hope that it's getting closer to an exhaustive pattern.

If you fork the repository and open a PR, that's sufficient. There are some notes in the README about how to run tests locally.

[dariusmazeika]

@benjaoming done. I placed the test under same test case that was introduced with #722 as I guess it's related, hope that's all good :)