James Lin James Lin - 1 month ago 21
Python Question

Django REST Framework serializer field required=false

from the documentation:


read_only
Set this to True to ensure that the field is used when serializing a representation, but is not used when updating an instance during deserialization.

Defaults to False

required
Normally an error will be raised if a field is not supplied during deserialization. Set to false if this field is not required to be present during deserialization.

Defaults to True.


So I have a model which has a field that's not nullable but I want it to be populated in the pre_save method, so I have set the field to
required=False
in serializer, but doesn't seem to work. I am still getting error when saving the record.

class FavoriteListSerializer(serializers.ModelSerializer):
owner = serializers.IntegerField(required=False)
class Meta:
model = models.FavoriteList


Update:
I have added
serializer_class = serializers.FavoriteListSerializer
to the ViewSet, now instead of getting
This field is required
, which I think got past the validation but then I am getting
This field cannot be null.
I have checked the pre_save method is not being executed, any ideas?

Answer

Yeah, I ran into this issue at some point as well. You need to also update the validation exclusions.

class FavoriteListSerializer(serializers.ModelSerializer):
    owner = serializers.IntegerField(required=False)
    class Meta:
        model = models.FavoriteList

    def get_validation_exclusions(self):
        exclusions = super(FavoriteListSerializer, self).get_validation_exclusions()
        return exclusions + ['owner']
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