ModelSerializer using model property

as @Robert Townley's comment, this work with version 3.8.2:

class MyModelSerializer(serializers.ModelSerializer):
    ext_link = serializers.ReadOnlyField()

    class Meta:
        model = MyModel
        fields = "__all__"

Because it's not a model field, it needs to be added explicitly to the serializer class

class MyModelSerializer(serializers.ModelSerializer):
    ext_link = serializers.Field()

    class Meta:
        model = MyModel
        fields = ('name', 'ext_link')

The accepted answer doesn't seem to work for me, nor does the ReadOnlyField.

However, I have had success when I use a field that corresponds to the return type of my property function.

So for the example, I would do this:

class MyModelSerializer(serializers.ModelSerializer):
    ext_link = serializers.CharField()

    class Meta:
        model = MyModel
        fields = ('name', 'ext_link')

I've been able to do this with ListField, DictField, and IntegerField as well.