id of a nested serializer is missing

[Tino de Bruijn]

I am using a nested serializer as described here: http://www.django-rest-framework.org/api-guide/relations/#writable-nested-serializers. Creation works fine, but in the update method I cannot get the ids of the related models. The main serializer looks like this:

class StringSerializer(serializers.ModelSerializer):

    panels = PanelSerializer(many=True)

    class Meta:

        model = String

        fields = ('id', 'systeem', 'dak', 'panels')

    def update(self, instance, validated_data):

        panels_data = validated_data.pop('panels')

        old_panel_ids = set(instance.panels.values_list('id', flat=True))

        for attr, value in validated_data.items():

            setattr(instance, attr, value)

        instance.save()

        panels = []

        for panel_data in panels_data:

            if 'id' in panel_data:

                panel = Panel.objects.get(pk=panel_data['id'])

                for attr, value in panel_data.items():

                    setattr(panel, attr, value)

            else:

                panel = Panel.objects.create(string=instance, **panel_data)

            panels.append(panel)

        new_panel_ids = set([p.id for p in panels])

        remove_ids = old_panel_ids - new_panel_ids

        Panel.objects.filter(id__in=remove_ids).delete()
        return instance

and the nested PanelSerializer looks like this:

class PanelSerializer(serializers.ModelSerializer):

    class Meta:

        model = Panel

        fields = ('id', 'orientation', 'angle', 'meting', 'midpoint_coordinates')

The problem is that there never is an 'id' in validated_data['panels'], while it is passed in the json (and is also present in self.data).

How do I get the id's so I can avoid creating new panels every time?

[Xavier Ordoquy]

Hi,

Try to print the serializer to ensure the id isn’t read only.

Regards,

Xavier,

Linovia.

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[Tino de Bruijn]

Yeah, that was the case. Wouldn't expect it to be, but I can see the point.

Thanks,


Tino

Xavier Ordoquy

29 October 2015 at 13:32 via Postbox

Hi,

Try to print the serializer to ensure the id isn’t read only.

Regards,

Xavier,

Linovia.

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Tino de Bruijn

29 October 2015 at 13:16 via Postbox

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