Expandable Hyperlinked Related FIelds

serializers.py

from rest_framework import serializers


class ExpandableHyperlinkedRelatedField(serializers.HyperlinkedRelatedField):
    """
    Field that returns a link to the related object by default, or the whole object document if the field name
    is provided in the comma separated argument `expand_fields`.
    """
    def __init__(self, *args, **kwargs):
        self.expand_serializer = kwargs.pop('serializer')
        return super(ExpandableHyperlinkedRelatedField, self).__init__(*args, **kwargs)

    def to_representation(self, obj):
        request = self.context.get('request')
        expand_fields = request.query_params.get('expand_fields', '').split(',') if request is not None else []

        if self.field_name not in expand_fields:
            return super(ExpandableHyperlinkedRelatedField, self).to_representation(obj)

        expand_obj = self.queryset.get(pk=obj.pk)

        

# In the NotificationSerializer, we set the 'event' as an expandable hyperlink.
# This means that if the argument `expand_fields=event is provided, we return
# the event document instead of the url.
# This works both in details and list resources.
# Additional changes required if you want to use it on writable fields.
        
class NotificationSerializer(APIV2ModelSerializer):
    event = ExpandableHyperlinkedRelatedField(queryset=models.Event.objects.all(),
                                              view_name='alerting-event-detail',
                                              serializer=EventSerializer)  # Add the serializer argument to the HyperlinkedRelatedField constructor

    definition = serializers.HyperlinkedRelatedField(queryset=models.Definition.objects.all(),
                                                     view_name='alerting-definition-detail')

    class Meta:
        model = models.Notification
        fields = '__all__'