Adding a url field linking to an action in serializer in DRF - django

Question

I am using django rest framework. I want to include the url of an action defined in a view in its serializer.
My serializers.py:
from rest_framework import serializers
class CommentSerializer(serializers.ModelSerializer):
"""Serializer for comments."""
class Meta:
model = Comment
fields = ["id", "item", "author", "content", "date_commented", "parent"]
class ItemDetailSerializer(serializers.ModelSerializer):
"""Serializer for items (for retrieving/detail purpose)."""
category = CategorySerializer(many=True, read_only=True)
media = MediaSerializer(many=True, read_only=True)
brand = BrandSerializer(many=False, read_only=True)
specifications = serializers.SerializerMethodField(source="get_specifications")
comments = ??????????????????????????????????????????????????
class Meta:
model = Item
fields = [
"id",
"slug",
"name",
"description",
"brand",
"show_price",
"location",
"specifications",
"is_visible",
"is_blocked",
"created_at",
"updated_at",
"seller",
"category",
"media",
"comments",
"users_wishlist",
"reported_by",
]
read_only = True
editable = False
lookup_field = "slug"
def get_specifications(self, obj):
return ItemSpecificationSerializer(obj.item_specification.all(), many=True).data
My views.py:
from rest_framework import viewsets, mixins, status
from ramrobazar.inventory.models import Item, Comment
from ramrobazar.drf.serializers ItemSerializer, ItemDetailSerializer, CommentSerializer
from rest_framework.permissions import IsAuthenticatedOrReadOnly
from rest_framework.filters import SearchFilter
from django_filters.rest_framework import DjangoFilterBackend
class ItemList(viewsets.GenericViewSet, mixins.ListModelMixin):
"""View for listing and retrieving all items for sale."""
queryset = Item.objects.all()
serializer_class = ItemSerializer
serializer_action_classes = {
"retrieve": ItemDetailSerializer,
}
permission_classes = [IsAuthenticatedOrReadOnly]
lookup_field = "slug"
filter_backends = [DjangoFilterBackend, SearchFilter]
filterset_fields = [
"category__slug",
"brand__name",
]
search_fields = ["name", "description", "category__name", "brand__name", "location"]
def get_serializer_class(self):
try:
return self.serializer_action_classes[self.action]
except:
return self.serializer_class
def retrieve(self, request, slug=None):
item = self.get_object()
serializer = self.get_serializer(item)
return Response(serializer.data)
#action(detail=True, methods=['GET'])
def comments(self, request, slug=None):
item = Item.objects.get(slug=slug)
queryset = Comment.objects.filter(item=item)
serializer = CommentSerializer(queryset, many=True)
return Response(serializer.data, status=status.HTTP_200_OK)
I have an action named comments in the ItemList view which gives all the comments of a specific item. I can get the details of the item from the url /api/items/<slug>. I can get all the comments of the item from the url api/items/<slug>/comments. I want to include a comments field in the ItemDetailSerializer serializer which is a link to api/items/<slug>/commments. How can I accomplish this?

Answer 1

You can do this via SerializerMethodField and reverse:
class ItemDetailSerializer(serializers.ModelSerializer):
...
comments = serializers.SerializerMethodField(source="get_comments")
...
def get_comments(self, obj):
return reverse(YOUR_URL_NAME, kwargs={'slug': obj.slug})

Answer 2

try this:
class ItemDetailSerializer(serializers.ModelSerializer):
...
comments = serializers.CharField(max_length=100, required=False)
def create(self, validated_data):
validated_data['comments'] = self.context['request'].build_absolute_uri() + 'comments'
return super(ContentGalleryListSerializer, self).create(validated_data)

Answer 3

You can use the HyperlinkedIdentityField for this:
comments = serializers.HyperlinkedIdentityField(
view_name='item-comments',
lookup_field='slug'
)
This will then render a comments field that contains a URL to the item-comments view, with the slug as lookup parameter.
You will need to register the view with the name item-comments, for example with:
urlpatterns = [
path('items/<slug>/comments/', ItemList.as_view({'get': 'comments'}), name='item-comments')
]
Note that normally nested routes are discouraged, and you'd put the comments in a separate view. But the above should work.