Django REST framework reverse relationship object instance - django

Question

Let's say that we have models like below
class Movie(models.Model):
"""Stores a single movie entry."""
title = models.CharField(max_length=200, blank=False)
class Watchlist(models.Model):
"""Stores a user watchlist."""
user = models.ForeignKey(settings.AUTH_USER_MODEL,
related_name='watchlist',
on_delete=models.CASCADE)
movie = models.ForeignKey(Movie, related_name='watchlist',
on_delete=models.CASCADE)
added = models.BooleanField(default=False)
Serializer
class CustomUserSerializer(serializers.HyperlinkedModelSerializer):
"""Serializer for a custom user model with related user action."""
url = serializers.HyperlinkedIdentityField(
view_name='customuser-detail', lookup_field='username')
watchlist = serializers.HyperlinkedRelatedField(
many=True, view_name='watchlist-detail', read_only=True)
class Meta:
model = CustomUser
fields = ('url', 'username', 'watchlist')
and the view:
class CustomUserViewSet(viewsets.ReadOnlyModelViewSet):
"""
list:
Return a list of all the existing users.
retrieve:
Return the given user with user's watchlist.
"""
queryset = CustomUser.objects.all()
permissions = (IsAdminOrReadOnly)
lookup_field = 'username'
serializer_class = CustomUserSerializer
That all will give us a user and hyperlinked filed to the particular watchlist.
{
"url": "http://127.0.0.1:8000/api/v1/users/John/",
"username": "John",
"favorites": [
"http://127.0.0.1:8000/api/v1/watchlist/2/",
"http://127.0.0.1:8000/api/v1/watchlist/1/"
]
},
but instead of that I would like to get a particular movie instance like that.
{
"url": "http://127.0.0.1:8000/api/v1/users/John/",
"username": "John",
"favorites": [
"http://127.0.0.1:8000/api/v1/movies/33/",
"http://127.0.0.1:8000/api/v1/movies/12/"
]
},
so my question is how can I achieve that? I tried with hyperlinkedrelatedfield but nothing seems to work as expected.

Answer 1

You could use the SerializerMethodField along with reverse.
from rest_framework.reverse import reverse
class CustomUserSerializer(serializers.HyperlinkedModelSerializer):
"""Serializer for a custom user model with related user action."""
url = serializers.HyperlinkedIdentityField(
view_name='customuser-detail', lookup_field='username')
favorites = serializers.SerializerMethodField()
def get_favorites(self, obj):
movie_urls = [
reverse("movie-view", args=[watchlist.movie.id], request=self.context['request'])
for watchlist in obj.watchlist.all()
]
return movie_urls
class Meta:
model = CustomUser
fields = ('url', 'username', 'favorites')