DRF serializer get liked data with post by request user - django

Question

I'm making a social app like facebook.
when getting post(at news feed) data I would like to get Boolean if I pressed like about that post.
models.py
from django.db import models
from django.contrib.auth.models import User
# Create your models here.
class Post(models.Model):
uploader = models.ForeignKey(User)
likes = models.IntegerField(default=0)
point = models.IntegerField(default=0)
isPointReceived = models.BooleanField(default=False)
content = models.TextField()
uploadedTime = models.DateTimeField(auto_now=True)
# editedTime = models.DateTimeField()
def __str__(self):
return ("[uploader = " + self.uploader.username + "]") + (", [id = " + (str)(self.id) + "]") + ("[content = " + self.content[:50] + "]")
class PostLike(models.Model):
post = models.ForeignKey(Post, related_name='postLikes')
liker = models.ForeignKey(User)
def __str__(self):
return "Like" + "| [Post = " + (str)(self.post) + "]" + ", [Liker = " + self.liker.username + "]"
serializers.py
class PostLikeSerializer(serializers.ModelSerializer):
class Meta:
model = PostLike
fields = '__all__'
class PostListSerializer(serializers.ModelSerializer):
uploader = UserDetailSerializer()
isMine = serializers.SerializerMethodField()
isLiked = serializers.SerializerMethodField()
postComments = PostCommentSerializer(many=True, allow_null=True)
class Meta:
model = Post
fields = ('uploader', 'id', 'likes', 'point', 'isPointReceived', 'content', 'uploadedTime', 'postComments', 'isMine', 'isLiked',)
def get_isMine(self, obj):
requestUser = CurrentUserDefault()
return obj.objects.fileter(uploader=requestUser).exists()
# return obj.filter(uploader=requestUser)
def get_isLiked(self, obj):
requestUser = CurrentUserDefault()
return PostLike.objects.filter(post=obj, liker=requestUser).exists()
#
# try:
# PostLike.objects.get(post=obj, liker=requestUser)
# return True
# except:
# return False
I tried lot of dirty stuffs. but there was no solution..
conclusion:
HTF to get data about, if user has a record of PostLike(post=post, user=user)
how to get user in serializer Class.
or should I approach this in different ways?
like managing liked data in APIView or whatever etc...
help!
========EDITED==========
final code should look like this.
in serialziers.py
class PostListSerializer(serializers.ModelSerializer):
uploader = UserDetailSerializer()
postComments = PostCommentSerializer(many=True, allow_null=True)
postLikes = PostLikeSerializer(many=True, allow_null=True)
postImages = PostImageSerializer(many=True, allow_null=True)
isMine = serializers.SerializerMethodField()
isLiked = serializers.SerializerMethodField()
class Meta:
model = Post
fields = ('uploader', 'id', 'likes', 'content', 'uploadedTime', 'postComments', 'postLikes', 'postImages', 'isMine', 'isLiked',)
def get_isMine(self, obj):
requestUser = self.context['request'].user
return obj.uploader == requestUser
def get_isLiked(self, obj):
requestUser = self.context['request'].user
return PostLike.objects.filter(post=obj, liker=requestUser).exists()

Answer 1

You can get a user from serializer context inside serializer method:
self.context['request'].user
It passed from a method get_serializer_context which originally created in a GenericAPIView:
class GenericAPIView(APIView):
....
def get_serializer_context(self):
"""
Extra context provided to the serializer class.
"""
return {
'request': self.request,
'format': self.format_kwarg,
'view': self
}
As you can see you could also get format and view from context. You could also override this method for set additional context.

Answer 2

def get_isLiked(self, obj):
requestUser = self.context['request'].user
return PostLike.objects.filter(post=obj, liker=requestUser).exists()
If results have 12 objects it will execute 12 similar query, which increase increase your response time. I am looking for solution so that I can make it with one query. Don't know how can I do that.

Answer 3

def get_isLiked(self, obj):
requestUser = self.context['request'].user
return PostLike.objects.filter(post=obj, liker=requestUser).exists()
You should to get all PostLike fields in cache and use prefetch_related method in your query set. This thing will check all entries using cache, not multiple queries.
For example:
def get_isLiked(self, obj):
requestUser = self.context['request'].user
likes = PostLike.objects.all()
return likes.filter(post=obj, liker=requestUser).exists()
and somewhere in models or views or managers in "get_queryset" you should add:
queryset.prefetch_related('postlike')