adding additional fields to serializer from another model

Question

I am going to include Model to another serilializer in my project here is the specification. I have a Review model as follows

class Review(models.Model):
    profile = models.ForeignKey(Profile, on_delete=models.CASCADE)
    product = models.ForeignKey(Product, on_delete=models.CASCADE)
    rating= models.ForeignKey(ProductRating, on_delete=models.DO_NOTHING)
    comment = models.TextField()

my function is to show number of comment that users wrote for the product and I should show in serializer like that

class WishList(models.Model):
    user = models.ForeignKey('authentication.User', on_delete=models.CASCADE, null=True)
    product = models.ForeignKey(Product, on_delete=models.CASCADE, null=True)

serailzier.py

class GetWishlistSerializer(serializers.ModelSerializer):

name = serializers.CharField(source='product.name', read_only=True)
rating = serializers.IntegerField(source='product.rating', read_only=True)
image = serializers.ImageField(source='product.image', read_only=True)
price = serializers.DecimalField(source='product.price', decimal_places=2, max_digits=10, read_only=True)
review = SerializerMethodField()

class Meta:
    model = WishList
    fields = ['user','product', 'name', 'rating', 'image', 'price', 'description', 'review']

def get_review(self, obj):
    return Review.objects.filter(product_id=obj.id).count()

and it should count the number of review for specified product but it did not work it gives result like that.

{
            "user": 1,
            "product": 1,
            "name": "Samsung A70",
            "rating": 5,
            "image": "http://localhost:8000/media/products/2019/08/30/wkl6pb_E2RUzH6.jpeg",
            "price": "2500.00",
            "description": "bla bla bla",
            "review": 0
        }

but I have one review for product: 1 it should show 1 but it shows 0 I do not know what I am missing here. Any help please? If question is unclear please let me know I will try to specify in more detail

Jaskaran Singh · Accepted Answer · 2019-09-24 18:58:55Z

1

The issue is with the query. Instead of

# comparing it with wishlist pk instead of wishlist's pro
Review.objects.filter(product_id=obj.id).count()

but it should get the products review

def get_review(self, obj):
    return Review.objects.filter(product_id=obj.product.id).count()

answered Sep 24, 2019 at 18:58

Jaskaran Singh

1691 silver badge7 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

hancho · Accepted Answer · 2019-09-24 15:19:16Z

0

I would use .annotate

from django.db.models import Count

WishList.objects.annotate(review_count=Count('product__review_set')

Check what the related name is for review on product but it should be review_set if you did not define it.

Then add 'review_count' to WishListSerializer fields.

review_count = serializers.IntegerField(required=False)

You'd annotate onto the queryset in the ViewSet. I'd overwrite get_queryset

answered Sep 24, 2019 at 15:19

hancho

1,4573 gold badges24 silver badges44 bronze badges

Collectives™ on Stack Overflow

adding additional fields to serializer from another model

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related