how to just access the count of products through another model which are connected by foreign key-CodePudding

class Category(models.Model):
    category_name = models.CharField(max_length=50, unique=True)
    




class Product(models.Model):
    category        = models.ForeignKey(Category, on_delete=models.CASCADE)
    product_name    = models.CharField(max_length=200, unique=True)
    slug            = models.SlugField(max_length=200, unique=True)

Here what i want is just the number of the product present in each category just the number of product i know i have can fire somequery

cat = Category.objects.all()

run loop for cat

prod_cat = Product.object.filter(category=cat)

But i belive its not the efficient way to achive this

CodePudding user response：

By using annotate like this:

from django.db.models import Count

>>> categories = Category.objects.annotate(Count('product'))

>>> categories[0].product__count

CodePudding user response：

Full examples and understanding here: https://able.bio/dfernsby/django-queryset-annotations-with-conditions--19d4cb4b