i have a model class
Category and also a model class
Course. i want to count all the courses that are related to a model e.g: Web Devlopment - 26 Courses i dont know how to go about this since the this are two diffrent models.
class Category(models.Model): title = models.CharField(max_length=1000) class Course(models.Model): id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False) course_title = models.CharField(max_length=100, null=True, blank=True) course_category = models.ForeignKey(Category, on_delete=models.DO_NOTHING, null=True, blank=True)
First, you need to set the
related_name attribute in the
class Course(models.Model): ... course_category = models.ForeignKey(Category, realted_name="courses" on_delete=models.DO_NOTHING, null=True, blank=True)
Next, you can use this name to aggregate the query as the following.
from django.db.models import Count cateogries = Category.objects.annotate(number_of_courses = Count("courses")).all()
Then, each of the
categories will have the
number_of_courses field that indicates the number of courses.