How to get all the Students enrolled to a list of Specific Courses say (1 and 2) in a many to many relationship

Question

I'm trying to get all the Students which are enrolled to a list of specific courses (Say Course 1 and Course 2).

class Student(models.Model):
    name = models.CharField(max_length=50, verbose_name="Student name")
    courses = models.ManyToManyField(Course, related_name="students", blank=True)

    def __str__(self):
        return self.name


class Course(models.Model):
    name = models.CharField(max_length=100, verbose_name="Course Name")

    def __str__(self):
        return self.name

If I do:

result = Student.objects.filter(courses__in=[1,2])

I get all the Students who are enrolled with either course 1 or course 2. I'm interested only in students who are enrolled in both courses.

The below code works but I think it's not the best way to accomplish this:

all_students = Student.objects.all()
stud_id = []
for student in all_students:
    course_list = list(student.courses.values_list('pk', flat=True))
    check = all(item in course_list for item in [1,2])
    if check:
        stud_id.append(student.id)
studs = Student.objects.filter(id__in=stud_id)

The idea is to not loop over every student to find if they're enrolled to the given set of courses.

mseromenho mseromenho · Accepted Answer · 2021-05-11T13:08:11

As @Ashley H. indicated, but instead:

result = Student.objects.filter(courses__id=1).filter(courses__id=2)

So if we have:

Joe Ben: Math, Computing, Machine Learning
Ray Youth: Math, Computing
Elli Vader: Computing

The result would be: Joe Ben, Ray Youth. I assume this is what is needed. Can you correct me if not?

How to get all the Students enrolled to a list of Specific Courses say (1 and 2) in a many to many relationship

2 Answers