How to access foreign key while validating form in django?

Question

In the django project I was working on, there are classes named Course and Assignment . Assignment is related to Course by foreignkey as shown here:

class Assignment(models.Model):
    course = models.ForeignKey(Course, related_name='get_assignments')

So every course has few assignments. To create assignments in a course, form named AssignmentForm is used. In the assignment form, while validating it, in a function, I want to get the name of Course in which assignment is created. How should I get that?

This is what I've done:

    def clean_bulk_add(self):
        assig1 = self.cleaned_data['name']
        course1 = self.this_course
        user1 = course1.owner
        tot1 = 30 + len(str(user1)) + len(str(course1.title)) + len(str(assig1)) + len(str(self.cleaned_data['bulk_add']))
        if tot1 > 7 :
            raise forms.ValidationError("Assignment or Course name is too long: "+str(tot1))
        return self.cleaned_data['bulk_add']

Error I got:

Answer 1

You should have something like this,

class AssignmentForm(forms.ModelForm):
    class Meta:
        model = Assignment
        fields = ['course']

    def clean_course(self):
        course = self.cleaned_data['course']
        course_name = course.name

        # do some validation on course_name 

        return course