Question

Here is my model:

class Teacher(models.Model):
    name = models.CharField(max_length=50)  
    subjects = models.ManyToManyField(Subject)

class Subject(models.Model):
    name = models.CharField(max_length=50)
    type = models.ForeignKey(SubjectType)   

class SubjectType(models.Model):
    name = models.CharField(max_length=50)

I want to do something like that in template:

{regroup subjects by subject.type}
  {foreach subject_type}
    #display all teachers for subject_type         

Each subject has its teacher_set.
How can i union all teachers for a particular subject_type?

Answer 1

I think you can’t get this functionality from the template. However, you could do it in your view:

subject_type = # Some SubjectType object
my_teachers = []
for subject in subject_type.subject_set:
    my_teachers += subject.teacher_set
# What we do with the duplicates?
my_teachers = list(set(my_teachers))

Now, you have a list of unique teachers in my_teachers for a particular SubjectType.

EDIT: You could do this for every SubjectType object and pass the resulting list (of lists) to the template.