Django annotate Count does not work on Many to Many table

Question

I have a hierarchy of Django models (reduced to the essentials):

project/models.py

class Project(models.Model):

    @property
    def material(self):
        return = m2m_Assembly_Components.objects.filter(assembly__room__project = self).aggregate(count=models.Count('component'))


class Room(models.Model):

    project = models.ForeignKey("Project", related_name="rooms")

class Assembly(models.Model):

    room = models.ForeignKey("Room", related_name="assemblies")
    components = models.ManyToManyField("material.Component", through="m2m_Assembly_Components")

class m2m_Assembly_Components(models.Model):

    component = models.ForeignKey("material.Component")
    assembly = models.ForeignKey("Assembly")

material/models.py

class Component(models.Model):

    name = models.CharField(max_length=200)

I want to get a list of all component entries in m2m_Assembly_Components which are related to a certain Project and their number.

Something like "Project 1 has 7 Components of type A and 3 Components of type B"

To do so I use the material property in the Project class, but I just get a list of m2m_Assembly_Components objects and a count value of 1.

Can anybody give me a hint what I'm doing wrong!?

Edit 07.042016 12:11

I got it kind of working, but not in a nice way:

 @property
 def material(self):
     return = m2m_Assembly_Components.objects.filter(assembly__room__project = self).values('component__name','component__articlenumber').annotate(count=models.Count('component'))

Unfortunately this gives me a dict instead of an object and i have to define all the values i need:

{'component__articlenumber': '021123', 'count': 17, 'component__name': 'Abdeckrahmen, E2, anthrazit, 1-fach'}