Django DetailView: related objects

Question

Got 4 Models:

models.py

class Buildings(models.Model):
    name = models.CharField(max_length=25)

class Zones(models.Model):
    name = models.CharField(max_length=25)

class Departments(models.Model):
    name = models.CharField(max_length=25)
    zone = models.ForeignKey(Zones, related_name='departments')

class Rooms(models.Model):
    name = models.CharField(max_length=25)
    department = models.ForeignKey(Departments, related_name='rooms')
    building = models.ForeignKey(Buildings, related_name='buildings')

What I'm trying to do is:

Create DetailView of a Buildings in which we see:

• departments inside the building
• rooms inside the building
• zones each room belongs to

Now in views.py I have:

class BuildingsDetailView(DetailView):
    model = Buildings

    def get_context_data(self, **kwargs):
        context = super(BuildingsDetailView, self).get_context_data(**kwargs)
        context['Rooms'] = Rooms.objects.filter(building=self.get_object())
        context['Zones'] = Zones.objects.filter(departments__rooms__buildings=self.get_object())
        return context

detail.html In DetailView I can now access Rooms, Departments and Zones but I'cant match Zones to Rooms. It prints buildings and rooms with departments correctly, then multiplies it with all Zones in building.

{% for rm in Rooms %}
    {% for zn in Zones %}
        <p> {{ rm.name }} </p>
        <p> {{ rm.department }} </p>
        <p> {{ zn.name }} </p>
    {% endfor %}
{% endfor %}

Output:

Room 1
Depart A
Zone 1

Room 1
Depart A
Zone 2

etc.

How can I match Zone name to corresponding Department of each Room in a Building correctly? Room and Depart name is matched correctly.

Answer 1

You are looping over separate querysets which won't match up, just access the related models from the instance you have. Try this in the template:

{% for rm in Rooms %}
    <p> {{ rm.name }} </p>
    <p> {{ rm.department }} </p>
    <p> {{ rm.department.zone.name }} </p>
{% endfor %}