How to implement a dependent drop down list with Django CreateView?

Question

I am trying to create a CreateView for one of my models "service". My "service" model has a foreign key to an "asset" model. "asset" model has a foreign key to the current user.

I would like to populate a drop down in "service" CreateView with all the "assets" owned by the current logged in "user".

Service model

class Service(models.Model):
    name = models.CharField(max_length=100)
    category = models.CharField(max_length=100)
    provider = models.CharField(max_length=100)
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)
    asset = models.ForeignKey(Asset, on_delete=models.CASCADE)

Asset model

class Asset(models.Model):
    name = models.CharField(max_length=100)
    address = models.CharField(max_length=100)
    suburb = models.CharField(max_length=100)
    postcode = models.CharField(max_length=4)
    state = models.CharField(max_length=3)
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)
    owner = models.ForeignKey(User, on_delete=models.CASCADE)

ServiceCreateView in views.py

class ServiceCreateView(LoginRequiredMixin, CreateView):
    model = Service
    fields = ['name', 'category', 'provider', 'asset']

If I user 'asset' in fields, I get all the assets added to the drop-down list. I need it to be only the assets owned by the current user.

Any help in this much appreciated.

Thank you.

(I am using the Django 2.2)

Answer 1

Modify your ServiceCreateView to use distinct form, specify template and send current user to that form, so it will know for which user it will need to filter asset

views.py:

class ServiceCreateView(LoginRequiredMixin, CreateView):
    form_class = ServiceCreateForm
    template_name = 'service_form.html'

    def get_form_kwargs(self):
        kwargs = super().get_form_kwargs()
        kwargs['user'] = self.request.user
        return kwargs

Create ModelForm with same fields and model, that will take user instance on init and filter your asset field accordingly.

forms.py:

class ServiceCreateForm(forms.ModelForm):
    class Meta:
        model = Service
        fields = ['name', 'category', 'provider', 'asset']

    def __init__(self, *args, **kwargs):
        user = kwargs.pop('user', None)
        super().__init__(*args, **kwargs)

        self.fields['asset'].queryset = self.fields['asset'].queryset.filter(
            owner=user)