How to use object.id to make another object, creator of the current object?

Question

I have two models in my django application 'Client' and 'Installment'. Below is my models.py:

models.py

rom django.db import models
from django.utils import timezone
from django.urls import reverse
# Create your models here.


class Client(models.Model):
    name = models.CharField(max_length = 100)
    dob = models.SlugField(max_length = 100)
    CNIC = models.SlugField(max_length = 100)
    property_type = models.CharField(max_length = 100)
    down_payment = models.IntegerField()
    date_posted = models.DateTimeField(default=timezone.now)

    def __str__(self):
        return self.name


    def get_absolute_url(self):
        return reverse('client_details',kwargs={ 'pk' : self.pk})

class Installment(models.Model):
    client = models.ForeignKey(Client, null=True, on_delete=models.CASCADE)
    installment_month = models.CharField(max_length = 100)
    installment_amount = models.IntegerField()
    installment_date = models.DateTimeField(default=timezone.now)

    def __str__(self):
        return self.installment_month

    def get_absolute_url(self):
        return reverse('installment_confirmation')

and my views.py

view.py

# To create new client
class ClientCreateView(CreateView):
    model = Client
    fields = ['name', 'dob', 'CNIC', 'property_type', 'down_payment']


# To add new installment

class AddInstallmentView(CreateView):
    model = Installment
    #template_name = "property_details/addinstallment_form.html"
    fields = ['installment_month', 'installment_amount']

And the URL that I have to add a new installment is below:

urlpatterns = [
    path('', ClientListView.as_view(), name='client_list'),
    path('new/', ClientCreateView.as_view(), name='add_client'),
    path('<int:pk>/', ClientDetailView.as_view(), name='client_details'),
    path('<int:pk>/Add-Installment', AddInstallmentView.as_view(), name='add_installment'),
    path('confirmation/', views.installment_added, name='installment_confirmation'),
]

You can see that the URL for adding new installment is unique. For example,

/<local_server_addr>/<client.id>/Add-Installment (because of <int:pk> above)

I can create a new client and also I can add installment.

But how to connect an installment to a particular client?

How to use this client.id as an owner of the current installment?

It looks like, when one client is created, it is being assigned with some ID from django. Now, how can I use that ID to link it to the installment that I am going to add?

If it's for the current user you have the id in the request. Else you can just pass the client_id in the url as well — Tartempion34, Apr 01 '21 at 05:15
Can you please elaborate your point a bit. I didn't completely understand. — Raza Javed, Apr 01 '21 at 07:13

score 1 · Accepted Answer · answered Apr 02 '21 at 00:23

You can do that by overriding the form_valid method to set the client.id as the owner, this is solved in this question, but in this case we use the client id from the URL parameters:

# To add new installment
class AddInstallmentView(CreateView):
    model = Installment
    #template_name = "property_details/addinstallment_form.html"
    fields = ['installment_month', 'installment_amount']

    def form_valid(self, form):
        # here you get the client id/pk from the url parameters
        form.instance.client = get_object_or_404(Client, pk=self.kwargs['pk'])
        return super(AddInstallmentView, self).form_valid(form)

Then to get all the installments linked to a client you could do:

client = Client.objects.get(SOME_FILTER)
installments = client.installment_set.all()

How to use object.id to make another object, creator of the current object?

1 Answers1