CODEWITHSUNDEEP
pythondjangodjango-modelsforeign-keysdjango-queryset
Peter
Peter

Reputation: 43

How can I do to access to a foreign key in the other side?

I am working a on projects using Django. Here is my models.py :

class Owner(models.Model):
    name = models.CharField(max_length=200)

class Cat(models.Model):
    owner = models.ForeignKey(Owner, on_delete=models.CASCADE)
    pseudo = models.CharField(max_length=200)

I did that :

first_owner = Owner.objects.get(id=1)

And I would like to do something like that

first_owner.Cat

to get all the cats from an owner

I know I can do something like that :

first_cat = Owner.objects.get(id=1)

owner = first_cat.owner

But I would like the reverse operation without using ManyToMany field because every cats has an only owner in my case.

My aim is to do that using only one query.

Upvotes: 1

Views: 89

Answers (2)

Divya Prakash
Divya Prakash

Reputation: 1004

You can add related_name in your model and use it for get all objects referenced as ForeignKey from the given field like below:

class Cat(models.Model):
    owner = models.ForeignKey(Owner, on_delete=models.CASCADE, 
             related_name='cats') #---> you can put whatever related_name you want 
    pseudo = models.CharField(max_length=200)

and query it like this:

first_owner = Owner.objects.get(id=1)
all_instances = first_owner.cats.all()

You will get all objects referenced as ForeignKey in your Cats model.

Upvotes: 3

Sunderam Dubey
Sunderam Dubey

Reputation: 8837

To get all Cat instances from Owner instance in the view you can do:

first_owner = get_object_or_404(Owner,id=1)

all_instances = first_owner.cat_set.all()

In the template you can do it as:

{% for owner in first_owner.cat_set.all %}
   {{owner.psuedo}}

{% endfor %}

Upvotes: 1

Related Questions