about cacade foreignkey in django admin page - django

Question

My model is like below:
class Manufacturers(models.Model):
name = models.CharField()
class Phones(models.Model):
manufacturer = models.ForeignKey(Manufacturers)
name = models.CharField()
class Prices(models.Model):
phone = models.ForeignKey(Phones)
price = models.DecimalFeild()
and I have registered them in the admin.py
My problem is:
In django's admin interface, When I add a price, I can select a phone from the dropdown list, But there are so many phones, So I want to select the manufacturer at first, then select the phone from the manufacturer's phones. How can I make this.
Thanks very much.

Answer 1

The term for this is "chained select menus".
There are a number of implementations in django. One that you may find useful is django-smart-selects.
Using django-smart-selects, this is how you would write up your models:
class Manufacturers(models.Model):
name = models.CharField()
class Phones(models.Model):
manufacturer = models.ForeignKey(Manufacturers)
name = models.CharField()
class Prices(models.Model):
phone = ChainedForeignKey(
Phone,
chained_field="manufacturer",
chained_model_field="manufacturer",
show_all=False,
auto_choose=True
)
price = models.DecimalField()
All that said, I wonder if you are implementing this in the best fashion.
It might be better to have Prices show up under the admin form for each phone. So instead of creating a price record and choosing the phone from a drop-down, you'd go into the record for that phone and add a price record. See django's documentation on InlineModelAdmin.