[Fixed]-How to get ForeignKey model field

by

1👍

You schema couldn’t be presented in SQL.

Option #1:

class Orderform(models.Model):
    sell_item_id = models.CharField(max_length=20)
    othermodel = models.OneToOneField("OtherModel")

and get it

Selled.objects.get(pk=1).orderform.othermodel

Option #2:

class Selled(models.Model):
    orderform = models.ForeignKey("Orderform")
    sell_count = models.IntegerField()

    def something(self):
        return OtherModel.objects.get(id=self.sell_item_id)

and get

Selled.objects.get(pk=1).something()

But I think you should better think about you DB schema.

👤Anarchy

0👍

It looks like you have a couple of questions, for the first, to get the related 

Selled.objects.filter(order_form__sell_item_id =id_to_get).select_related('order_form')

Notice the __ (double underscore) before sell_item_id. This is important because it says, selected Selleed by the sell_item_id of the OrderForm. and select_related makes sure that order form is brought back in the results with a single call to the db.

Now, if you want to do that for OtherModel, you will need to create a similar ForeignKey field in the OtherNodel and this will allow you to make the same query as above. Currently, you have no such relation.

class OtherModel(models.Model):
    somefield = models.CharField(max_length=20)
    orderform = models.ForeignKey("Orderform")

OtherModel.objects.filter(order_form__sell_item_id =id_to_get).select_related('order_form')

Don’t forget to run:

python manage.py makemigration
python manage.py migrate

This should solve the issue.

👤Sina Khelil

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