Question

I dont understand how I can “import”(I dont know the right terminology, so please dont crucify me on this) a Foreignkey from 1 model class to a another:

e.g.

class1 (models.Model):
    variable1 = models.CharField()
    variable2 = models.CharField()

class2 (models.Model):
    variable3 = models.CharField()
    variable4 = class1.variable1 "imported" from class1

So now I have all the data from variable1 from class1 available in class2.

I assume this would be accomplished by a ForeignKey.

If I take the example of the official Django documentation (see below), I dont get my answer because:

1. Why does it only mention the other model and not the variable I create from it.

2. This would be for a future model, where I dont know the fields yet. But i know the fields already. Again no variable, just the model.

3. This would be what I am looking for. But this is “imported” from another app. But with me it is in the same app.

ad 1.

class ForeignKey(othermodel[, **options])¶

ad 2.

class Car(models.Model):
    manufacturer = models.ForeignKey('Manufacturer')
    # ...

class Manufacturer(models.Model):
    # ...

ad 3.

class Car(models.Model):
    manufacturer = models.ForeignKey('production.Manufacturer')

Thanks!

Answer 1

If I understand your question correctly.

You are establishing the relationship to the whole model with a foreign key, not just one field, so you will have access to all the fields, even if you only want one.

variable4 = models.ForeignKey(class1)

now you can say variable4.variable1 or variable4__variable2 in a queryset.

Re point 2 – use variable4 = models.ForeignKey(‘class1’) if class1 not already defined
Re point 3 – no need to add application if model in the current application.