Re: how can I reference a field from one model to another model

On 24/01/2019 5:28 pm, carlos wrote:
> Hello,
> I do not know if I'm asking the question correctly, but I need to call
> a field of one model in another model
> example:
> class ModelDad(models.Model):
>     name = blablabla
>
> class ModelChild1(....):
>    fk(ModelDad)
>    number = models.IntegerField()
>
> class ModelChild2(....):
>   fk(ModelDad)
>   another_number = models.IntegerField()
>
>    def make_proces(self):
>       return self.another_number * ModelChild1.number #this is my question
>
> how can I send a call number within the function (make_proces ) of
> ModelChild2

You need a mechanism to find ModelChild1 and the Django ORM provides
Queries for exactly that.

There is a default model manager called 'objects' which you can use to
find instances of models. By that I mean you can pinpoint a row in the
database table which that model represents. For example ... (but to make
it clearer I'll adjust your models above slightly)

class ModelDad(models.Model):
    name = blablabla

class ModelChild1(models.Model):
   dad = models.ForeignKey(ModelDad)
   number = models.IntegerField()

class ModelChild2(models.Model):
   dad = models.ForeignKey(ModelDad)
   another_number = models.IntegerField()

   def make_proces(self):
        child1 = ModelChild1.objects.get(dad=self.dad)
        return self.another_number *child1.number

Visit Django documentation https://docs.djangoproject.com and scroll
down past "First steps" to  "The model layer" and click on a link in the
"Quersets" line. The answers will be in there.

>
> is posible????
>
>
>
> --
> att.
> Carlos Rocha
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