如何获取ForeignKey模型字段

In Django 1.8

在Django 1.8中

class OtherModel(models.Model):
    somefield = models.CharField(max_length=20)

class Orderform(models.Model):
    sell_item_id = models.CharField(max_length=20)

class Selled(models.Model):
    orderform = models.ForeignKey("Orderform")
    sell_count = models.IntegerField()
    something = OtherModel.objects.get(id=sell_item_id)

I need to use something like OtherModel.objects.get(id=sell_item_id).

我需要使用像OtherModel.objects.get（id = sell_item_id）这样的东西。

How to get sell_item_id in class Selled(models.Model):?

如何在类Selled（models.Model）中获得sell_item_id：？

2 个解决方案

#1

You schema couldn't be presented in SQL.

您的架构无法在SQL中显示。

Option #1:

选项1：

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

and get it

得到它

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

Option #2:

选项＃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

得到

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

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

但我认为你应该更好地考虑一下DB模式。

#2

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

看起来你有几个问题，第一个是获得相关的问题

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.

请注意sell_item_id之前的__（双下划线）。这很重要，因为它说，由OrderForm的sell_item_id选择Selleed。和select_related确保通过单次调用db将订单返回到结果中。

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.

现在，如果您想为OtherModel执行此操作，则需要在OtherNodel中创建类似的ForeignKey字段，这将允许您进行与上面相同的查询。目前，你没有这样的关系。

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:

别忘了跑：

python manage.py makemigration
python manage.py migrate

This should solve the issue.

这应该可以解决问题。

#1