Django ForeignKey Instance vs Raw ID [英] Django ForeignKey Instance vs Raw ID

问题描述

在创建新模型时，有没有办法在外键的模型实例中传递？假设我有以下模型：

Is there a way to not have to pass in a model instance for a foreign key when create a new model? Let's say I have the following models:

class Foo(models.Model):
    description = models.CharField(max_length=100)

    class Meta:
         db_table = u'foo'

class Bar(models.Model):
    info = models.CharField(max_length=100)
    foo = models.ForeignKey('Foo')

    class Meta:
         db_table = u'bar'

稍后的一个帖子请求进入一个视图 - 我知道一个foo记录的id，只是想将一个记录插入到条形表中

The later a post request comes in to a view - I know the the id of a foo record and just want to insert a record into the bar table.

如果我这样做：

new_bar = Bar(info="something important", foo=foo_id)
new_bar.save()

ValueError说无法分配546456487466L：Bar.foo只是一个Foo实例。

I get a ValueError saying "Cannot assign "546456487466L": "Bar.foo" just be a "Foo" instance.

所以，我得到它...希望我有Foo模型的一个实际实例，我明白我可以做一个Foo，然后传入，但是，像ems一样，必须有办法来覆盖这个功能。我已经做了一些搜索和阅读文档，而admin中的raw_id_fields似乎是基本的想法。 （也就是说，允许一个原始ID在这里）。但是，在ForeignKey字段中看不到此选项。

So, I get it... it wants me to have an actual instance of the Foo model. I understand that I can just do a get on Foo and then pass it in. But, there seems like there must be a way to override this functionality. I have done some googling and reading the docs, and raw_id_fields in admin seems to be the basic idea. (which is to say, allow a raw id here). But, don't see this option on the ForeignKey field.

看起来非常低效，不得不做一个往返数据库来获取对象来获取id （我已经有）。我明白，往返行证实数据库中存在id。但是，嘿，这就是为什么我使用RDBMS，并且首先有外键。

It seems very inefficient to have to make a round trip to the database to get an object to get the id (which I already have). I understand that doing the round trip validates that the id exists in the database. But, hey... that's why I'm using a RDBMS and have foreign keys in the first place.

谢谢

推荐答案

new_bar = Bar(info="something important", foo_id=12345)
new_bar.save()

您还可以获取外键值直接。某种优化。

You can also get foreign key values directly. Some kind of optimization.

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