Django教程：什么是choice_set？ [英] Django tutorial: What is choice_set?

问题描述

在Django教程中有这一行，编写你的第一个Django app，part 1 ：

There is this line in the Django tutorial, Writing your first Django app, part 1:

p.choice_set.create(choice='Not much', votes=0)

如何 choice_set 存在，它是什么？

我认为选择 part是模型的小写版本选择在教程中使用，但什么是 choice_set ？您可以详细说明吗？

I suppose the choice part is the lowercase version of the model Choice used in the tutorial, but what is choice_set? Can you elaborate?

更新1 ：根据Ben James '答案我在文档中找到了一个描述的地方： 关系后退 。

Update 1: based on Ben James' answer I located a place in the documentation where it is described: Following relationships "backward".

推荐答案

您在选择中创建了一个外键，其中每个都与 code>。

You created a foreign key on Choice which relates each one to a Question.

所以，每个选择显式地有一个 code>字段，您在模型中声明。

So, each Choice explicitly has a question field, which you declared in the model.

Django的ORM从向后追溯关系问题在每个实例上自动生成一个名为 foo_set 的字段，其中 Foo 是具有 ForeignKey 这个模型的字段。

Django's ORM follows the relationship backwards from Question too, automatically generating a field on each instance called foo_set where Foo is the model with a ForeignKey field to that model.

choice_set 是一个回覆latedManager 可以创建与问题实例相关的选项对象的查询。 q.choice_set.all（）

choice_set is a RelatedManager which can create querysets of Choice objects which relate to the Question instance, e.g. q.choice_set.all()

如果你不喜欢 foo_set 命名Django自动选择，或者如果您有同一型号的多个外键需要区分它们，则可以使用 related_name 参数 ForeignKey 。

If you don't like the foo_set naming which Django chooses automatically, or if you have more than one foreign key to the same model and need to distinguish them, you can choose your own overriding name using the related_name argument to ForeignKey.

这篇关于Django教程：什么是choice_set？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！