为什么django在进行过滤器查询时必须使用双下划线？ [英] Why django has to use double underscore when making filter queries?

问题描述

所以在django我们写了

So in django we write

Entry.objects.filter(blog__id=3)

其中看起来很丑陋，因为有时候会出现下划线太多

Which looks ugly because sometimes there are too many underscores

Entry.objects。过滤器（blog_something_ 下划线 _too_ 许多 _id = 3）

Entry.objects.filter(blog_something_underscore_too_many_id=3)

为什么django不能使用像

why django can't use syntax like

[entry.objects if blog.id=3 ]

？

我不是专家，但为什么要双重下划线？可以在python的语法中有一个更优雅的风格来写这个吗？

I am not expert on this, but why must double underscore? Could there be a more elegant style in python's grammar to write this?

推荐答案

Django运行在Python上，它设置了一些基本约束它涉及语法，使以下建议的语法不可能（Python不允许重新定义基本语法）：

Django runs on Python, which sets some basic constraints when it comes to syntax, making the following suggested syntax impossible (Python does not allow much re-definition of basic syntax):

[entry.objects if blog.id=3 ]

此外，博客和id不是对象，它们引用数据库中的名称，所以将这些解释为 blog.id 也是有问题的。除非当然是以字符串的形式输入，实际上，在Python中将字符串对象作为关键字参数进行查看。这当然可以用其他方式完成，下面是一个如何使用点作为分隔符的例子：

Also, "blog" and "id" are not objects, they refer to names in the database, so addressing these as blog.id is also problematic. Unless of course it is entered as a string, which is actually what is being done seeing as keyword arguments are passed as a dictionary objects in Python. It could of course be done in other ways, here is an example of how to use dots as separators:

def dotstyle(dict):
    retdict = {}
    for key, value in dict.items():
         retdict[key.replace(".", "__")] = value
    return retdict

Entry.objects.filter(**dotstyle({"blog.id": 3})

通过将这个结合到Django中的过滤器函数中，我们可以消除dotstyle函数和尴尬的**，但是我们仍然留下字典大括号，这可能是为什么它们与双重下划线。

By incorporating this to the filter function in Django, we could do away with the dotstyle function and the awkward **, but we are still left with the dictionary braces, which is probably why they went with the double underscores instead.

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