根据特定字段从Django中的数据库获取不同的行 [英] Getting distinct rows based on a certain field from a database in Django

问题描述

我需要在Django中构造一个查询，我想知道这是否有可能（它确实很明显，但我很想念...）。

I need to construct a query in Django, and I'm wondering if this is somehow possible (it may be really obvious but I'm missing it...).

我有一个普通查询 Model.objects.filter（x = True）[：5] ，它可以返回如下结果：

I have a normal query Model.objects.filter(x=True)[:5] which can return results like this:

FirstName    LastName    Country
Bob           Jones        UK
Bill          Thompson     UK
David         Smith        USA

我只需要抓取根据而不同的行Country 字段，例如 Model.objects.filter（x = True）.distinct（'Country'）[：5]

I need to only grab rows which are distinct based on the Country field, something like Model.objects.filter(x=True).distinct('Country')[:5] would be ideal but that's not possible with Django.

我希望查询最终获取的行是：

The rows I want the query to grab ultimately are:

FirstName    LastName    Country
Bob           Jones        UK
David         Smith        USA

I还需要查询使用与模型的Meta类中设置的顺序相同的顺序（即我无法以任何方式取消排序。）

I also need the query to use the same ordering as set in the model's Meta class (ie. I can't override the ordering in any way).

我将如何去做呢？

非常感谢。

推荐答案

我还没有对此进行测试，但是在我看来，尽管订购了dict，但字典还是可以胜任的可能会关闭：

I haven't tested this, but it seems to me a dict should do the job, although ordering could be off then:

d = {}
for x in Model.objects.all():
    d[x.country] = x

records_with_distinct_countries = d.values()

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