使用mongodb/mongoid排序时，是否可以将所有nil值放在末尾? [英] Is there a way to put all the nil value at the end when sorting with mongodb/mongoid?

问题描述

要说的真的不多于问题中已经存在的内容.

Really not much more to tell than what is already in the question.

使用蒙古型:

People.asc(:age)

我先得到nil值.
是否有办法始终返回nil last ，或告诉mongodb将nil视为非常高?

I get nil value first.
is there a way to always return nil last, or to tell mongodb to treat nil as very high?

与所遇到的问题完全相同这里

推荐答案

我很确定MongoDB的答案是否".无法提供自定义排序功能，只能提供要进行排序的键. 对自定义排序功能的请求，它们甚至提到您的特定用例:

I'm pretty sure the answer is "no" for MongoDB. There's no way to supply a custom sorting function, you can only supply the keys to sort on. There is a request for custom sorting functions and they even mention your particular use case:

用于自定义排序/索引的javascript排序助手
[...]
可以将其用于按字母顺序对字段进行排序，然后将具有空值的文档放在结果集的末尾吗?
[...]
@nick-是

javascript sort helper for custom sorting / indexing
[...]
Could this be used to sort alphabetically on a field, and put documents with a null value at the end of the result set?
[...]
@nick - yes

因此，您并不是一个人只想将null放在一端或另一端.

So you're not alone in wanting to put nulls at one end or the other.

我认为您现在可以做的最好的就是在Ruby中进行操作，如下所示:

I think the best you can do right now is to do it in Ruby, something like this:

nils, not_nils = People.asc(:age).partition { |p| p.age.nil? }
people = not_nils + nils

我不使用Mongoid，但是asc大概可以给你一个Enumerable，如果没有的话，也许您可​​以在其中插入to_a.当然，如果您要分页，这种黑客手段就没用了.

I don't use Mongoid but presumably asc gives you an Enumerable, if not then perhaps you could stick a to_a in there. Of course this sort of hackery is useless if you're paginating.

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