先用null对日期排序

I'm trying to find documents in a collection, ordered by their date. This works, but I get the documents with null in the date field at the bottom, I want these first.

我想在一个集合中找到文件，按日期排序。这是可行的，但是我在底部的日期字段中获得了null的文档，我首先需要这些。

MyModel.find({ }, null, { sort: { date: -1 } }, function(err, models) {
    // Models sorted with the "largest" date first and models with null dates last
});

If I change the sorting to { date: 1 } I do get the documents with null at first, but the order otherwise is reverse, which I do not want.

如果我将排序更改为{date: 1}，我首先确实获得了具有null的文档，但是顺序相反，这是我不希望看到的。

How can I achieve the desired behaviour?

我怎样才能达到理想的行为?

1 个解决方案

#1

Unfortunately it appears there's no trivial way to do this, akin to SQL's "nulls first" / "nulls last" syntax. This feature is mentioned in this Mongo bug:

不幸的是，似乎没有简单的方法可以做到这一点，类似于SQL的“nulls first”/“nulls last”语法。这个特性在Mongo bug中提到:

https://jira.mongodb.org/browse/SERVER-153

https://jira.mongodb.org/browse/server - 153

Where it's looped in with the larger feature of custom sorting functions. (I really wish this were broken out into a separate feature request because I would think implementing only the nulls first/last bit should be much easier than custom sorting functions and still provide a lot of value.)

它与自定义排序函数的更大特性相关联。(我真的希望将它分解成一个单独的特性请求，因为我认为只实现null first/last位应该比自定义排序函数容易得多，并且仍然提供很多价值。)

Anyway, the work-around for the time being is to just query separately for the null values in addition to your existing query:

不管怎样，目前的解决方法是除了现有查询之外，单独查询空值:

How are null values in a MongoDB index sorted?

MongoDB索引中的空值如何排序?

MyModel.find({ date: null });
MyModel.find({ date: { $ne: null } }).sort({ date: -1 } });

#1