如何对数组内部的mongo文档中的字段进行排序 [英] how to sort the field in the mongo document which is inside array

问题描述

下面有一个结构化的Mongo文档:

I have below a structured Mongo Document:

{
  "_id": value,
  "imageShared": {
    "imageid": value,
    "commentdatadoc": [
      {
        "whocommented": value,
        "commenttext": value,
        "commenttimestamp": isodate(111)
      },
      {
        "whocommented": value,
        "commenttext": value,
        "commenttimestamp": isodate(444)
      },
      {
        "whocommented": value,
        "commenttext": value,
        "commenttimestamp": isodate(222)
      }
    ]
  }
};

在这里，我想对字段commenttimestamp desc进行排序.我尝试了下面的方法，但是它不起作用...

Here I want to sort the field commenttimestamp desc. I tried the way below but it is not working...

Query getComments = new Query();
getComments.addCriteria(Criteria.where("imageShared.imageId").is(imageId)).
    with(new Sort(Sort.Direction.DESC,"imageShared.commentDataDoc"));
    SharedMediaCollec sharedMediaCollec = mongoTemplate.findOne(getComments, SharedMediaCollec.class);

有人知道如何对数组内部的文档字段进行排序吗?

Does anyone have an idea how to sort a document field which is inside array?

推荐答案

无论如何，您都需要获取所有文档时，从MongoDB接收数据后，使用C#进行排序可能会容易得多.自动执行此操作的一种优雅方法是使用

When you need to get all documents anyway, it might be far easier to do the sorting in C# after you received the data from MongoDB. An elegant way to do this automatically would be to represent the commentdatadoc array in your C# object with a SortedSet.

但是，如果您确实需要数据库方面的解决方案，则可以使用聚合管道，包括一个$ match步骤，一个$ unwind步骤和一个$ sort步骤.要使用C#驱动程序执行聚合，请先调用 collection.Aggregate 将聚集阶段设置为返回的IAggregateFluent接口.

But when you definitely want a database-sided solution, you can do it with an aggregation pipeline consisting of a $match-step, a $unwind step and a $sort step. To perform an aggregation with the C# driver, call collection.Aggregate and then set the aggregation stages at the returned IAggregateFluent interface.

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