通过DBRef数组查找文档 [英] Finding documents by array of DBRefs

问题描述

解决方案可能正盯着我，但我没有找到任何运气.我的问题是我需要查找包含指定DBRef的所有文档.这是要搜索的集合的结构:

The solution is probably staring me in the face, but I haven't had any luck in finding it. My problem is that I need to find all documents which contain specified DBRef. Here's the structure of the collection to be searched:

{
    "_id" : ObjectId("4e2d4892580fd602eb000003"),
    "date_added" : ISODate("2011-07-25T11:42:26.395Z"),
    "date_updated" : ISODate("2011-07-25T11:43:09.870Z"),
    ...
    "a_list_of_dbrefs" : [
        {
            "$ref" : "somecollection"
            "$id" : "4e2d48ab580fd602eb000004"
        }
    ],
    ...
    "name" : "some name"
}

我需要能够基于出现在a_list_of_dbrefs中的DBRef检索一组文档(有些a_list_of_dbrefs可能不包含DBRef，有些可能包含1，有些可能包含多个).

I need to be able to retrieve a set of documents based on a DBRef appearing in a_list_of_dbrefs (some a_list_of_dbrefs may contain no DBRefs, others may contain 1, and others may contain more than 1).

这是如何完成的?

推荐答案

我建议转储DBRef，而假定您知道所引用集合的名称，而只需简单地存储所引用文档的_id即可.

I'd recommend dumping the DBRefs in favor of simply storing the _id of the referenced document assuming you know the name of the collection being referenced.

在MongoDB上，绝对没有办法从服务器端(一步)解析"一个DBRef数组，并且需要您遍历客户端上的数组并分别解析每个文档.

There is absolutely no way to "resolve" an array of DBRef from the server-side (in a single step) on MongoDB and requires that you loop through the array on the client and individually resolve each document.

相反，如果您存储的只是引用的_id数组，则可以检索该数组，然后使用$in查询将其全部获取.

Conversely, if you store an array of just the referenced _id you can retrieve that array and then use the $in query to fetch them all.

因此，您的文档可能会变成这样:

So your document might change to look like this:

{
    "_id" : ObjectId("4e2d4892580fd602eb000003"),
    "date_added" : ISODate("2011-07-25T11:42:26.395Z"),
    "date_updated" : ISODate("2011-07-25T11:43:09.870Z"),
    ...
    "references": [
        ObjectId(123), ObjectId(234), ObjectId(567), ObjectId(891)
    ],
    ...
    "name" : "some name"
}

然后您可以使用references字段的内容查询MongoDB:

You can then query MongoDB using the contents of the references field:

db.somecollection.find({"_id": {"$in": references}})

这篇关于通过DBRef数组查找文档的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！