本文介绍了如何使用mongodb聚合并检索整个文档的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我对mongodb的聚合函数感到困惑.我只想在我的收藏集中找到最新的文件.假设每个记录都有一个创建"字段
I am seriously baffled by mongodb's aggregate function. All I want is to find the newest document in my collection. Let's say each record has a field "created"
db.collection.aggregate({ $group: { _id:0, 'id':{$first:"$_id"}, 'max':{$max:"$created"} } })产生正确的结果,但是我需要整个文档吗?我该怎么办?
yields the correct result, but I want the entire document in the result? How would I do that?
这是文档的结构:
{ "_id" : ObjectId("52310da847cf343c8c000093"), "created" : 1389073358, "image" : ObjectId("52cb93dd47cf348786d63af2"), "images" : [ ObjectId("52cb93dd47cf348786d63af2"), ObjectId("52f67c8447cf343509d63af2") ], "organization" : ObjectId("522949d347cf3402c3000001"), "published" : 1392601521, "status" : "PUBLISHED", "tags" : [ ], "updated" : 1392601521, "user_id" : ObjectId("52214ce847cf344902000000") }推荐答案
在文档中,我发现 $$ROOT 表达式解决了此问题.
In the documentation i found that the $$ROOT expression addresses this problem.
从DOC: docs.mongodb/手册/参考/操作员/汇总/组/#group-documents-by-author
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如何使用mongodb聚合并检索整个文档
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