如何连接来自 MongoDB 中多个文档的数组?

本文介绍了如何连接来自 MongoDB 中多个文档的数组?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

假设我有一个名为people"的集合，其中包含以下文档:

Let's say I have a collection called 'people' with the following documents:

{ "name": "doug", "colors": ["blue", "red"] } { "name": "jack", "colors": ["blue", "purple"] } { "name": "jenny", "colors": ["pink"] }

我如何获得所有 colors 子数组的串联数组，即?

How would I get a concatenated array of all the colors subarrays, i.e.?

["blue", "red", "blue", "purple", "pink"]

推荐答案

尝试使用聚合:

db.people.aggregate([ {$unwind:"$colors"}, {$group:{_id:null, clrs: {$push : "$colors"} }}, {$project:{_id:0, colors: "$clrs"}} ])

结果:

{ "result" : [ { "colors" : [ "blue", "red", "blue", "purple", "pink" ] } ], "ok" : 1 }

更新

如果你想在结果的数组中获得唯一值，你可以使用 $addToSet 运算符而不是 $group 阶段中的 $push.

If you want to get unique values in result's array, you could use $addToSet operator instead of $push in the $group stage.