如何聚合数组中匹配的值然后排序

Question

我有这些合集：

lists
{_id: 1, item: "a", owner: 1}
users
{_id: 1, subs: [{_id: 1, active: "Y"},{_id: 2, active: "N"}]}
subs
{_id: 1, text: "A"}
{_id: 2, text: "B"}

我想要一个包含用户信息和活动订阅者信息的列表结果。

{_id: 1, item: "a", owner: {_id: 1, subs: [{_id: {_id: 1, text: "A"}, active: "Y"}]}}

我还想根据“文本”字段对其进行排序。

我尝试聚合但失败了，

db.getCollection("lists").aggregate(
[
    { 
        "$lookup" : { 
            "from" : "users", 
            "localField" : "owner", 
            "foreignField" : "_id", 
            "as" : "owner"
        }
    }, 
    { 
        "$match" : { 
            "owner.0.subs" : { 
                "$elemMatch" : { 
                    "active" : "Y"
                }
            }
        }
    }
], 
{ 
    "allowDiskUse" : false
}
);

我也在使用 Mongoose，但使用 populate 失败了。有什么办法可以得到我的结果吗？

在这里，我更新了我的聚合管道，

[
  {
    $lookup: {
      from: "users",
      as: "owner",
      let: { owner: "$owner" },
      pipeline: [
        { $match: { $expr: { $eq: ["$$owner", "$_id"] } } },
        { $unwind: { path:"$sub", preserveNullAndEmptyArrays: false} },
        { $match: { "subs.active": "Y" } },
        {
          $lookup: {
            from: "plans",
            localField: "subs._id",
            foreignField: "_id",
            as: "subs.plans"
          }
        },
        { $unwind: { path:"$subs.plans", preserveNullAndEmptyArrays: false} },
      ]
    }
  },
  { $unwind: { path: "$owner", preserveNullAndEmptyArrays: true} },
  { '$sort': { item: 1 } },
  { '$skip': 0 },
  { '$limit': 20 } ]

Answer 1

您可以使用管道查找和嵌套查找，

内部查找管道是：

$match 您在用户中的所有者 ID collection
$unwind 解构 subs 数组，因为我们需要使用 subs collection
$match 订阅者是否活跃
$lookup 有替补 collection
$unwind 解构我们从 subs collection

subs._id

$group重构subs数组
$unwind解构owner数组
$sort 通过 item 和分页通过 $skip 和 $limit

db.getCollection("lists").aggregate([
  {
    $lookup: {
      from: "users",
      as: "owner",
      let: { owner: "$owner" },
      pipeline: [
        { $match: { $expr: { $eq: ["$$owner", "$_id"] } } },
        { $unwind: "$subs" },
        { $match: { "subs.active": "Y" } },
        {
          $lookup: {
            from: "subs",
            localField: "subs._id",
            foreignField: "_id",
            as: "subs._id"
          }
        },
        { $unwind: "$subs._id" },
        {
          $group: {
            _id: "$_id",
            subs: {
              $push: {
                _id: "$subs._id._id",
                text: "$subs._id.text",
                active: "$subs.active"
              }
            }
          }
        }
      ]
    }
  },
  { $unwind: "$owner" },
  { $sort: { item: 1 } },
  { $skip: 0 },
  { $limit: 20 }
], { allowDiskUse: false })

Playground

你的第二次编辑：在第一个 $unwind 中的第一次查找中有错误的键名 sub，更正此，

{ $unwind: { path:"$sub", preserveNullAndEmptyArrays: false} }

到

{ $unwind: { path:"$subs", preserveNullAndEmptyArrays: false} }

Your Working Query

如何聚合数组中匹配的值然后排序

How to aggregate with value matched in an array then sort

aggregate

mongoose

mongodb

aggregation-framework

mongoose-populate