node.js - 如何计算组聚合的评分？

Question

我被困在 mongodb 聚合上以获得评分。我已经在努力让自己成为管道。看上面

数据(产品集合)

{
  "status": 200,
  "message": null,
  "data": {
    "_id": "5cc570257631a313d489ba4a",
    "media": [
      "httpsdssd",
      "dfdfd"
    ],
    "comment": [
      "5cc57f1053273c05cc60e707",
      "5cc585bf6ff7a812e0e7d9d9",
      "5cc5c654bc73b408787ffadc",
      "5cc5c6e3bc73b408787ffadd"
    ],
    "store": "5cc2c9710bc5d615781fcf8a",
    "meta": {
      "title": "Traveling Sumbar",
      "price": "150000",
      "max": 5,
      "duration": 6,
      "description": "fdf fdnf jdnf dfnkdknfkkd",
      "location": {
        "province": "Sumbar",
        "city": "Padang"
      }
    },
    "option": {
      "is_promo": false,
      "auto_delete": null
    },
    "created_at": "2019-04-28T09:19:33.233Z",
    "updated_at": "2019-04-28T15:29:39.921Z",
    "__v": 0
  }
}

关于(products_comment)的评论数据

{
    "helped": [],
    "deleted_at": null,
    "_id": "5cc3276e32940613506c3848",
    "user": "5cc2c7fb0bc5d615781fcf86",
    "rating": "4",
    "body": "fdfdlfdlfkdlfkdlfkd",
    "created_at": "2019-04-26T15:44:46.224Z",
    "updated_at": "2019-04-28T16:00:48.400Z",
    "__v": 0
  },
{
    "helped": [],
    "deleted_at": null,
    "_id": "5cc3276e32940613506c3848",
    "user": "5cc2c7fb0bc5d615781fcf86",
    "rating": "4",
    "body": "fdfdlfdlfkdlfkdlfkd",
    "created_at": "2019-04-26T15:44:46.224Z",
    "updated_at": "2019-04-28T16:00:48.400Z",
    "__v": 0
  },
{
    "helped": [],
    "deleted_at": null,
    "_id": "5cc3276e32940613506c3848",
    "user": "5cc2c7fb0bc5d615781fcf86",
    "rating": "3",
    "body": "fdfdlfdlfkdlfkdlfkd",
    "created_at": "2019-04-26T15:44:46.224Z",
    "updated_at": "2019-04-28T16:00:48.400Z",
    "__v": 0
  },

我已经尝试过像这样制作聚合管道

{
        $lookup: {
          from: "stores",
          localField: "store",
          foreignField: "_id",
          as: "store"
        }
      },
      {
        $lookup: {
          from: "products_comment",
          localField: "comment",
          foreignField: "_id",
          as: "comment"
        }
      },
      { $unwind: "$comment" },
      {
        $project: {
          media: 1,
          "store.type": 1,
          "store.profile.address.city": 1,
          "meta.title": 1,
          "meta.price": 1,
          "comment.rating": 1
        }
      }

但结果与预期不同，我想要这样的结果

 {
    "_id": "5cc570257631a313d489ba4a",
    "media": [
      "httpsdssd",
      "dfdfd"
    ],
    "comment": {
      1_rating: 0, <value of rating: count of value>
      2_rating: 3,
      3_rating: 5,
      ....,
    },
    "store": [
      {
        "type": "craft",
        "profile": {
            "address": {
               city: "Padang
            }
        }
      }
    ],
    "meta": {
      "title": "Traveling Sumbar",
      "price": "150000"
    }
  }

我该如何解决我的问题？

Answer 1

下面的查询将为您提供完全预期的输出:

var query = [
{
  $lookup: {
     from: "comments",
     localField: "comment",
     foreignField: "_id",
     as: "comments"
  }
},
{ $unwind: "$comments" },
{ $group : {
    _id: {
        _id: '$_id',
        rating: '$comments.rating',
        media : '$media',
        meta : '$meta',
        store : '$store'
    },
    totalRating: {$sum: 1}
 }
},
{
 $group : {
     _id : {
       _id : '$_id._id',
       media : '$_id.media',
       meta : '$_id.meta',
       store : '$_id.store'
     },
     comments : {
         $push : {
              rating : '$_id.rating',
              totalRating : '$totalRating'
          }
      }
 }
},
{
  $lookup: {
    from: "stores",
    localField: "store",
    foreignField: "_id",
    as: "store"
  }
},
{
   $project: {
        '_id' : '$_id._id',
        media : '$_id.media',
        store : '$store',
        meta : {
           title:  '$_id.meta.title',
           price : '$_id.meta.price'
        },
        comments : { "$arrayToObject": {
                    "$map": {
                        "input": "$comments",
                        "as": "el",
                        "in": {
                            "k": "$$el.rating",
                            "v": "$$el.totalRating"
                        }
                    }
                } 
        }
     }
 }
];

输出:

{
"_id" : ObjectId("5cc718715290f4ed550f5305"),
"media" : [
    "httpsdssd",
    "dfdfd"
],
"store" : [ ],
"meta" : {
    "title" : "Traveling Sumbar",
    "price" : "150000"
},
"comments" : {
    "3" : 1,
    "4" : 2
  }
}
{
   "_id" : ObjectId("5cc88d99d486568c5745e4b7"),
   "media" : [
        "maha",
        "sagar"
   ],
   "store" : [ ],
   "meta" : {
      "title" : "Sagar Sumbar",
       "price" : "15000"
    },
    "comments" : {
       "3" : 2,
       "5" : 1,
       "1" : 1
    }
  }

注意:商店数据将通过 $lookup 从商店集合中获取。我没有模型/数据，所以不在输出中。