汇总$ lookup不会返回所有记录

Question

我的Node.js应用程序中具有以下架构：

let CategorySchema = mongoose.Schema({        
    name: { type: String, required: true }
});

let UserSchema = mongoose.Schema({
        firstName: { type: String, required: true },
        lastName: { type: String, required: true }
});

let CustomerSchema = mongoose.Schema({        
    name: { type: String, required: true }
});

let VendorSchema = mongoose.Schema({
    userID: { type: mongoose.Schema.Types.ObjectId, ref: 'User' },
    category: [{ type: mongoose.Schema.Types.ObjectId, ref: 'Category' }],
    products: [ { type: mongoose.Schema.Types.ObjectId, ref: 'Product' } ],
    name: { type: String, required: true }
});

let ProductSchema = mongoose.Schema({        
        vendorID: { type: mongoose.Schema.Types.ObjectId, ref: 'Vendor' },
        name: { type: String, index: true, required: true },      
        customerReviews: [{
            stars: { type: Number, required: false },
            review: { type: String, required: false },
            customerId: { type: mongoose.Schema.Types.ObjectId, ref: 'Customer', required: true }
        }]
});

并且我正在尝试查询Vendors集合以返回以下结果：

{
    _id: "dsi9dsik129dkdsdsds",
    userData: {
      _id: "dsa9dskd2kwd29dkkss",
      firstName: "Michael",
      lastName: "White"
    },
    categoryData: {
      _id: "e9dids91i239dskds91",
      name: "Category A"
    },
    productsData: [ {
      _id: "3132139i31j32131",
      vendorID: "dsi9dsik129dkdsdsds",
      name: "Product ABC",
      customerReviews [{
          stars: "5",
            review: "Good",
          customerData: {
            _id: "zds91i232131j2321j",
            name: "John silver"
          }
      },
      {
        stars: "3",
            review: "Bad",
        customerData: {
        _id: "ldso91232131j2321j",
        name: "Mark Spenser"
        }
      }],
      avgRating: 4
    },
    {
      _id: "3132139i31ds9daskd",
      vendorID: "dsi9dsik129dkdsdsds",
      name: "XYZ",
      customerReviews [{
          stars: "2",
            review: "bad",
          customerData: {
            _id: "zds91i23212019329",
            name: "Michael Smith"
          }
      },
      {
        stars: "5",
            review: "Perfect",
        customerData: {
        _id: "ldso91232131ds9911",
        name: "Mary"
        }
      }],
      avgRating: 3.5
    } ],
    name: "Vendor XYZ"
}

基于此处的较早答案，我在对其进行一些修改以包含平均评分之后使用了以下汇总查询，但不幸的是，它将始终仅从供应商数据产品数组中返回一种产品，并且会合并该产品中所有产品的评论单个产品退回，所以我想知道是否有人可以提供帮助并告诉我在这里我可能会缺少什么/做错了什么？

{"$lookup":{ 
    "from": "users", 
    "localField": "userID", 
    "foreignField": "_id",
    "as": "userData"  
}},
{"$unwind":"$userData"},
{"$lookup":{ 
    "from": "categories", 
    "localField": "category", 
    "foreignField": "_id",
    "as": "categoryData"  
}},
{"$lookup":{ 
   "from":"products",
   "let":{"products":"$products"},
   "pipeline":[
     {"$match":{"$expr":{"$in":["$_id","$$products"]}}},
     {"$unwind":{"path":"$customerReviews", "preserveNullAndEmptyArrays":true}},         
     {"$lookup":{
      "from":"customers",
      "localField":"customerReviews.customerId",
      "foreignField":"_id",
      "as":"customerData"
     }},
    {"$unwind":{"path":"$customerData", "preserveNullAndEmptyArrays":true}}, 
    {"$group":{
      "_id":"$_id",
      "vendorID": {"$first":"$vendorID"},
      "name": {"$first":"$name"},
      "customerReviews":{
         "$push":{ 
           "stars": "$customerReviews.stars",
           "review": "$customerReviews.review",
           "customerData":"$customerData"
          }
        }
     }},
    { $addFields: { avgRating: { $avg: '$customerReviews.stars' } } }       
  ],
  "as":"productsData"
}}

样本数据：

Category:
{
    "_id" : ObjectId("5de7fc530ce9d05be4024170"),
    "categoryName" : "Glass",
    "__v" : 0
}

User:
{
    "_id" : ObjectId("5d6671ae7be3be4e18ebe9bb"),
    "firstName" : "Mark",
    "lastName" : "Smith",
    "__v" : 0
}

Customer:
{
    "_id" : ObjectId("5dd7cb11f4b2544253368f24"),
    "customerName" : "Michael White",
    "__v" : 0
},
{
    "_id" : ObjectId("5dd7cb11f4b2544253372e33"),
    "customerName" : "Mary",
    "__v" : 0
}

Vendor:
{
    "_id" : ObjectId("5de7fc6a0ce9d05be4024171"),
    "category" : [ 
        ObjectId("5de7fc530ce9d05be4024170")
    ],
    "products" : [ 
        ObjectId("5de8474ccd0bbc05256db819"), ObjectId("5de8474ccd0bbc05255eq323")
    ],
    "userID" : ObjectId("5d6671ae7be3be4e18ebe9bb"),
    "vendorName" : "Michael White",
    "__v" : 0
}

Product:
{
    "_id" : ObjectId("5de8474ccd0bbc05256db819"),
    "vendorID" : ObjectId("5de7fc6a0ce9d05be4024171"),
    "name" : "Red Sause",
    "customerReviews" : [ 
        {
            "moderated" : false,
            "_id" : ObjectId("5de7fcf20ce9d05be4024175"),
            "customerId" : ObjectId("5dd7cb11f4b2544253368f24"),
            "stars" : 3,
            "review" : "Didn't like it that much :( ",
            "date" : ISODate("2019-12-04T18:37:38.253Z")
        }
    ],
    "__v" : 0
},
{
    "_id" : ObjectId("5de8474ccd0bbc05255eq323"),
    "vendorID" : ObjectId("5de7fc6a0ce9d05be4024171"),
    "name" : "Cups",
    "customerReviews" : [ 
        {
            "moderated" : false,
            "_id" : ObjectId("5de7fcf20ce9d05be4021111"),
            "customerId" : ObjectId("5dd7cb11f4b2544253368f24"),
            "stars" : 5,
            "review" : "Excellent ",
            "date" : ISODate("2019-12-04T18:37:38.253Z")
        },
        {
            "moderated" : true,
            "_id" : ObjectId("5de7fcf20ce9d05be4022222"),
            "customerId" : ObjectId("5dd7cb11f4b2544253372e33"),
            "stars" : 4,
            "review" : "Good ",
            "date" : ISODate("2019-12-04T18:37:38.253Z")
        }
    ],
    "__v" : 0
}