Mongoose GroupBy 与 Populate

Question

我有用户文档和与商店文档相关的类别文档，看起来像

  var ShopSchema = mongoose.Schema(
  {
    shopName: {
      type: String,
      required: [true, 'A Shop must have name'],
    },
    phone: {
        type: String,
        validate: [validator.isMobilePhone,"Phone number is not a valid number"],
        required: [true, 'A Shop must have hepline number'],
    },
    shopStatus: {
        type: Boolean,
        default: false,
        select: false
    },
    managerId:{
        type: mongoose.Schema.ObjectId,
        ref:'User',
        require: [true,'Shop must have to a manager!']
    },
    createdAt:{
        type:Date,
        default: Date.now()
    },
    shopCategory:{
        type: mongoose.Schema.ObjectId,
        ref:'Category',
        require: [true,'Shop must have a Category!']
    },

  },
  {
    toJSON: { virtuals: true },
    toObject: { virtuals: true }
  }
);

const Shop = mongoose.model("Shop", ShopSchema);
  

现在我正在编写一个查询来获取经理商店（groupBy managerId），其中包含经理和类别数据。但我每次都得到空数组。

 const doc = await Shop.aggregate([
        { 
            $match: { shopStatus: {$ne: false} } 
        },
        { 
            $group: {
                _id:'$managerId',
                numofShop: {$sum: 1},
                shopCategory: {$first: "$shopCategory"}
            }
        },
        { 
            $lookup: {
               from: "User",
               localField : "_id",
               foreignField: "_id",
               as: "Manager"
             }
       },
       { 
            $lookup: {
                from: "Category",
                localField : "shopCategory",
                foreignField: "_id",
                as: "Category"
            }
       },
     ])

这是我的最终结果，但这是一个空数组。

        {
            "_id": "5f467660f630e804ec07fad8",
            "numofShop": 2,
            "Manager": [],
            "Category": []
        },
        {
            "_id": "5f44d2f4ff04993b40684bf9",
            "numofShop": 1,
            "Manager": [],
            "Category": []
        }

我想查找所有商店 groupBy managerId（谁拥有它）。 managerId 的字段引用了创建此商店的用户文档。我想要这样的数据

    {
        "_id": "5f44d2f4ff04993b40684bf9",
        "Manager": {},//this is populated through User Schema
        "numofShop": 1,
        "Shop": [
                  { 
                     "shopName":"Grocery Shop",
                     "phone" : "111111",
                     "shopCategory" :{"_id": "","name":"Electronics"}
                  }
                ]
    }
    .....
    .....

在此处查找示例数据 商店-http://txt.do/1fwi0 两个用户创建的 3 个商店 用户 - http://txt.do/1fwio 分类-http://txt.do/1fwij

Answer 1

有 2 个修复，

• 在第二次查找中，您在 localField 中没有 shopCategory 字段，因为您尚未在 $group 中定义 shopCategory，

{ 
  $group: {
    _id:'$managerId',
    numofShop: {$sum: 1},
    shopCategory: { $first: "$shopCategory" } // define here
  }
},

• 在第一次查找用户集合时，没有managerId字段并且您已在_id字段中分配，那么您可以在localField中使用_id，

{
  $lookup: {
    from: "User",
    localField : "_id", // change this from managerId
    foreignField: "_id",
    as: "Manager"
  }
},

更新问题后更新的东西，Playground1，Playground2

---

对于您的第二次编辑，您不能将填充条件放入 find 方法中，如何将条件放入填充中，您可以按照 answer1 和 answer2 进行操作