Mongoose：$project return 中的 $sum 只有零

Question

我有一个查询使用 $lookup that "join" two models and $project to select all fields that i need only, and in that $project I need to $sum 一个名为 totalValue 的值，但只有 return 零：

我的查询

User.aggregate([{
      $match: {
        storeKey: req.body.store,
      }
    },
    {
      $group: {
        _id: {
          id: "$_id",
          name: "$name",
          cpf: "$cpf",      
          phone: "$phone",
          email: "$email",
          birthday: "$birthday",
          lastName: "$lastname"      
        },
        totalServices: {
          $sum: "$services"
        },    
      }
    },
    {
      $lookup: {
        from: "schedules",
        "let": { "id": "$_id.phone" },
        "pipeline": [
          { "$match": { "$expr": { "$eq": ["$customer.phone", "$$id"] }}},
          { "$project": { "scheduleStart": 1, "scheduleEnd": 1 }}
        ],
        "as": "user_detail"
      }  
    },  
    {
      $project: {
        _id: 1,
        name: 1,
        name: 1,
        cpf: 1,      
        phone: 1,
        email: 1,
        birthday: 1,
        totalServices: 1,
        totalValue: { $sum : "$user_detail.value" },   // here only return zero   
        count: {
          $sum: 1
        },
        user_detail: 1
      }
    },

Answer 1

您需要 $project user_details 投影中的 value 字段才能在下一个聚合阶段获得它

{ "$project": { "scheduleStart": 1, "scheduleEnd": 1, "value": 1 }}

Mongoose：$project return 中的 $sum 只有零

Mongoose: $sum in $project return only zero

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