Mongoose 自動遞增數組中的子文檔字段

Question

我正在將子文檔推送到一個數組：

const deliverySchema = new db.Schema({
  deliveryId: Number,
  amountDelivered: Number,
  price: Number
})

const suppliersSchema = new db.Schema({
  supplierName: String,
  phone:  Number,
  deliveries: [deliverySchema]
})

const delivery =  {
  "amountDelivered": 123,
  "price": 123
}

Suppliers.updateOne(
  { _id: supplierId },
  { $push: { deliveries: delivery } }
)

我怎樣才能讓該文檔中的deliveryId字段在更新時自動遞增。 所以結果看起來像：

{
  "supplierName": "Test supplier",
  "phone": 12345678,
  "deliveries": [
    {
      "deliveryId": 1, // Auto increment this field on update
      "amountDelivered": 123,
      "price": 123
    },
    {
      "deliverId": 2,
      "amountDelivered": 123,
      "price": 1234
    }
  ]
}

Answer 1

您可以使用聚合框架來做到這一點：

• $concatArrays - 將當前交付數組與新項目連接起來
• $size - 獲取交付數組的當前大小
• $sum -將 deliveries數組的當前大小與 1 相加並使用結果來設置deliveryId

db.collection.update({
  "key": 1
},
[
  {
    "$set": {
      "deliveries": {
        "$concatArrays": [
          "$deliveries",
          [
            {
              "deliveryId": {
                "$sum": [
                  1,
                  {
                    "$size": "$deliveries"
                  }
                ]
              },
              "amountDelivered": 123,
              "price": 123
            }
          ]
        ]
      }
    }
  }
])

工作示例