資料庫資料 -
[{
title: "Vivo X50",
category: "mobile",
amount: 35000
},
{
title: "Samsung M32",
category: "mobile",
amount: 18000
},
{
title: "Lenovo 15E253",
category: "laptop",
amount: 85000
},
{
title: "Dell XPS 15R",
category: "laptop",
amount: 115000
}]
預期輸出：
[{
category: "mobile",
qty: 2,
totalAmount: 53000
},
{
category: "laptop",
qty: 2,
totalAmount: 200000
}]
我正在運行的代碼（使用貓鼬）
let products = await Product.aggregate([
{
$project: { _id: 0, category: 1, amount: 1 },
},
{
$group: {
_id: "$category",
qty: { $sum: 1 },
totalAmount: { $sum: "$amount" },
},
},
]);
結果我得到了。
[
{
"_id": "laptop",
"count": 2,
"totalSum": 200000
},
{
"_id": "mobile",
"count": 2,
"totalSum": 53000
}
]
正如您可以清楚地看到我能夠獲得正確的資料，但我也想要正確的名稱類別而不是_id。請幫幫我。提前致謝
uj5u.com熱心網友回復：
您需要$project作為裝飾輸出檔案的最后階段。
{
$project: {
_id: 0,
category: "$_id",
qty: "$qty",
totalAmount: "$totalAmount"
}
}
同時，第一階段$project不需要。
db.collection.aggregate([
{
$group: {
_id: "$category",
qty: {
$sum: 1
},
totalAmount: {
$sum: "$amount"
}
}
},
{
$project: {
_id: 0,
category: "$_id",
qty: "$qty",
totalAmount: "$totalAmount"
}
}
])
示例 Mongo Playground
uj5u.com熱心網友回復：
您可以使用以下查詢來獲得預期的輸出。干杯~
await Product.aggregate([
{
$group: {
_id: "$category",
qty: {
$sum: 1
},
totalAmount: {
$sum: "$amount"
},
},
},
{
$addFields: {
category: "$_id"
}
},
{
$project: {
_id: 0
},
}
])轉載請註明出處，本文鏈接：https://www.uj5u.com/gongcheng/424003.html
標籤：节点.js mongodb 猫鼬 mongodb查询 聚合框架