我正在尝试从 mongodb 获取数据,但没有得到预期的输出
I am trying to get retrive data from mongodb but not getting expected output
数据库数据-
[{
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
}]
预期输出:
[{
category: "mobile",
qty: 2,
totalAmount: 53000
},
{
category: "laptop",
qty: 2,
totalAmount: 200000
}]
代码我是运行(使用mongoose)
let products = await Product.aggregate([
{
$project: { _id: 0, category: 1, amount: 1 },
},
{
$group: {
_id: "$category",
qty: { $sum: 1 },
totalAmount: { $sum: "$amount" },
},
},
]);
我得到的结果。
[
{
"_id": "laptop",
"count": 2,
"totalSum": 200000
},
{
"_id": "mobile",
"count": 2,
"totalSum": 53000
}
]
你可以清楚地看到我能够获得正确的数据,但我想要正确的名称和类别而不是 _id。请帮助我。提前致谢
您需要$project
作为最后阶段来修饰输出文档。
{
$project: {
_id: 0,
category: "$_id",
qty: "$qty",
totalAmount: "$totalAmount"
}
}
同时,第一阶段$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"
}
}
])
您可以使用以下查询来获得预期的输出。干杯~
await Product.aggregate([
{
$group: {
_id: "$category",
qty: {
$sum: 1
},
totalAmount: {
$sum: "$amount"
},
},
},
{
$addFields: {
category: "$_id"
}
},
{
$project: {
_id: 0
},
}
])
数据库数据-
[{
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
}]
预期输出:
[{
category: "mobile",
qty: 2,
totalAmount: 53000
},
{
category: "laptop",
qty: 2,
totalAmount: 200000
}]
代码我是运行(使用mongoose)
let products = await Product.aggregate([
{
$project: { _id: 0, category: 1, amount: 1 },
},
{
$group: {
_id: "$category",
qty: { $sum: 1 },
totalAmount: { $sum: "$amount" },
},
},
]);
我得到的结果。
[
{
"_id": "laptop",
"count": 2,
"totalSum": 200000
},
{
"_id": "mobile",
"count": 2,
"totalSum": 53000
}
]
你可以清楚地看到我能够获得正确的数据,但我想要正确的名称和类别而不是 _id。请帮助我。提前致谢
您需要$project
作为最后阶段来修饰输出文档。
{
$project: {
_id: 0,
category: "$_id",
qty: "$qty",
totalAmount: "$totalAmount"
}
}
同时,第一阶段$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"
}
}
])
您可以使用以下查询来获得预期的输出。干杯~
await Product.aggregate([
{
$group: {
_id: "$category",
qty: {
$sum: 1
},
totalAmount: {
$sum: "$amount"
},
},
},
{
$addFields: {
category: "$_id"
}
},
{
$project: {
_id: 0
},
}
])