我有一个聚合管道，应该返回一个有序数组。然而。每次我进行API校准时，每次都会返回不同的顺序。这是我的代码
exports.getResultToCompetition = asyncHandler(async (req, res, next) => {
const data = await Result.aggregate([
{
$match: { competition: mongoose.Types.ObjectId(req.params.competitionId) },
},
{
$project: {
points: 1,
kilogramms: 1,
sector: 1,
user: 1,
competition: 1,
place: 1,
},
},
{
$sort: {
kilogramms: -1,
},
},
{
$lookup: {
from: "users", // must be the PHYSICAL name of the collection
localField: "user",
foreignField: "_id",
as: "user",
},
},
{
$addFields: {
user: {
$arrayElemAt: ["$user", 0],
},
},
},
{
$group: {
_id: "$sector",
res: {
$push: "$$ROOT",
},
},
},
]);
res.status(200).json({ success: true, data });
});
和模式：
const mongoose = require('mongoose');
const ResultSchema = new mongoose.Schema({
competitionSeries: {
type: String,
default: 0,
},
points: {
type: Number,
default: 0,
},
sector: {
type: String,
},
kilogramms: {
type: Number,
default: 0,
},
place: {
type: Number,
default: 0,
},
isCompetitionRunning: {
type: Boolean,
default: true,
},
user: {
type: mongoose.Schema.Types.ObjectId,
ref: 'User',
required: true,
},
team: {
name: {
type: mongoose.Schema.Types.ObjectId,
ref: 'User',
},
partner: {
type: String,
},
teamName: {
type: String,
},
},
competition: {
type: mongoose.Schema.Types.ObjectId,
ref: 'Competition',
required: true,
},
});
module.exports = Result = mongoose.model('Result', ResultSchema);
千克字段在MongoDB数据库中另存为Double 我在React的前端将值设置为数字。 我不确定是否导致问题。 公斤值应该是浮点数，例如14.5
这是正确的结果：
{
"success": true,
"data": [
{
"_id": "B",
"res": [
{
"_id": "5eca12e2607c2c0017c16904",
"points": 1,
"kilogramms": 90.52,
"place": 59,
"sector": "B",
"competition": "5eb90caa7b45620017a4d919",
"user": {
"_id": "5eb82c89e5d6cc0017e71a2a",
"avatar": "placeholder.jpg",
"role": "user"
}
},
{
"_id": "5eca1406607c2c0017c16918",
"points": 2,
"kilogramms": 39.45,
"place": 10,
"sector": "B",
"competition": "5eb90caa7b45620017a4d919",
"user": {
"_id": "5eb83175e5d6cc0017e71a42",
"avatar": "653571a228226499806e8a717cf2d6e1",
"role": "user"
}
},
{
"_id": "5eca11fc607c2c0017c168f5",
"points": 3,
"kilogramms": 29.62,
"place": 8,
"sector": "B",
"competition": "5eb90caa7b45620017a4d919",
"user": {
"_id": "5eb83970e5d6cc0017e71a64",
"avatar": "1589316331809-feederuser",
"role": "user"
}
},
{
"_id": "5eca1250607c2c0017c168fa",
"points": 4,
"kilogramms": 24.25,
"place": 56,
"sector": "B",
"competition": "5eb90caa7b45620017a4d919",
"user": {
"_id": "5eb83a00e5d6cc0017e71a67",
"avatar": "placeholder.jpg",
"role": "user"
}
}
]
},
{
"_id": "C",
"res": [
{
"_id": "5eca12cc607c2c0017c16903",
"points": 1,
"kilogramms": 72.43,
"place": 52,
"sector": "C",
"competition": "5eb90caa7b45620017a4d919",
"user": {
"_id": "5eb83c2ee5d6cc0017e71a70",
"avatar": "56065850e67a64878e5034d06cecc0ea",
"role": "user"
}
},
{
"_id": "5eca1307607c2c0017c16907",
"points": 2,
"kilogramms": 43.35,
"place": 12,
"sector": "C",
"competition": "5eb90caa7b45620017a4d919",
"user": {
"_id": "5eb998864d62090017231ce6",
"avatar": "placeholder.jpg",
"role": "user",
"name": "Halász Tibor"
}
},
{
"_id": "5eca1325607c2c0017c16909",
"points": 3,
"kilogramms": 39.43,
"place": 15,
"sector": "C",
"competition": "5eb90caa7b45620017a4d919",
"user": {
"_id": "5eb9b46c4d62090017231cf8",
"avatar": "placeholder.jpg",
"role": "user"
}
},
{
"_id": "5eca14c1607c2c0017c16927",
"points": 4,
"kilogramms": 36.99,
"place": 11,
"sector": "C",
"competition": "5eb90caa7b45620017a4d919",
"user": {
"_id": "5eb82fdbe5d6cc0017e71a3d",
"avatar": "placeholder.jpg",
"role": "user"
}
}
]
}
]
}
再次调用端点后，它显示了不同的顺序。意思是，C区排在第一位，这是不正确的，因为B区的公斤数更高。
答案 0 :(得分：1)
您可以在文档中添加maxKilogramm字段，并通过在聚合末尾添加以下阶段来对该字段进行排序。
{
$addFields: {
"maxKilogramm": {
$max: "$res.kilogramms"
}
}
},
{
$sort: {
maxKilogramm: -1,
},
},
{
$project: {
maxKilogramm: 0
}
}