我非常接近从这个查询中得到我想要的东西......但我只想要返回部分字段，而现在它却返回了所有字段。
注: 这是一个改进：我现在问的是如何归还 只在特定领域而我的类似 疑问 询问如何返回数据 起止日期之间
此外，请谁能提供一个答案，使用的是 MongoDB游乐场 与我的数据集，所以我可以尝试一下... ... 我不太明白如何给数据集 "命名"，使它们能在操场上工作!
const mongoose = require('mongoose');
const Schema = mongoose.Schema;
const RegisterSchema = new Schema({
userId: {type: Schema.Types.ObjectId, required: true},
accessToken: {type:String, required: true, default: null},
})
module.exports = Register = mongoose.model( 'register', RegisterSchema)
以下是一些寄存器数据
[
{
"_id": "5eac9e815fc57b07f5d0d29f",
"userId": "5ea108babb65b800172b11be",
"accessToken": "111"
},
{
"_id": "5ecaeba3c7b910d3276df839",
"userId": "5e6c2dddad72870c84f8476b",
"accessToken": "222"
}
]
下一个文档包含了与Register模式相关的数据，这些数据通过accessToken
const mongoose = require('mongoose');
const Schema = mongoose.Schema;
const NotificationSchema = new Schema({
accessToken: {type:String, required: true},
summaryId: {type:Number, required: true},
dateCreated: {type: Date, default: Date.now},
// I don't want these returned in the final results
dontWantThis1: {type:Number, required: true},
dontWantThis2: {type:Number, required: true},
})
module.exports = Notification = mongoose.model( 'notification', NotificationSchema)
以下是一些通知数据
[{
"_id": "5ebf0390c719e60004f42e74",
"accessToken": "111",
"summaryId": 1111,
"dontWantThis1": 61,
"dontWantThis2": 62,
"dateCreated": "2020-04-17T00:00:00.000+00:00" },
{
"_id": "6ebf0390c719e60004f42e76",
"accessToken": "222",
"summaryId": 2221,
"dontWantThis1": 71,
"dontWantThis2": 72,
"dateCreated": "2020-04-18T00:00:00.000+00:00" },
{
"_id": "6ebf0390c719e60004f42e78",
"accessToken": "111",
"summaryId": 1112,
"dontWantThis1": 611,
"dontWantThis2": 622,
"dateCreated": "2020-05-25T00:00:00.000+00:00" },
{
"_id": "6ebf0390c719e60004f42e80",
"accessToken": "222",
"summaryId": 2222,
"dontWantThis1": 711,
"dontWantThis2": 722,
"dateCreated": "2020-05-26T00:00:00.000+00:00" }
]
这段代码返回所有内容，包括'dontWantThis1'和'dontWantThis2'。
我不希望字段前缀为'dontWantThis'--但这只是为了显示我不想要的字段......。我并不是真的要排除前面带有'dontWantThis'的字段......它们可以被命名为'foo'或'apple'或'dog'，它们只是以这种方式命名来表明我不想要它们。
// make sure the input dates are REALLY date objects
// I only want to see notifications for the month of May (in this example)
var dateStart = new Date('2020-05-01T00:00:00.000+00:00');
var dateEnd = new Date('2020-05-30T00:00:00.000+00:00');
var match = {$match: { userId: mongoose.Types.ObjectId(userId) } };
var lookup ={
$lookup:
{
from: "my_Notifications",
localField: "accessToken",
foreignField: "accessToken",
as: "notifications"
}
};
var dateCondition = { $and: [
{ $gte: [ "$$item.dateCreated", dateStart ] },
{ $lte: [ "$$item.dateCreated", dateEnd ] }
]}
var project = {
$project: {
notifications: {
$filter: {
input: "$notifications",
as: "item",
cond: dateCondition
} } }
};
var agg = [
match,
lookup,
project
];
Register.aggregate(agg)
.then( ..... )
我想我可以做这样的事情，但它仍然返回所有的通知字段。
var project = {
$project: {
"_id": 1,
"userId": 1,
"accessToken":1,
"count":{$size:"$notifications"},
"notifications._id":1,
"notifications.summaryId": 1,
"notifications.dateCreated":1,
notifications : {
$filter: {
input: "$notifications",
as: "item",
cond: dateCondition
},
}}
};
我创建了另一个投影，并将其添加到管道中。
var project2 = {
$project: {
"_id": 1,
"userId": 1,
"accessToken":1,
"count":{$size:"$notifications"},
"notifications._id":1,
"notifications.summaryId": 1,
"notifications.dateCreated":1,
"notifications.dateProcessed":1,
}
};
var agg = [
match,
lookup,
project,
project2,
];
谢谢！ - 我非常接近得到我想要的查询结果...
https:/stackoverflow.comusers6635464ngshravil-py 是准确的。
我又创建了一个投影。
var project2 = {
$project: {
"_id": 1,
"userId": 1,
"accessToken":1,
"count":{$size:"$notifications"},
"notifications._id":1,
"notifications.summaryId": 1,
"notifications.dateCreated":1,
"notifications.dateProcessed":1,
}
};
然后把它添加到我的聚合管道中。
var agg = [
match,
lookup,
project,
project2,
];
成功了！-- 谢谢你 https:/stackoverflow.comusers6635464ngshravil-py。
你需要转换 notifications.dateCreated 到 ISODate，因为你的日期是字符串，通过使用 $dateFromString 和 $map 我建议你这样做，因为我不认为你可以用字符串格式做日期比较。另外，请确保 dateStart 和 dateEnd 也应在 ISODate 格式。
而你需要两个 $project 操作员，以实现这一目的。另外，我也没有看到任何字段带着 userAccessToken我想，它是 accessToken. 查看下面的查询。
db.Register.aggregate([
{
$lookup: {
from: "my_Notifications",
localField: "accessToken",
foreignField: "accessToken",
as: "notifications"
}
},
{
$project: {
"_id": 1,
"userId": 1,
"accessToken": 1,
notifications: {
$map: {
input: "$notifications",
as: "n",
in: {
"_id": "$$n._id",
"summaryId": "$$n.summaryId",
"dateCreated": {
$dateFromString: {
dateString: "$$n.dateCreated"
}
}
}
}
}
}
},
{
$project: {
"userId": 1,
"accessToken": 1,
"notifications": {
$filter: {
input: "$notifications",
as: "item",
cond: {
$and: [
{
$gte: [
"$$item.dateCreated",
ISODate("2020-05-24T00:00:00Z")
]
},
{
$lte: [
"$$item.dateCreated",
ISODate("2020-05-26T00:00:00Z")
]
}
]
}
}
}
}
},
{
$set: {
"count": {
$size: "$notifications"
}
}
}
])