1.操作Mongo的Array
https://docs.mongodb.com/manual/reference/operator/update/pull/#up._S_pull
Ex: 以下可把rating_my Array中的item物件中的_id與req.body.item._id
值相同的所有欄位移除
Copy User.update({_id: req.token.data._id}, {$pull: { //先把舊的移除
rating_my: {
"item._id": req.body.item._id
}
}})
2.分頁快速query
http://stackoverflow.com/questions/7228169/slow-pagination-over-tons-of-records-in-mongo
3.使用Geo search
https://docs.mongodb.com/manual/reference/operator/query-geospatial/
以下使用$near為範例
1.先在schema建立index
Copy var c = new mongoose.Schema({
status: String, //物品承租階段狀態 eg,尋租中,已出租,已還租
rented: Boolean, //是否已出租
renterInfo: Object, //承租者相關資訊,填表
lessee: String, //承租者
geometry: {
type: {
type: String,
default: "Point"
},
coordinates: [Number]
}, //物品所在地
regionName: String,
})
c.index({geometry: '2dsphere'});
exports.Test = mongoose.model('test', c)
建立後可以查看到index
2.之後即可搜尋
Copy Test.find({geometry:
{ $near :
{
$geometry: {type : "Point", coordinates: [ -149.0133, 64.7440 ] },
$minDistance: 0,
$maxDistance: 50
}
}})
.then(data => {
//console.log(data)
res.end(JSON.stringify(data))
})
.catch(err => {
console.log(err);
res.end(err.toString());
})
3.另外要記得coordinates 是先放Longitude才放Latitude,跟一般google地圖相反
Copy $minDistance: 0,
$maxDistance: 50
單位為公尺
4.新增欄位
新增欄位的意思為在每個document新增一筆資料。
Copy db.your_collection.update(
{},
{ $set: {"new_field": 1} },
false,
true
)
後面兩個參數分別為:
Copy Upsert: If set to true, creates a new document when no document matches the query criteria.
Multi: If set to true, updates multiple documents that meet the query criteria. If set to false, updates one document.
https://stackoverflow.com/a/7714428
5.刪除 DB 資料
Copy use DB名稱
db.dropDatabase();
不會刪除 DB內的 USER
6. Aggregate
用來進階版 query 資料的方法,可組合出許多進階技。
範例: 取得某段時間內的資料累計 (範例資料以小時為單位)
Copy const { MongoClient } = require("mongodb");
const marketcap = require("./marketcap-data.js");
// Replace the uri string with your MongoDB deployment's connection string.
const uri = "mongodb://root:example@localhost:27017";
const client = new MongoClient(uri);
async function queryMarketCapData() {
try {
await client.connect();
const database = client.db("...");
const marketcapCollection = database.collection("market-cap");
const pipeline = [
{
$group: {
_id: { // 取得月度資料累計
year: { $year: "$timestamp" },
//week: { $week: "$timestamp" },
month: { $month: "$timestamp" },
//dayOfYear: { $dayOfYear: "$timestamp" },
},
value: { $sum: "$value" },
},
},
{
{
$sort: { "_id": 1 },
}
}
];
const aggCursor = marketcapCollection.aggregate(pipeline);
for await (const doc of aggCursor) {
console.log(doc);
}
} catch (err) {
console.log(err);
}
}
queryMarketCapData();
三個月為一組資料加總
Copy const pipeline = [
{
$group: {
_id: {
year: { $year: "$timestamp" },
month: {
$subtract: [
{ $month: "$timestamp" },
{ $mod: [{ $month: "$timestamp" }, 3] },
],
},
},
value: { $sum: "$value" },
},
},
{
$sort: { _id: 1 },
},
];