Mode 1: mongod Command Mode 2: brew services start mongodb Command start what s the difference between the two ways of starting? why are there two ways? ...

encountered a small problem when practicing: videouseruseriduseridavatar,videouser: then res.send () will execute before User.findOne () . how can I execute res.send () after User.findOne () ? the newcomer at the front end understands Pr...

const MongoClient = require( mongodb ).MongoClient; const url = mongodb: localhost:27017 ; Database Name const dbName = youyue ; var obj = {}; module.exports = async(ctx,next)=>{ const num = ctx.query.num, page = ctx.query.pag...

Collection a has the following documents: { "_id" : ObjectId("5acd77c763c9b117b48b2e92"), "Symbol" : "item01", "min5" : [ { "Symbol" : "item01", ...

router.get( VaguePartner , function (req, res, next) { const keyWords = req.query.keyWords t_Superior.find().populate( consumer firstsuperior ).where( consumer ).or([ { nickname : { $regex : keyWords, $options: $i } }, ...

after logging in to mongodb show collections2 db.system.users.find() : db.system.users.remove({user: "bear "}) : now if you want to delete this right, what should I do?! Ask for advice ...

has the following two Model (1) user Model var usersSchema = new Schema({ f_id: { unique: true, type: String }, f_name: String }) (2) record Model var batchMainSchema = new Schema({ f_id: { unique: tr...

ask for methods or tools for importing excel into MongoDB database it s better to have tutorials or blog links Thank you ...

for example, if there is a relationship between an article and a tag, an article (page) has multiple tags (tag), and a tag (tag) can be shared by multiple article (page) < H2 > get the page list, hope to get the corresponding tag, then get the tag list...

my node project turned out to be good, but then I didn t remember what I did to load the mongodb dependency and reported it wrong just this sentence var MongoClient = require ( mongodb ). MongoClient; reported error: exception: Error Error: EN...

encountered a problem when trying to tamper with a forum with express+mongoose to implement the comment function. model: of the post const ArticleSchema = new Schema({ author: { type: Schema.Types.ObjectId, ref: "User" }, createTime: { ...

mongodb version is ^ 3.0.9 ...

personal blog A personal blog written by has a concurrency problem: using Aliyun s pts to test concurrency, it is found that when the number of concurrency reaches 8 (which is negligible), the database query is particularly slow (there is very littl...

new Schema({ pid: {type: String, ref: product }, sid: {type: String, ref: sale }, })); suppose there are product and sale two collections pid and sid both specify user_id of the product and sale collections instead of _ id ...

the general situation is about the same as this https: cnodejs.org topic 50d. schema: const userInfoSchema = new Schema({ uId: String, userId: Number, wxInfo: { unionid: String, openid: String, nickName: String, avatarUrl: Stri...

problem description word files accessed by mongodb need to be displayed in the browser, but the browser is not good at displaying office files, so the current solution is to read word, through gridfs-stream in the background and then convert it to pdf...

now there are such data structures, such as in the collection class. { _id:ObjectId123456789...), number:10, students:[ { studentId:ObjectId(123456789...) * studentid * }, ...

for example: my backend model defines an object, user = { name: required false, mobile: required true, email: required false } since my name field and email field are not required, I did not send it at the front end, but passed json: in the fo...

for example const ProjectSchema = new mongoose.Schema ({) name : { type:String }, time : { type:Date, default:Date.now }, url : { type: String}, user : { type: Object}, proId : {type: String}, spaceId : {type: String}, description: {type: String...

WeChat Pay document mentioned: before checking and processing business data, data locks should be used for concurrency control. In order to avoid data confusion caused by function reentry, the Wechat server notifies the same payment result with a frequen...