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What is the difference in the way mongodb starts?
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?
...
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Database nested query, how to solve the asynchronous problem.
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...
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Koa2 uses mongodb to write api interface to get data, how to get data elegantly (I am adding data to a new object, it's too low)
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...
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How does mongdb manipulate subdocument arrays (query and return subarrays, add or modify specified index entries)?
Collection a has the following documents:
{
"_id" : ObjectId("5acd77c763c9b117b48b2e92"),
"Symbol" : "item01",
"min5" : [
{
"Symbol" : "item01",
...
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How does mongoose query based on join table fields or virtual fields?
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 } },
...
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How to delete the right information of the database after the establishment of the right in mongoDB?
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
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Populate nesting usage of mongodb
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...
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The method of how to import excel into MongoDB database
ask for methods or tools for importing excel into MongoDB database it s better to have tutorials or blog links Thank you ...
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How to design n-to-n MongoDB database
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...
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Implementation of nodejs Project comment function
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: { ...
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The BSONPure module cannot be found in node's mongodb package.
mongodb version is ^ 3.0.9
...
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The efficiency of mongodb concurrent query is very low.
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...
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[mongoose] how does populate relate to a non-_ id field?
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
...
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How to modify only a few value? of object by mongoose
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...
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How to convert word streams read by gridfs-stream to pdf
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...
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Mongodb's associated query $lookup
now there are such data structures, such as in the collection class.
{
_id:ObjectId123456789...),
number:10,
students:[
{
studentId:ObjectId(123456789...) * studentid *
},
...
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How does Mongodb save data to ensure the integrity of fields?
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...
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How does mongoose find a value in an array?
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...
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How does nodejs use mongoose to connect remotely to mongo on centos
read the official code mongoose.connect ( mongodb: username:password@host:port database?options. );
and then it can t be connected at all. That s what I wrote .
mongoose.connect ( mongodb: root:123456@1,2,3,4:66 );
is there a great god who...
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How does mongodb handle concurrent requests?
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...
