How to build a query server in express-JS Tutorial-php.cn

How to build a query server in express

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Release： 2018-04-12 17:33:32

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This time I will bring you how to build a query server with express. What are the precautions for express to build a query server? The following is a practical case, let’s take a look.

This article introduces the method of using express to build a simple query server and shares it with everyone. The details are as follows:

The technology stacks used include express and mysql.

Project structure:

service
--node_modules
--app.js
--query.js

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app.js supports calling services and using body-parser to process requests.

query.js implements the functions of linking to the database and querying the database.

The app.js code is as follows:

var express = require('express');
var query = require('./query')
var bodyParser = require('body-parser');
var cookieParser = require('cookie-parser');
var app = express();
app.use(bodyParser.urlencoded({ extended: false }))//返回的对象是一个键值对，当extended为false的时候，键值对中的值就为'String'或'Array'形式，为true的时候，则可为任何数据类型。
app.use(bodyParser.json())
//跨域支持
app.all('*', function(req, res, next) {
  res.header("Access-Control-Allow-Origin", "*");
  res.header('Access-Control-Allow-Methods', 'PUT, GET, POST, DELETE, OPTIONS');
  res.header("Access-Control-Allow-Headers", "X-Requested-With");
  res.header('Access-Control-Allow-Headers', 'Content-Type');
  next();
});
//登录
app.post('/login',(req,res)=>{
  var opts = req.body;
  query(" SELECT *FROM `v_users` WHERE userAcount = ?",opts.userName).then((result)=>{
    var response = result[0];
    if(opts.password !== response.u_password){
      return res.send({
        errorCode:'404',
        errorMsg:'登录密码错误'
      })
    }
    //模拟生成loginToken
    var loginToken = response.userAcount + Math.random()*Math.pow(10,16)
    res.send({
      loginToken:loginToken
    })
  })
})
var server = app.listen(3000,()=>{
  console.log('success')
})

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The query.js code is as follows:

(function() {
  var mysql = require('mysql');
  // var session = require('cookie-session');
  var query = (sql,key) => {
    var connection = mysql.createConnection({
      host: 'localhost',
      user: 'root',
      password: 'root123',
      database: 'm_users'
    });
    connection.connect()
    var promise = new Promise((resolve,reject)=>{
      connection.query(sql,[key], function(error, results, fields) {
        if(error){
          reject(error)
        }else{
          resolve(results);
        }
      });
      connection.end();
    });
    return promise;
  }
  module.exports = query;
})()

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Practice summary:

1. Entry-level usage of express, as well as usage of body-parser and mysql plug-ins.

2. Try to use Inspector to debugnode program and implement debugger, by the way. I am more accustomed to using gulp for debugging.

3.When the client uses post to call the interface, it must distinguish the difference of Content-Type:

Content-Type:application/json;charset=UTF-8 parameter is placed in requestPayload

Content-Type: is not set or application/x-www-form-urlencoded parameter is placed in Form Data

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website!