Home>Article>Web Front-end> Let’s talk about get/post requests and middleware in nodejs
This article will take you through hot restart, get request, post request and middleware innode.js. I hope it will be helpful to everyone!
1. Installation
npm i nodemon
2. Run and start
nodemon .bin/www
http://localhost:8080/login?goods1=0001&goods2=0002
nodeoperation.
If the response is:http://localhost:8080/login?goods1=0001&goods2=0002then Pass:
req.queryHe will get all the data, or
req.query.goods1 req.query.goods2to separate or remove each data. In short, different needs correspond to different businesses, and everyone can obtain it according to their own needs;
node:
const express = require("express"); var app = express(); app.get("/",function(req,res){ res.send("主页"); }); app.get("/login",function(req,res){ console.log(req.query); res.send("登录路由,user为:"+req.query.user+"==> password为:"+req.query.password); }); app.listen(8080);
enctypeattribute Generally set to "
application/x-www-form-urlencoded", if set to
multipart/form-data, it is mostly used for file upload, as follows:
app.use(express.urlencoded())3. Get body data
req.body.username
APP.JSDocument 登陆
var express = require('express'); var path = require('path') var app = express(); var sqlQuery = require('./lcMysql') // view engine setup app.set('views', path.join(__dirname, 'views')); app.set('view engine', 'ejs'); app.use(express.static(path.join(__dirname, 'public'))); //解析post提交的数据 app.use(express.urlencoded()) //搜索首页 app.get('/',(req,res)=>{ res.render('index.ejs') }) //登陆页 app.get('/login',(req,res)=>{ res.render('login') }) //处理登陆请求 app.post('/login',async (req,res)=>{ //获取用户名和密码 let username = req.body.username let password = req.body.password //查询数据库是否由此用户名和密码 let sqlStr = 'select * from user where username = ? and password = ?'; let arr = [username,password]; let result = await sqlQuery(sqlStr,arr) if(result.length == 0 ){ res.send("登陆失败") }else{ res.send("登陆成功") } }) module.exports = app;
const express=require("express"); var app=express(); //匹配路由之前的操作 app.use(function(req,res,next()){ console.log("访问之前"); }); app.get("/",function(req,res){ res.send("主页"); }); app.listen(8080);At this time we will find that the
const express=require("express"); var app=express(); //匹配路由之前的操作 app.use(function(req,res,next){ console.log("访问之前"); next(); }); app.get("/",function(req,res){ res.send("主页"); }); app.listen(8080);Of course, you can also simplify the writing:
const express=require("express"); var app=express(); app.use(function(req,res,next){ console.log("访问之前"); next(); },function(req,res){ res.send("主页"); }); app.listen(8080);Therefore, when performing route matching If you want to perform an operation before or after recording and continue to execute, application layer middleware is undoubtedly a good choice.
路由级中间件和应用级中间件类似,只不过他需要绑定express.Router();
var router = express.Router()
在匹配路由时,我们使用 router.use() 或 router.VERB() ,路由中间件结合多次callback可用于用户登录及用户状态检测。
const express = require("express"); var app = express(); var router=express.Router(); router.use("/",function(req,res,next){ console.log("匹配前"); next(); }); router.use("/user",function(req,res,next){ console.log("匹配地址:",req.originalUrl); next(); },function(req,res){ res.send("用户登录"); }); app.use("/",router); app.listen(8080);
总之在检测用户登录和引导用户应该访问哪个页面是,路由中间件绝对好用。
顾名思义,它是指当我们匹配不到路由时所执行的操作。错误处理中间件和其他中间件基本一样,只不过其需要开发者提供4个自变量参数。
app.use((err, req, res, next) => { res.sendStatus(err.httpStatusCode).json(err); });
一般情况下,我们把错误处理放在最下面,这样我们即可对错误进行集中处理。
const express=require("express"); var app=express(); app.get("/",function(req,res,next){ const err=new Error('Not Found'); res.send("主页"); next(err); }); app.use("/user",function(err,req,res,next){ console.log("用户登录"); next(err); },function(req,res,next){ res.send("用户登录"); next(); }); app.use(function(req,res){ res.status(404).send("未找到指定页面"); }); app.listen(8080);
从版本4.x开始,Express不再依赖Content,也就是说Express以前的内置中间件作为单独模块,express.static是Express的唯一内置中间件。
express.static(root, [options]);
通过express.static我们可以指定要加载的静态资源。
形如之前我们的body-parser,采用引入外部模块的方式来获得更多的应用操作。如后期的cookie和session。
var express = require('express'); var app = express(); var cookieParser = require('cookie-parser');
以上就是关于express中间件类型,在实际项目中,中间件都是必不可少的,因此熟悉使用各种中间件会加快项目的开发效率。
更多node相关知识,请访问:nodejs 教程!!
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