The core usage of egg.js middleware

First, use middleware in your application

1. Create a new auth2.js in the app/ Middleware folder

module.exports = (option,app) = > {

  return async function auth2(ctx,next) {

    console.log(new Date);

    // The following statement is very important. Without this statement, the thread would terminate at this point
    awaitnext(); }}Copy the code

2. Registered middleware

Register in config.default.js.

config.middleware = ['auth2'];
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3. Pass parameters to the middleware

config.middleware = ['auth2'];
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4. The middleware reads the passed parameters

return async function auth2(ctx,next) {
    console.log(option);

    console.log(new Date);

    // The following statement is very important. Without this statement, the thread would terminate at this point
    await next();
  }
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Using middleware in router.js

The goal of this section is to configure middleware for the specified route. This method does not need to register routes in config.default.js.

1. Middleware is defined in the same way as above.
2. Get the middleware in router.js and specify which routes can be triggered.

module.exports = app= > {
  const { router, controller } = app;
  const auth = app.middleware.auth();
  router.get('/',auth, controller.home.setSession);
  router.get('/news', controller.news.index);
  router.get('/deletecookie',controller.home.deletecookie)
};
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Middleware that uses KOA in egg.js

The following is a systematic illustration of the use of koA-JSONP middleware in Egg.

1. Installation of koa – the json

npm install koa-jsonp
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2. Create a new jsonp.js in app/ Middleware

// Configure the middleware for KOA

const jsonp = require('koa-jsonp');

module.exports = jsonp;
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3. Register middleware (in config.default.js)

config.middleware = ['jsonp'];
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4. Request to specify path

http:/ / 127.0.0.1:7001 / shop? callback=666
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We continue with a piece of KOA-COMPRESS middleware that enables server Gzip compression.

1. Installation of koa – compress

npm install koa-compress
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2. Create a new compress. Js under app/ Middleware

module.exports = require('koa-compress');
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3. Registered middleware

config.middleware = ['jsonp'.'compress'];
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4. Configure middleware parameters

config.compress = {
    threshold: 1024   // Set the compression threshold
}
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The files that access the specified page are compressed.

If non-standard middleware is used, the definition of middleware is as follows:

// The following illustrates the use of non-standard middleware

const middleWare = require('xxx');

module.exports = (option,app) = > {
  return middleWare(options1,options2)
}
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General configuration of middleware

The following three common configuration items are supported by both reference layer loaded middleware and framework reloaded middleware.

1. Enable: controls whether the middleware is enabled.
2. Match: Sets that only requests that match certain rules will pass through this middleware.
3. Ignore: Sets requests that comply with certain rules not to pass through this middleware.

• Disabling a middleware

config.compress = {
    enable: false.threshold: 10   // Set the compression threshold
  }
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• Sets a route to match the middleware

config.auth = {
    match: '/news'.title: 'auth hello'
  }
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If you want to ignore a route, use the following notation

config.auth = {
    ignore: '/news'.title: 'auth hello'
  }
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If we are dealing with a more complex routing situation, we can also use the following match method

config.auth = {
    match(ctx) {
      if (ctx.request.url === '/shop' || ctx.request.url === "/news") {
        return true;
      }
      return false
    },
    title: 'auth hello'
  }
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Five, set the unauthorized user cannot access the specified page

1. Create the specified middleware under app/ Middleware /

module.exports = (option,app) = > {
  return async function auth(ctx,next) {
    if (ctx.session && ctx.session.userinfo) {
      await next()
    } else {
      if (ctx.request.url === '/') {
        await next();
      } else {
        ctx.redirect('/'); }}}}Copy the code

2. Registered middleware

  config.middleware = ['auth'.'compress'.'adminAuth'];
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3. Causes the specified route to trigger the middleware

  config.adminAuth = {
    match: '/admin/user'
  }
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