Express 中的中间件链接

Question

我正在编写 API，想了解添加由多个路由共享的中间件的好方法是什么。中间件在每个路由中做同样的事情，比如验证主机/ip、验证用户等。 req 对象被加载到每个中间件中的其他对象，比如 req.host、req.ip、req.username 等。    app.post("/route1", middleware1, middleware2, middleware3, middleware4);    app.post("/route2", middleware1, middleware2, middleware3, middleware4);    const middleware1 = (req, res, next) => {     // does something to validate user     req.username = "username"     next();    }    const middleware2 = (req, res, next) => {     // host validation     req.host = "something modified in validation"     next();    }    const middleware3 = (req, res, next) => {     // checks for mac and ip     req.mac = "mac addr"     next();    }    const middleware4 = (req, res, next) => {     res.send();    }或者像这样：    app.post("/route1", middleware1);    app.post("/route2", middleware1);    const middleware1 = (req, res) => {      // does something to validate user      req.username = "username"      middleware2(req, res);    }    const middleware2 = (req, res) => {      // host validation      req.host = "something modified in validation"      middleware3(req, res);    }    const middleware3 = (req, res) => {      // checks for mac and ip      req.mac = "mac addr"      middleware4(req, res);    }    const middleware1 = (req, res) => {      res.send();    }谢谢。

Answer 1

通常我不会直接从另一个中间件调用中间件。它混合了中间件逻辑的职责和使用中间件的位置。

Express 的可配置性比您想象的要高得多。您还可以在公共路径中安装公共中间件：

如果所有路由都使用中间件：

// How common middlewares are normally installed:

app.post(middleware1);

app.post(middleware2);

app.post(middleware3);

app.post(middleware4);

// Alternative, less common way to do it:

app.post(middleware1,middleware2,middleware3,middleware4);

如果只有特定的 url模式使用中间件：

// Use a regexp:

app.post(/route(1|2)/, middleware1, middleware2, middleware3, middleware4);

// Or if you don't like regexp, use globs:

app.post('route*', middleware1, middleware2, middleware3, middleware4);

// Or a more specific glob pattern:

app.post('route1?2?', middleware1, middleware2, middleware3, middleware4);

如果子路径中的所有 url 都使用中间件。例如，假设所有 url 都/route/...使用中间件：

const route = express.Router();

app.use('/route',route);

route.post(middleware1);

route.post(middleware2);

route.post(middleware3);

route.post(middleware4);

如果以上都不吸引你，你仍然可以使用你的第二个选项，但不是在彼此内部调用中间件，而是编写一个中间件来初始化中间件：

function commonMiddlewares (req, res, next) {

    middleware1(req,res,function() {

        middleware2(req,res,function() {

            middleware3(req,res,function() {

                middleware4(req,res,next);

            });

        });

    });

}

可以用较少嵌套的方式编写：

function commonMiddlewares (req, res, next) {

    function runMiddleware4 () {

        middleware4(req,res,next);

    }

    function runMiddleware3 () {

        middleware3(req,res,runMiddleware4);

    }

    function runMiddleware2 () {

        middleware2(req,res,runMiddleware3);

    }

    middleware1(req,res,runMiddleware2);

}

Answer 2

const express = require('express')

const { routesMiddleware } =require('./middlewares')

const { pureVaidationsFunctions1 } =require('./services')

const rout1 =express.Router()

const rout2 =express.Router()

const app = express()

app.use('/route1',route1)

app.use('/route2',route2)

// routesMiddleware a middleware to handle the execution of list of functions

// pureVaidationsFunctions1 list of funtions that `routesMiddleware` will consume

route1.post(routesMiddleware(pureVaidationsFunctions1))

route2.post(routesMiddleware(pureVaidationsFunctions2))

有道理？

Answer 3

您可以指定多个中间件，请参阅app.use 文档：

以上任何一项的组合数组。

您可以创建所有中间件的文件，例如 -

中间件.js

module.exports = [

  function(req, res, next){...},

  function(req, res, next){...},

  function(req, res, next){...},

  .

  .

  .

  function(req, res, next){...},

]

然后简单地添加它：

/*

you can pass any of the below inside app.use()

A middleware function.

A series of middleware functions (separated by commas).

An array of middleware functions.

A combination of all of the above.

*/

app.use(require('./middlewares.js'));

注意 - 仅对所有此类请求通用的中间件执行此操作。