express.js中的路由错误

Question

I'm trying to learn expressjs, and have been trying to figure out a way to add MVC structure into it. For some reason, I get a 404 error when i try to access localhost:3000.

My directory structure is:

• App
  • app.js
  • routes.js
  • controllers
  • views
  • etc.

App.js:

mymodule = {

/* initialize 
 * ==============================
 * load dependencies & external node modules, setup engines */ 
initialize: function() {

    // load modules
    this.express = require('express');
    this.path = require('path');
    this.favicon = require('static-favicon');
    this.logger = require('morgan');
    this.cookieParser = require('cookie-parser');
    this.bodyParser = require('body-parser');

    // initialize main express app.
    this.app = this.express();

    // attach view engine to app
    this.app.set('views', this.path.join(__dirname, 'views')); // view files are in /views/
    this.app.set('view engine', 'jade');

    // attach modules to app
    this.app.use(this.favicon());
    this.app.use(this.logger('dev'));
    this.app.use(this.bodyParser.json());
    this.app.use(this.bodyParser.urlencoded());
    this.app.use(this.cookieParser());
    this.app.use(this.express.static(this.path.join(__dirname, 'public'))); // static files are in /public/
},

/* setErrorHandlers
 * ===============================
 * set error handlers for routing */
setErrorHandlers: function() {
    if (this.app == undefined) {    
        console.log("caught an attempt to set error handlers without initializing");
    } else {

        // Catch 404 Error and forward to error handler 
        this.app.use(function(req, res, next) {
            console.log("Caught 404 Error");
            var err = new Error('Not Found');
            err.status = 404;
            next(err);
        });

        // Error Handlers

        // 1) Dev Error Handler. print stack trace
        if (this.app.get('env') === 'development') {
            this.app.use(function(err, req, res, next) {
                res.status(err.status || 500);
                res.render('error', {
                    message: err.message,
                    error: err
                });
            });
        }

        // 2) Production Error Handler

        this.app.use(function(err, req,res, next) {
            res.status(err.status || 500);
            res.render('error', {
                message: err.message,
                error: {}
            });
        });
    }
},

/* setRouters
 * ================================
 * */
setRouters: function() {
    // get all routes 
    this.routes = require('./routes').construct(this.app);

}
}

mymodule.initialize();
mymodule.setErrorHandlers();
mymodule.setRouters();

module.exports = mymodule.app;'

routes.js:

var index_controller = require('./controllers/index').controller();

module.exports.construct = function(app) {
    console.log("got here");
    //app.get('/', require('./controllers/index').about);
    //app.get('/', index_controller.index);
    app.get('/', function(req,res) {res.send("sdf");});
}

./controllers/index.js:

module.exports.controller = function() {
index_action = function(req, res) {
    if (req == undefined) {
        console.log("req undefined!");
    } else {
    console.log(req);
    res.render('index', {title: 'Express'});
    }
}

return {index: index_action};

}

I put the code on github repo: https://github.com/sjang92/expressjs-mvc/blob/master/controllers/index.js

Does anyone know why it's happening?

Thank you

Answer 1

You're adding a normal middleware function that responds to the request before your app.get('/', ..); handler has a chance to execute:

    this.app.use(function(req, res, next) {
        console.log("Caught 404 Error");
        var err = new Error('Not Found');
        err.status = 404;
        next(err);
    });

You should instead only add this kind of middleware after all of your other routes. For example:

mymodule.initialize();
mymodule.setRouters();
mymodule.setErrorHandlers();