Question

我是Node和Express的新手，所以到目前为止我的知识是有限的。我有Node.js，Express和MongoDB的设置。我正在尝试路由请求＆＃34; localhost：3000 / v1 / user＆＃34;通过在我的主.js文件中这样做：

MongoClient.connect(mongoUrl, function (err, db) {
        if (err) {
          console.log("Unable to connect to the mongoDB server. Error:", err);
        } else {
          //HURRAY!! We are connected. :)
          console.log("Connection established to Mongo DB with connection string " + connection_string);


          let port = process.env.NODE_PORT || 3000;
          app.listen(port);
          console.log('Server is now listening to port ' + port);

          app.use(function(req, res){
            req.db = db;
            console.log("DB now available for all routes");
          });


          console.log("Using v1");
          app.use('/v1', v1Route);
        }
      });

与mongo的连接建立正常。我在两个单独的文件中有两个路由器，如下所示：

v1Route：

var express = require('express')
var router = express.Router();

const userRoute = require('./userRoute');

router.use('/user', userRoute);

module.exports = router;

userRoute：

const express = require('express');
var router = express.Router();

router.get('/', function(req,res){
  console.log('fetching all users');
  var collection = req.db.collection('user');
  collection.find().toArray(function (err, result) {

     if (err) {
       console.log(err);
     } else if (result.length > 0) {
       console.log('Found entry');
       res.status(200).send('Found:' + result[0].firstName + ' ' + result[0].lastName).end();
     } else {
       console.log('No document(s) found with defined "find" criteria!');
       res.status(200).send('No document(s) found with defined "find" criteria!').end();
     }
   })


});

module.exports = router;

问题是当我尝试发出请求＆＃34; localhost：3000 / v1 / user＆＃34;时没有任何反应。我没有错误，只是一个停止的浏览器。当我发送请求时，我得到了日志字符串＆＃34; DB现在可用于所有路由＆＃34;。

Answer 1

在您的中间件功能中，您没有调用next处理程序，因此未执行下一个中间件：

app.use(function(req, res, next) {
   req.db = db;
   console.log("DB now available for all routes");
   next();
});

您可以在官方express网站上查看有关编写中间件的更多文档：http://expressjs.com/en/guide/writing-middleware.html

Answer 2

您必须在app.use之后启动服务器（＆＃39; / v1＆＃39;，v1Route）;

MongoClient.connect(mongoUrl, function (err, db) {
        if (err) {
          console.log("Unable to connect to the mongoDB server. Error:", err);
        } else {
          //HURRAY!! We are connected. :)
          console.log("Connection established to Mongo DB with connection string " + connection_string);

          app.use(function(req, res){
            req.db = db;
            console.log("DB now available for all routes");
          });


          console.log("Using v1");
          app.use('/v1', v1Route);

          let port = process.env.NODE_PORT || 3000;
          app.listen(port);
          console.log('Server is now listening to port ' + port);
        }
      });

Node.js REST与Express没有响应

2 个答案: