Javascript 如何在Express中获取URL参数？

我在从我的URL获取

tagid

的值时遇到了一个问题：

localhost:8888/p？tagid=1234

请帮助我更正控制器代码。我无法获取

tagid

值

我的代码如下：

app.js

：

var express = require('express'),
  http = require('http'),
  path = require('path');
var app = express();
var controller = require('./controller')({
  app: app
});

// all environments
app.configure(function() {
  app.set('port', process.env.PORT || 8888);
  app.use(express.json());
  app.use(express.urlencoded());
  app.use(express.methodOverride());
  app.use(app.router);
  app.use(express.static(path.join(__dirname, 'public')));
  app.set('view engine', 'jade');
  app.set('views', __dirname + '/views');
  app.use(app.router);
  app.get('/', function(req, res) {
    res.render('index');
  });
});
http.createServer(app).listen(app.get('port'), function() {
  console.log('Express server listening on port ' + app.get('port'));
});

function controller(params) {
  var app = params.app;
  //var query_string = request.query.query_string;

  app.get('/p?tagId=/', function(request, response) {
    // userId is a parameter in the url request
    response.writeHead(200); // return 200 HTTP OK status
    response.end('You are looking for tagId' + request.route.query.tagId);
  });
}

module.exports = controller;

require('./controllers');
/*
 * GET home page.
 */

exports.index = function(req, res) {
  res.render('index', {
    title: 'Express'
  });
};

Controller/index.js

：

var express = require('express'),
  http = require('http'),
  path = require('path');
var app = express();
var controller = require('./controller')({
  app: app
});

// all environments
app.configure(function() {
  app.set('port', process.env.PORT || 8888);
  app.use(express.json());
  app.use(express.urlencoded());
  app.use(express.methodOverride());
  app.use(app.router);
  app.use(express.static(path.join(__dirname, 'public')));
  app.set('view engine', 'jade');
  app.set('views', __dirname + '/views');
  app.use(app.router);
  app.get('/', function(req, res) {
    res.render('index');
  });
});
http.createServer(app).listen(app.get('port'), function() {
  console.log('Express server listening on port ' + app.get('port'));
});

function controller(params) {
  var app = params.app;
  //var query_string = request.query.query_string;

  app.get('/p?tagId=/', function(request, response) {
    // userId is a parameter in the url request
    response.writeHead(200); // return 200 HTTP OK status
    response.end('You are looking for tagId' + request.route.query.tagId);
  });
}

module.exports = controller;

require('./controllers');
/*
 * GET home page.
 */

exports.index = function(req, res) {
  res.render('index', {
    title: 'Express'
  });
};

routes/index.js

：

var express = require('express'),
  http = require('http'),
  path = require('path');
var app = express();
var controller = require('./controller')({
  app: app
});

// all environments
app.configure(function() {
  app.set('port', process.env.PORT || 8888);
  app.use(express.json());
  app.use(express.urlencoded());
  app.use(express.methodOverride());
  app.use(app.router);
  app.use(express.static(path.join(__dirname, 'public')));
  app.set('view engine', 'jade');
  app.set('views', __dirname + '/views');
  app.use(app.router);
  app.get('/', function(req, res) {
    res.render('index');
  });
});
http.createServer(app).listen(app.get('port'), function() {
  console.log('Express server listening on port ' + app.get('port'));
});

function controller(params) {
  var app = params.app;
  //var query_string = request.query.query_string;

  app.get('/p?tagId=/', function(request, response) {
    // userId is a parameter in the url request
    response.writeHead(200); // return 200 HTTP OK status
    response.end('You are looking for tagId' + request.route.query.tagId);
  });
}

module.exports = controller;

require('./controllers');
/*
 * GET home page.
 */

exports.index = function(req, res) {
  res.render('index', {
    title: 'Express'
  });
};

---

Express 4.x

要获取URL参数的值，请使用

如果要获取查询参数

？tagId=5

，请使用

---

Express 3.x

URL参数

app.get('/p/:tagId', function(req, res) {
  res.send("tagId is set to " + req.param("tagId"));
});

// GET /p/5
// tagId is set to 5

app.get('/p', function(req, res) {
  res.send("tagId is set to " + req.query("tagId"));
});

// GET /p?tagId=5
// tagId is set to 5

查询参数

app.get('/p/:tagId', function(req, res) {
  res.send("tagId is set to " + req.param("tagId"));
});

// GET /p/5
// tagId is set to 5

app.get('/p', function(req, res) {
  res.send("tagId is set to " + req.query("tagId"));
});

// GET /p?tagId=5
// tagId is set to 5

---

您可以执行类似于

req.param（'tagId'）

的操作，如果您想获取URL中的查询参数值，请按照下面的代码片段进行操作

//url.localhost:8888/p?tagid=1234
req.query.tagid
OR
req.param.tagid

---

如果要使用Express param函数获取URL参数

Express param函数获取特定参数。这被认为是中间件，将在调用路由之前运行

这可用于验证或获取有关项目的重要信息

例如：

// parameter middleware that will run before the next routes
app.param('tagid', function(req, res, next, tagid) {

// check if the tagid exists
// do some validations
// add something to the tagid
var modified = tagid+ '123';

// save name to the request
req.tagid= modified;

next();
});

// http://localhost:8080/api/tags/98
app.get('/api/tags/:tagid', function(req, res) {
// the tagid was found and is available in req.tagid
res.send('New tag id ' + req.tagid+ '!');
});

---

如果您的路由如下所示，这将起作用：

localhost:8888/p？tagid=1234

var tagId = req.query.tagid;
console.log(tagId); // outputs: 1234
console.log(req.query.tagid); // outputs: 1234

var tagId = req.params.tagid;
console.log(tagId); // outputs: 1234
console.log(req.params.tagid); // outputs: 1234

否则，如果您的路线如下所示，请使用以下代码：

localhost:8888/p/1234

var tagId = req.query.tagid;
console.log(tagId); // outputs: 1234
console.log(req.query.tagid); // outputs: 1234

var tagId = req.params.tagid;
console.log(tagId); // outputs: 1234
console.log(req.params.tagid); // outputs: 1234

---

您使用的是哪个版本的express？我刚刚在

express-3.4.4

上对此进行了测试，效果很好。如果使用顶部解决方案，请记住使用

/p/5

，如果使用底部解决方案，请记住使用

/p？tagId=5

。顶部解决方案（/p/5）非常适合我。但是底部一个/p？tagId=5会给我错误“tagId设置为未定义”非常感谢macek。你节省了我的时间。这是我的错误，我完全按照你说的做了，但在url中我使用了“tagid”而不是“tagid”。

req.param（）

是：

使用req.params、req.body或req.query，如果适用。

对于命名路由“参数”（例如

/p/：tagid

）使用。对于查询字符串（例如，

/p？tagId=5

）使用。在express中，

/p？tagId=1234

，tagId称为查询字符串，而不是URL参数。URL参数应为

/p/：tagId

。此方法已被弃用。改为使用req.query。@alextc

req.query

和

req.params

是如此不同的事情，替换

req.param（'x'）

的是

req.params.x

而不是req.query。通常人们不会这样创建url

/p/：tagid=1234