我们如何将参数传递给 nodeJS 中的已安装路由？

Question

我正在上 NodeJS 课程，有一些与路由相关的作业，一切正常，除了这部分看起来有点奇怪：出于某种原因，我无法读取传递给挂载的参数 ID路由器。

dish.js

const express = require('express');
const bodyParser = require('body-parser');
const dishRouter = express.Router();

dishRouter.use(bodyParser.json());

dishRouter.route('/')
.all((req,res,next) => {
    res.statusCode = 200;
    res.setHeader('Content-Type','text/plain');
    next();
})
.get((req,res) => {
    console.info('Info: ',req);
    res.end(`Sending details of the dish back to you: ${req.params.dishId}`);
})
.post((req,res) => {
    res.statusCode = 403;
    res.end(`Operation not supported: ${req.params.dishId}`);
})
.put((req,res) => {
    res.write(`Updating the dish...: ${req.params.dishId} \n` );
    res.end(`Will update this dish: ${req.body.name} with details: ${req.body.description}`);
})
.delete((req,res) => {
    res.end(`Deleting this dish: ${req.params.dishId}`);
});

exports.dish = dishRouter;

dishes.js

const express = require('express');
const bodyParser = require('body-parser');
const dishesRouter = express.Router();

dishesRouter.use(bodyParser.json());

dishesRouter.route('/')
.all((req,res,next) => {
    res.statusCode = 200;
    res.setHeader('Content-Type','text/plain');
    next();
})

.get((req,res) => {
    res.end('Sending all dishes back to you');
})  

.post((req,res) => {
    res.end(`Will add the dish: ${req.body.name} with details: ${req.body.description}`);
})

.put((req,res) => {
    res.statusCode = 403;
    res.end(`Operation not supported.`);
})

.delete((req,res) => {
    res.end(`Deleting all dishes.....`);
});

exports.dishes = dishesRouter;

index.js

const express = require('express');
const morgan = require('morgan');
const bodyParser = require('body-parser');
const http = require('http');
const dishRouter = require('./routes/dish');
const dishesRouter = require('./routes/dishes');
const hostname = 'localhost';
const port = 3000;

const app = express();
app.use(morgan('dev'));
app.use(bodyParser.json());

app.use('/dishes',dishesRouter.dishes);
app.use('/dishes/:dishId',dishRouter.dish);

app.use(express.static(__dirname+'/public'));

app.use((req,res,next) => {
    res.statusCode = 200;
    res.setHeader('Content-Type','text/html');
    res.end('<html><body><h1>This is an Express Server</h1></body></html>');
});

const server = http.createServer(app);

server.listen(port,hostname,(req,res) => {
   console.info(`Server running on port: ${port}, at: ${hostname}`);
})

此 GET localhost:3000/dishes/123 正在调用正确的路由，但参数 dishId 返回为“未定义”。同样，刚刚学习 nodeJS，我的 receiver/mounted 路由似乎应该可以很好地接收这些参数，可以正确读取主体，但不能正确读取参数。 ...谢谢。

Answer 1

是的，参数不会在路由器之间流动。您使用的是新路由器，因此需要新的路由参数对象。

您可以查看代码： https://github.com/expressjs/express/blob/master/lib/router/index.js#L43 查看第 43 行和第 53 行，其中 route.params 设置为空对象。

一些例子：

index.js

app.use('/dishes/:dishId',(req, res) => {
  console.log('now I get my dishId', req.params.dishId)
});

dish.js（版本 1）

dishRouter.route('/')
.get((req, res) => {
  console.log('now i get nothing', req.params)
})

dish.js（版本 2）

dishRouter.route('/:anotherId')
.get((req, res) => {
  console.log('now we get another parameter', req.params.anotherId)
})
// the path would be /dish/123/456

我不确定是否有 offical-expressjs-way 在路由器之间传递参数对象。

一个解决方案是创建自定义处理程序

index.js

app.use('/dishes/:dishId', handler)

handler.js

function handler (req, res, next) {
  if (req.method === 'GET') {
    console.log('now we get it', req.params)
  }
}

module.exports = handler

另一种方法是在调用路由器之前将 dishId 添加到请求对象中：

index.js

app.use('/dishes/:dishId', (req, res, next) => {
  req.dishId = req.params.dishId
  router(req, res, next)
})

dish.js

const express = require('express')
const router = express.Router()
  router.route('/')
  .get((req, res) => {    
    console.log('nothing here', req.params)
    console.log('dishId', req.dishId)
  })

module.exports = router

第三种方式是将参数作为选项发送给路由函数

index.js

app.use('/dishes/:dishId', (req, res, next) => {
  router(req.params)(req, res, next)
})

dish.js

function createRouter (options) {
  const router = express.Router()
  router.route('/')
  .get((req, res) => {    
    console.log('nothing here', req.params)
    console.log('but alot here', options)
  })

  return router
}

module.exports = createRouter

如果您愿意，您也可以将 :dishId 作为可选参数放在路由器上

index.js

app.use('/dishes', dishesRouter)

dishes.js

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

router.route('/:dishId?')
  .get((req, res) => {        
    if (req.params.dishId) {
      res.end(`Sending details of the dish back to you: ${req.params.dishId}`)
    } else {
      res.end('Sending all dishes back to you');
    }
  })

module.exports = router

我们如何将参数传递给 nodeJS 中的已安装路由？

How do we pass parameters to a mounted route in nodeJS?

node.js

express

path-parameter

express-router