为什么邮递员给我“未找到 404”错误？答案

【问题标题】：Why Postman gives me "Not Found 404" error?为什么邮递员给我“未找到 404”错误？
【发布时间】：2020-04-10 06:58:01
【问题描述】：

当我向 https://localhost:3443/images/ 端点发送 GET 请求时，我得到以下结果：

[

    {
        "_id": "5e8ef5fa98c70f30a8986070",
        "createdAt": "2020-04-09T10:16:26.796Z",
        "updatedAt": "2020-04-09T10:16:26.796Z",
        "__v": 0
    },
    {
        "_id": "5e8efb70070f0b39103cba71",
        "createdAt": "2020-04-09T10:39:44.196Z",
        "updatedAt": "2020-04-09T10:39:44.196Z",
        "__v": 0
    },
    {
        "_id": "5e90150dd9812057f81784f3",
        "createdAt": "2020-04-10T06:41:17.633Z",
        "updatedAt": "2020-04-10T06:41:17.633Z",
        "__v": 0
    }
]

但是当我尝试将这些 ID 中的每一个添加到我的 URL 末尾时，例如 https://localhost:3443/images/5e90150dd9812057f81784f3，它给了我 Not Found 404 错误消息。

我的 app.js：

var express = require('express');
var path = require('path');
var favicon = require('serve-favicon');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');

var index = require('./routes/index');
var usersRouter = require('./routes/usersRouter');
var imagesRouter = require('./routes/imagesRouter');
const uploadRouter = require('./routes/uploadRouter');

const Images = require('./models/images');




//const uploadRouter = require('./routes/uploadRouter');
//const favoriteRouter = require('./routes/favoriteRouter')
var config = require('./config');

const mongoose = require('mongoose');
//mongoose.set('useCreateIndex', true);
mongoose.Promise = require('bluebird');

var passport = require('passport');
var authenticate = require('./authenticate');

// Connection URL
const url = config.mongoUrl;
const connect = mongoose.connect(url, {
    //useMongoClient: true,
    /* other options */
     useNewUrlParser: true ,
     useUnifiedTopology: true 
  });

connect.then((db) => {
    console.log("Connected correctly to server");
}, (err) => { console.log(err); });

var app = express();

// Secure traffic only
app.all('*', (req, res, next) => {
  if (req.secure) {
    return next();
  }
  else {
    res.redirect(307, 'https://' + req.hostname + ':' + app.get('secPort') + req.url);
  }
});

// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');

// uncomment after placing your favicon in /public
//app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));



app.use(passport.initialize());

app.use('/', index);
app.use('/users', usersRouter);


app.use(express.static(path.join(__dirname, 'public')));

app.use('/images',imagesRouter);
app.use('/imageUpload',uploadRouter);

//app.use('/imageUpload',uploadRouter);
//app.use('/favorites',favoriteRouter);

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

// error handler
app.use(function(err, req, res, next) {
  // set locals, only providing error in development
  res.locals.message = err.message;
  res.locals.error = req.app.get('env') === 'development' ? err : {};

  // render the error page
  res.status(err.status || 500);
  res.render('error');
});

module.exports = app;

我的 imageRouter.js：

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

const Images = require('../models/images');
var authenticate = require('../authenticate');

const imagesRouter = express.Router();
const cors = require('./cors');

imagesRouter.use(bodyParser.json());

imagesRouter.options('*', cors.corsWithOptions, (req, res) => { res.sendStatus(200); } );


imagesRouter.route('/')
//.options(cors.corsWithOptions, (req, res) => { res.sendStatus(200); })
.get(cors.cors, (req,res,next) => {
    Images.find({})
    .then((images) => {
        res.statusCode = 200;
        res.setHeader('Content-Type', 'application/json');
        res.json(images);

    }, (err) => next(err))
    .catch((err) => next(err));
})



module.exports = imagesRouter;

【问题讨论】：

标签： node.js get postman express-router

【解决方案1】：

您必须为查询参数定义一个端点。

app.get("/images/:id",async (req,res)=>{
    const id=req.params.id
    const image=await Images.findById(id)
    if(!image) res.send(`no image exists with given ${id}`)
    res.send(image))
})

由于您使用的是猫鼬，因此您必须有一个模型。我刚刚命名了图像，它应该在您查询的同一页面上导入。

在猫鼬中，所有的查询操作都是异步操作。

【讨论】：