javascript - Node JS |类型错误 : Cannot read property 'first_name' of undefined

Question

我刚开始使用 MEAN 应用程序，但在向数据库中添加数据时遇到了困难。所以请帮我找到解决方案。

这是根文件，应用程序的入口点

//Importing  modules
var express=require('express');
var mongoose=require('mongoose');
var bodyparser=require('body-parser');
var cors=require('cors');
var path=require('path');

var app=express();
const route=require('./routes/route');

//Connect to mongoDb
mongoose.connect('mongodb://localhost:27017/contactlist');

//on connection
mongoose.connection.on('connected',()=>{
    console.log("Successfully established a connection to mongodb Database ")
});

//on error
mongoose.connection.on('error',(err)=>{
    if(err){
        console.log("Failed to established a connection "+err);
    }
});
const port=3000;
//For routing
app.use('/api',route);

//Adding middleware -cors
app.use(cors());

//body-parser
app.use(bodyparser.json());

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

//port no


app.get('/',(req,res)=>{
    res.send('Foobar');
});

app.listen(port,()=>{
    console.log("Server started listening to port "+port);  
})

这是我的路线文件，

const express = require('express');
const router = express.Router();
// fetching the schema
const Contact = require('../Models/contacts');
//Retriving the contacts
router.get('/contacts', (req,res,next)=>{
    Contact.find(function(err,contacts){
        // Sending to client in json format
        res.json(contacts); 
    });
});

// Adding Contacts
router.post('/contact', (req,res,next)=>{
    let newContact = new Contact({
        first_name : req.body.first_name,
        last_name : req.body.last_name,
        phone : req.body.phone
    });

    newContact.save((err,contact)=>{
        if(err){
            res.json({msg: "Failed to add contact."});
        }else{
            res.json({msg:"Contact added sucessfully"});
        }
    });
});

//Deleteing contact
router.delete('/contact/id',(req,res,next)=>{
    Contact.remove({_id:req.params.id},function(err,result){
        if(err){
            res.json(err);
        }else{
            res.json(result);
        }
    })  
});

module.exports=router;

现在，我正在尝试使用 postman 在 DB (Mongo DB) 中添加一些记录，但它抛出了一条错误消息“TypeError: Cannot read property 'first_name' of undefined, at router.post (C:\Mean App\ContactList\routes\route.js:16:25)"

在 postman 中，对于 header ，我使用“Content-type: application/json”，在原始正文中，我像这样添加 JSON 数据，

{
    "first_name" : "Siddhesh",
    "last_name" : "Mishra",
    "phone" : "9594106324"
}

这是我创建模式的代码

const mongoose=require('mongoose');
const ContactSchema = mongoose.Schema({
    first_name:{
        type:String,
        required:true
    },
    last_name:{
        type:String,
        required:true
    },
    phone:{
        type:String,
        required:true
    }
});

const Contact=module.exports=mongoose.model('Contact',ContactSchema);

谢谢。

Answer 1

你必须将 body-parser 移动到路由 use 之上，应该可以工作

//body-parser
app.use(bodyparser.json());

//For routing
app.use('/api',route);

来自 Express API v4.x

app.use([path,] callback [, callback...])

...

Middleware functions are executed sequentially, therefore the order of middleware inclusion is important.