Sending data to and getting data from node.js?

Question

In my React code I send a 'post' and 'get' request. My problems are in my server side code, I think.

General

const express = require('express');

const app = express();

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

app.use(bodyParser.urlencoded({ extended: false }));
app.use(cors());

const posts = [
    {
        "postId": 1,
        "id": 1,
        "title": "To be or not to be",
        "body": "Yes, that is the question"
    },
    {
        "postId": 1,
        "id": 2,
        "title": "So What?",
        "body": "What do you want"
    }
];

Note: Context, code above comes before the problem code

Resolved 1) Post

User clicks 'Submit' a post request sends data to server

Problem:

1) The 'req.body' is empty

fetch("http://localhost:3001/create", {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json'
      },
      body: JSON.stringify(post)
    })
      .then(res => this.props.history.push('/posts'))
      .catch(err => this.setState({error: true}))

    this.setState({
      title: "",
      body: ""
    })

app.post('/create', (req, res, next)=>{
    // Request body is empty, why?
    console.log(req.body);
})

Solution:

POST request is sending data in JSON format because of JSON.stringify(post) , we need to parse this JSON data so we can use app.use(bodyParser.json()); , and there we have it. SOLVED

Resolved 2) Get

In the first get request I am sending the 'id' of the object as URL params and trying to receive the corresponding object from the server, req is sent correctly.

Problem: Receive the following error in the 'findPostById' function:

TypeError: Cannot read property id of undefined

fetch(`http://localhost:3001/posts/${this.props.match.params.id}`)
            .then(res=>res.json())
            .then(data=>this.setState({loadedPost: data}))
            .catch(err=>console.log(err))

app.get('/posts/:id', (req, res, next)=>{
    // Correct, receive id
    let id = req.params.id;

    findPostById(id, (post, err)=>{
        if(err){
            console.log(err);
        }
        else{
            res.send(post)
        }
    })
})

let findPostById = (id, cb)=>{
    console.log(id, 'Correctly receive the id');
    let post = posts.find((post)=>{
        return post.id === id;
    })
    // Receive: 'TypeError: Cannot read property id of undefined'
    console.log(post.id);
    if(post){
        cb(post, null);
    }
    else{
        cb(null, new Error('Could not find post', id));
    }
}

Solution:

post.id is type 'number' and id is of type 'string', return post.id === id; result in false because of strict equality. So, we convert id to number with +id `return post.id === +id;

Answer 1

Check if in your server side code is missing below configuration.

const bodyParser = require("body-parser");

app.use(bodyParser.json({ limit: "50mb" }));
app.use(bodyParser.urlencoded({ extended: false }));

body parser allows you to access req.body from within your routes

Answer 2

For problem 1,

Please try to add this.

app.use(bodyParser.json());