I'd like some help as I'm new to Node.js and express. I have the following code which I'm testing on Postman

const Joi = require('@hapi/joi');
const bodyParser = require('body-parser');

// Load the express framework
const express = require('express');
const app = express();

app.use(express.json());
app.use(bodyParser.json());
app.use(express.urlencoded({ extended: true }));

// temp array
const courses = [
    {id: 1, title: 'Learning Node.js'},
    {id: 2, title: 'How to bee a full stack dev'},
    {id: 3, title: 'Master your Javascript skills'}
];
app.post('/api/courses', (request, response) => {
    let error = validateCourse(request.body);
    if (error) {
        response.status(400).send(error.details[0].message); // *
        return;
    }

    let course = {
        id: courses.length + 1,
        name: request.body.name
    };

    // TODO save
    console.log('TODO save the record');

    response.send(course);
});

app.put('/api/courses/:id', (request, response) => {
    let course = courses.find(c => c.id === parseInt(request.params.id));
    if(!course) response.status(404).send('Oops!');

    let { error } = validateCourse(request.body);
    if (error) {
        response.status(400).send(error.details[0].message);
        return;
    }

    // TODO save
    console.log('TODO save the record');

    response.send(course);
});


function validateCourse(course) {
    let schema = Joi.object({
        name: Joi.string().min(4).required()
    });
    console.log(course);
    return schema.validate(course);
}

Either when I make a PUT or a POST request in which I supply a name (i.e the validation should pass) I get a 400 error.

On POST request I see the following in the console which refers to where my asterisk (*) is

TypeError: Cannot read property '0' of undefined
    at /app/index.js:50:48

On PUT request I see the following in the console Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client

In both cases the console.log I have in the validateCourse function is showing an empty object {}

This is a screenshot from postman

Any ideas what I'm doing wrong?

I'd like some help as I'm new to Node.js and express. I have the following code which I'm testing on Postman

const Joi = require('@hapi/joi');
const bodyParser = require('body-parser');

// Load the express framework
const express = require('express');
const app = express();

app.use(express.json());
app.use(bodyParser.json());
app.use(express.urlencoded({ extended: true }));

// temp array
const courses = [
    {id: 1, title: 'Learning Node.js'},
    {id: 2, title: 'How to bee a full stack dev'},
    {id: 3, title: 'Master your Javascript skills'}
];
app.post('/api/courses', (request, response) => {
    let error = validateCourse(request.body);
    if (error) {
        response.status(400).send(error.details[0].message); // *
        return;
    }

    let course = {
        id: courses.length + 1,
        name: request.body.name
    };

    // TODO save
    console.log('TODO save the record');

    response.send(course);
});

app.put('/api/courses/:id', (request, response) => {
    let course = courses.find(c => c.id === parseInt(request.params.id));
    if(!course) response.status(404).send('Oops!');

    let { error } = validateCourse(request.body);
    if (error) {
        response.status(400).send(error.details[0].message);
        return;
    }

    // TODO save
    console.log('TODO save the record');

    response.send(course);
});


function validateCourse(course) {
    let schema = Joi.object({
        name: Joi.string().min(4).required()
    });
    console.log(course);
    return schema.validate(course);
}

Either when I make a PUT or a POST request in which I supply a name (i.e the validation should pass) I get a 400 error.

On POST request I see the following in the console which refers to where my asterisk (*) is

TypeError: Cannot read property '0' of undefined
    at /app/index.js:50:48

On PUT request I see the following in the console Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client

In both cases the console.log I have in the validateCourse function is showing an empty object {}

This is a screenshot from postman

Any ideas what I'm doing wrong?

• javascript
• node.js
• express
• request
• postman

• In your error handling you should return to stop the function otherwise you'll try to send the response 2 times, hence the "Cannot set headers after they are sent" – Mickael B. Commented Jan 23, 2020 at 15:23
• I've added the return in the if (error) block but still the validation fails even if I submit a value in the name – ltdev Commented Jan 23, 2020 at 15:27
• like in the put, in the post you need to destruct error like this: let { error } = validateCourse(request.body); – SuleymanSah Commented Jan 23, 2020 at 16:24
• As I'm trying to debug it I've notice that the request.body is always set as undefined so I never actually send a request with the name any ideas why this may happen? I'm using app.use(express.json()); at the top of the file after loading express and also I can see I'm having the body-parser in the node_modules – ltdev Commented Jan 23, 2020 at 16:42
• Can you add your main file (index, app or server.js) to the question? – SuleymanSah Commented Jan 23, 2020 at 17:12

2 Answers 2