Cross-Origin Request Blocked even after adding headers in server code - node.js

Question

I've a simple API in Express/Node and I also have a simple angular application for posting blogs. The only problem is when I hit the /contribute route using POST method. I'm getting this error on both chrome and firefox:
error: error { target: XMLHttpRequest, isTrusted: true, lengthComputable: false, … }
​
headers: Object { normalizedNames: Map(0), lazyUpdate: null, headers: Map(0) }
​
message: "Http failure response for localhost:3000/api/contribute: 0 Unknown Error"
​
name: "HttpErrorResponse"
​
ok: false
​
status: 0
​
statusText: "Unknown Error"
​
url: "localhost:3000/api/contribute"
​
: {…}
​​
constructor: class HttpErrorResponse { constructor(init) }​​
: {…}
​​​
constructor: class HttpResponseBase { constructor(init, defaultStatus, defaultStatusText) }​​​
: {…
Here's my server side code.
api.js
...
router.post('/contribute', (req, res) => {
console.log('Pushing new article');
let userPost = req.body;
let post = new Post(userPost);
post.save((error, registeredPost) => {
if (error) {
console.log(error);
} else {
res.status(200).send(registeredPost);
}
})
})
...
module.exports = router;
server.js
const express = require('express');
const bodyParser = require('body-parser');
const app = express();
const api = require('./routes/api');
const cors = require('cors');
app.use(bodyParser.json());
// app.use(cors({ origin: 'http://localhost:4200' })); <--- TRIED THIS ALSO
app.use(function (req, res, next) {
// Website you wish to allow to connect
res.setHeader('Access-Control-Allow-Origin', 'http://localhost:4200');
// Request methods you wish to allow
res.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS, PUT, PATCH, DELETE');
// Request headers you wish to allow
res.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type');
// Set to true if you need the website to include cookies in the requests sent
// to the API (e.g. in case you use sessions)
res.setHeader('Access-Control-Allow-Credentials', true);
// Pass to next layer of middleware
next();
});
app.use('/api', api);
app.get('/', function(req, res) {
res.send('Server is up and running!');
})
app.listen(3000, function() {
console.log('Server listening port:3000');
});
Yes, server is up and running.
Here is angular code.
auth.service.ts
private _contributeUrl = "https://localhost:3000/api/contribute";
...
pushNewPost(newPost) {
console.log("here is the new post", newPost); // GETTING CORRECT OUTPUT
return this._http.post<any>(this._contributeUrl, newPost);
}
contribute.component.ts
this._auth.pushNewPost(this.makeNewPost)
.subscribe (
res => {
(<HTMLInputElement>document.getElementById("inputTitle")).value="";
this.editorForm.reset();
this.addSingle();
},
err => console.log(err)
);
Now the fun part is that the same code is working perfectly when I make a post request to this route using Postman without any error.
Please correct my mistake. After adding:
pushNewPost(newPost) {
console.log("here is the new post", newPost);
let headers = new HttpHeaders({
'Content-Type': 'application/json',
});
let options = { headers: headers };
return this._http.post<any>(this._contributeUrl, newPost);
}
I'm getting this:

Answer 1

Seems like you are not sending in the headers from angular. Make the following changes:
pushNewPost(newPost) {
// adding the headers
const headers = new HttpHeaders({
'Content-Type': 'application/json',
});
const options = { headers: headers };
return this._http.post<any>(this._contributeUrl, newPost, options);
}