Angular2 http.post not working - node.js

Question

Service:
postJson() {
var json = JSON.stringify({
"key": "CT",
"values": ["FSP", "HMC", "PHYP","hell"]
});
let headers = new Headers({'Content-Type':'application/json'});
//let options = new RequestOptions({headers: headers});
//headers.append('Access-Control-Allow-Origin', '*');
return this._http.post('http://localhost:8080/add',json,headers)
.map(res => res.json());
}
Component:
postData;
onTestPost() {
this._httpService.postJson()
.subscribe(
data=> this.postData = JSON.stringify(data),
error=> alert(error),
() => console.log("finished")
)
}
Node.js Script
var express = require('express');
var path = require('path');
var app = express();
var fs = require("fs");
var bodyParser = require('body-parser');
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({extended: true}));
app.use("/node_modules", express.static('node_modules'));
console.log( __dirname);
app.post('/add', (req, res) => {
console.log('Received request'+JSON.stringify(req.body));
fs.writeFile(__dirname + '/CTRoot/data.json', JSON.stringify(req.body), (err) => {
//if (err) throw err;
console.log('File written to JSON.json');
res.setHeader('Access-Control-Allow-Origin', '*')
//Add as many Headers as you want to line below
//If you use "Authentication" Header, insert it like 'Content-type, Authentication'
res.setHeader('Access-Control-Allow-Headers', 'Content-type')
res.setHeader("Content-type", "application/json");
res.setHeader('Access-Control-Allow-Methods',
'GET,PUT,POST,DELETE,OPTIONS')
res.send('File written to JSON.json')
})
});
SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data
I have tried adding many headers, but it's not working.
following output is coming
File written to JSON.json
req.body is coming empty, but in web network request header and body is as expected

Answer 1

Why are you using JSON.stringify to create the request body? that makes the request body type text instead of application/json.
So try:
postJson() {
let json = {
"key": "CT",
"values": ["FSP", "HMC", "PHYP","hell"]
};
let headers = new Headers({'Content-Type':'application/json'});
return this._http.post('http://localhost:8080/add',json,headers)
.map(res => res.json());
}
I ran a quick test trying to send request body as text, where my api expects application/json, I get this error back:
{"code":500,"message":"Content type 'text/plain;charset=UTF-8' not supported"}