Post operation not working with Angular 4

Question

I'm learning Node.JS with Angular 4. I build a sample Node API for simple GET/POST request. My GET operation works fine and I am able to fetch data in Angular. My OST operation isn't getting called at all from Angular. If I use Postman, I'm able to call POST successfully and data also gets inserted in database.

Here is my sample code for Node POST:

app.post('/groups', function (req, res, next){


res.header("Access-Control-Allow-Origin", "*");
res.header("Access-Control-Allow-Headers", "X-Requested-With, Content-Type");
res.header("Access-Control-Allow-Methods", "GET, POST","PUT");

console.log('Request received with body' + req.body);
//DEV AWS MySQL
var mysql = require('mysql');

var connection = mysql.createConnection({
                      host     : 'xxxxxxx',
                      user     : 'xxxxxxx',
                      password : 'xxxxxxx',
                      database : 'xxxxxxx',
                      port     : 3306
});
connection.connect();

connection.query('CALL storedprocedure(?, ?, ?, ?, ?, ?)', [req.body.group_avatar_image,req.body.name,req.body.display_name,req.body.unique_id,req.body.description,req.body.adzone], function (err, results, fields){

    if (err)
        res.send(results);

    //res.status(201).send("Groups created successfully");
    res.status(201).send(results[0]);
});

This works fine with Postman and I get 201.

Here is my Angular 4 code:

    import { Injectable } from '@angular/core';
import { Http, Response,RequestOptions, Request, RequestMethod, Headers} from '@angular/http';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/catch';
import 'rxjs/add/operator/do';
import { Group } from './group';

@Injectable()
export class GroupsService{

    private _GroupsUrl = 'http://localhost:5000/api/groups';
    constructor(private _http: Http){};

    getGroups(): Observable<Group[]> {
        let headers = new Headers({ 'Content-Type': 'application/json' });
        headers.append('Accept', 'application/json');
        headers.append('Access-Control-Allow-Methods', 'POST, GET, OPTIONS, DELETE, PUT');
        headers.append('Access-Control-Allow-Origin', '*');
        //headers.append('Access-Control-Allow-Headers', "X-Requested-With, Content-Type, Origin, Authorization, Accept, Client-Security-Token, Accept-Encoding");
        let options = new RequestOptions({ method: RequestMethod.Post, headers: headers,  url:this._GroupsUrl  });    

        //debugger;
        return this._http.get(this._GroupsUrl)
                .map((Response: Response) => <Group[]>Response.json()[0])
                //.do(data => console.log ('ALL: ' + JSON.stringify(data)))
                .catch(this.handleError);
    }

    CreateGroup(GroupM): Observable<string>{

        let headers = new Headers({ 'Content-Type': 'application/json' });
            headers.append('Access-Control-Allow-Methods', 'POST, GET, OPTIONS, DELETE, PUT, OPTIONS');
            headers.append('Access-Control-Allow-Origin', 'http://localhost:4200');
            headers.append('Access-Control-Allow-Headers', "X-Requested-With, Content-Type");
        //let options = new RequestOptions({ method: RequestMethod.Post, headers: headers, body:JSON.stringify(GroupM),  url:this._GroupsUrl  });    
        let options = new RequestOptions({ method: RequestMethod.Post});    

        console.log('Calling ' + this._GroupsUrl + ' with body as :' + JSON.stringify(GroupM) + ' and request options are : ' + JSON.stringify(options));

        var req = new Request(options.merge({
        url: this._GroupsUrl
        }));

        debugger;
        //return this._http.post(this._GroupsUrl,GroupM)
        return this._http.post(req.url,JSON.stringify(GroupM),options)
                     .map(res => res.json())
                     .do(data => console.log ('ALL: ' + JSON.stringify(data)))
                     .catch(this.handleError);
    }

    private handleError(error:Response) {
        console.error(error);
        return Observable.throw(error.json().error || 'Server Error');
    }
}

What is wrong here?

Answer 1

Don't stringify the POST data in HTTP POST. Simply pass the object.

Answer 2

Finally able to resolve it using promise and it resolves the issue. Not sure what exactly is the issue with observable.

>  CreateGroup(GroupObj:Group) : Promise<Group>{
        return this._http
                .post(this._GroupsUrl,JSON.stringify(GroupObj),{headers: this.headers})
                .toPromise()
                .then(res => res.json().data as Group)
                .catch(this.handleError);
    }