angular4 http headers , How to set up?

Question

import { Injectable } from '@angular/core';
import { Http, Headers, Response, RequestOptions,  } from '@angular/http';
@Injectable()
export class RoleService {
    headers = new Headers({"Content-Type": "application/json"});
     options = new RequestOptions({ headers: this.headers });
     constructor(private http: Http) {  }

    getRoleList(data) {
         return this.http.post('http://192.168.10.178:9080/role/getRole', data, this.options)
                .toPromise()
                .then(res => res.json().data)
                .then(data => { return data; });
    }
}

https://i.sstatic.net/nPiK8.png

Help me!! How to solve this ???

Answer 1

Try

export class RoleService {
  options: RequestOptions;

  constructor(private http: Http) {
    let headers: any = new Headers();
    headers.append('Content-Type', 'application/json');

    this.options = new RequestOptions({ headers: headers });
  }

// ........

Answer 2

Its might be fix your issue

import { Injectable } from '@angular/core';
import { Http, Headers, Response, RequestOptions,  } from '@angular/http';
@Injectable()
export class RoleService {
     constructor(private http: Http) {  }

    getRoleList(data) {
     let headers = new Headers({"Content-Type": "application/json"});
     let options = new RequestOptions({ headers: headers });
         return this.http.post('http://192.168.10.178:9080/role/getRole', data, this.options)
                .toPromise()
                .then(res => res.json().data)
                .then(data => { return data; });
}}

Answer 3

After the version of Angular 4.3, HttpClientModule was introduced along with HttpClient, HttpHeaders, HttpParams and HttpRequest and some of the method has been deprecated such as RequestOptions.

You can use HttpClientModule from @angular/common/http.

import { HttpClient, HttpRequest, HttpParams, HttpHeaders } from '@angular/common/http';
export class AppComponent {
    constructor(private http: HttpClient){}
    headers = new HttpHeaders({"Content-Type": "application/json"});

    callAPI(){
         return this.http.get(URL,{headers}).subscribe(data=>{
             console.log(data);
         });
    }
}

You can also refer :- https://angular.io/api/common/http/