HTTP service Authorization wrapper + JSON payload

request.service.ts

import { Injectable } from '@angular/core'
import { Http, Headers, RequestOptions, Response } from '@angular/http'
import { Observable } from 'rxjs'
import 'rxjs/add/operator/map'

/**
 * Usage:
 *
 *    export class MyAuthService {
 *      constructor (private request: RequestService) {
 *        request.tokenGetter = (() => sessionStorage.getItem('call_your_token'))
 *      }
 *
 *      login (username: string, password: string) {
 *        this.request.post('/auth', { username, password }).map((response: Response) => {
 *          // handle your data...
 *        })
 *      }
 *    }
 */

@Injectable()
export class RequestService {
  tokenGetter: Function

  private API_URL = 'http://localhost/api'

  private options = new RequestOptions({
    headers: new Headers({
      'Content-Type': 'application/json'
    })
  })

  constructor (protected $http: Http) {}

  baseUrl (url: string) {
    return `${this.API_URL}${url}`
  }

  // Performs a request with `get` http method.
  get (url: string, options: RequestOptions = this.options): Observable<Response> {
    return this.$http.get(this.baseUrl(url), this.wrapAuthorization(options))
  }

  // Performs a request with `post` http method.
  post (url: string, body: any, options: RequestOptions = this.options): Observable<Response> {
    return this.$http.post(this.baseUrl(url), JSON.stringify(body), this.wrapAuthorization(options))
  }

  // Performs a request with `put` http method.
  put (url: string, body: any, options: RequestOptions = this.options): Observable<Response> {
    return this.$http.put(this.baseUrl(url), JSON.stringify(body), this.wrapAuthorization(options))
  }

  // Performs a request with `delete` http method.
  delete (url: string, options: RequestOptions = this.options): Observable<Response> {
    return this.$http.delete(this.baseUrl(url), this.wrapAuthorization(options))
  }

  private wrapAuthorization (options: RequestOptions): RequestOptions {
    const token: string = this.tokenGetter()

    if (token) {
      options.headers = options.headers || new Headers()
      options.headers.set('Authorization', `Bearer ${token}`)
    }

    return options
  }
}