data.service.ts

import 'rxjs/add/operator/catch';
import 'rxjs/add/operator/map';
import 'rxjs/add/observable/throw';

import { Observable } from 'rxjs/Observable';

import { HttpClient, HttpHeaders } from '@angular/common/http';
import { Injectable } from '@angular/core';

import { AppError } from '../errors/app-error';
import { BadInput } from '../errors/bad-input';
import { NotFoundError } from '../errors/not-found-error';

@Injectable()
export class DataService {
    constructor(private url: string, private http: HttpClient) { }

    getAll() {
        return this.http.get(this.url)
            .map(response => response)
            .catch(this.handleError);
    }

    create(resource) {
        return this.http.post(this.url, JSON.stringify(resource))
            .map(response => response)
            .catch(this.handleError);
    }

    update(resource) {
        return this.http.patch(this.url + '/' + resource.id, JSON.stringify(resource))
            .map(response => response)
            .catch(this.handleError);
    }

    delete(id) {
        return this.http.delete(this.url + '/' + id)
            .map(response => response)
            .catch(this.handleError);
    }

    private handleError(error: Response) {
        if (error.status === 400) {
            return Observable.throw(new BadInput(error.json()));
        }

        if (error.status === 404) {
            return Observable.throw(new NotFoundError());
        }

        return Observable.throw(new AppError(error));
    }
}

vendor-invoices.service.ts

import { HttpClient } from '@angular/common/http';
import { Injectable } from '@angular/core';

import { environment } from '../../../environments/environment';
import { DataService } from '../../shared/services/data.service';

@Injectable()
export class VendorInvoicesService extends DataService {

    constructor(http: HttpClient) {
        super(`${environment.baseUrl}/api/vendor_invoices`, http);
    }

}