import React, { Component } from 'react';
import * as firebase from 'firebase';

var config = {
    apiKey: "API_KEY",
    authDomain: "ds-neighborhood-map.firebaseapp.com",
    databaseURL: "https://ds-neighborhood-map.firebaseio.com",
    projectId: "ds-neighborhood-map",
    storageBucket: "",
    messagingSenderId: "892195464936"
  };

firebase.initializeApp(config);
var db = firebase.firestore();
const settings = {timestampsInSnapshots: true};
db.settings(settings);


export default class Firebase extends Component {

    constructor(props) {
        super(props);

      }

    static getAll(colName) {
        return new Promise((resolve, reject) => {

            db.collection(colName).get().then(response => {
                if(response.size) {
                    var responseData = [];
                    response.forEach(e => {
                        responseData.push(e.data())
                    })
                    resolve(responseData);
                }else{
                    reject({'error': 'Can't execute a request. The database is empty!'});
                }
            }).catch(err => {
                reject({'error': 'Network error! Can't connect to the DB'});
            });
        })
    }

    render() {
        return;
    }
  }

export const getAll = Firebase.getAll;

import React, { Component } from 'react';
import logo from './logo.svg';
import './App.css';

import * as firebase from './Firebase'; // компонент БД

class App extends Component {

  render() {
       // использование метода импортированного компонента
       firebase.getAll('locations').then(response => {
         console.log(response);
       });



    return (
      <div className="App">
        <header className="App-header">
          <img src={logo} className="App-logo" alt="logo" />
          <h1 className="App-title">Welcome to React</h1>
        </header>
        <p className="App-intro">
          To get started, edit <code>src/App.js</code> and save to reload.
        </p>
      </div>
    );
  }
}

export default App;