Angular2无法从Service获取模拟数据

Question

UPDATE: sorry i copied the wrong version of my code: i did call then inside the service as shown now.

I'm creating a Service that provides mock data (following a similar structure as here ) but cannot get data for some reason.

snippet from AppComponent

export class AppComponent implements OnInit{
  ngOnInit(){
    this.getData();
  }


  constructor(private _dataService: DataService){ }

  getData(){
      console.log('get data called');
      var data = this._dataService.getData();
      console.log('data type is '+typeof(data));
      console.log('data key is ');
      for(var k in data){
        console.log(k);
      }

DataService is as follows:

import {Injectable} from 'angular2/core';
import {MOCK_DATA} from './mock-data';

@Injectable()
export class DataService{
  getData(){
    return Promise.resolve(MOCK_DATA).then(data => data);
  }
}

mock data is:

export var MOCK_DATA = {
  "apple": [
    {"taste": "apple", "really": false},
    {"taste": "random", "really": true},
  ],
  "orange": [
    {"taste": "orange", "really": false},
    {"taste": "random", "really": true},
  ],
}

however the console.log results are:

get data called
app.component.ts:46 data type object
app.component.ts:47 data key 
app.component.ts:49 __zone_symbol__state
app.component.ts:49 __zone_symbol__value
app.component.ts:49 then
app.component.ts:49 catch

Answer 1

You need to call the then method on the returned promise by the getData method to be able to receive the data:

getData() {
  console.log('get data called');
  this._dataService.getData().then(data => {
    // Handle the data

    // For example
    console.log('data type is '+typeof(data));
    console.log('data key is ');
    for(var k in data){
      console.log(k);
    }
  });
}

The then method must be used within the component and not in the service.

Your service should be:

@Injectable()
export class RBACService{
  getData(){
    return Promise.resolve(MOCK_DATA);
  }
}

instead of

@Injectable()
export class RBACService{
  getData(){
    return Promise.resolve(MOCK_DATA).then(data => data);
  }
}

Answer 2

I think you are missing some important part of your code in the decorator for the AppComponent , something like this:

import { Component, OnInit } from 'angular2/core';
import { RBACService } from './(serviceName).service';

@Component({
    selector: 'my-app',
    template: `whatever...`,
    providers: [RBACService]
})
export class AppComponent implements OnInit {

Where (serviceName) should be the file name of your inyectable service and whatch out cause you inyected it at the constructor as DataService and it's actually called RBACService ...