Processing a complex object by http get in Angular 6

Question

I do not understand how to handle the object I subscribe to. The object is the following structure:

{
  data:{
       date: "2018-02-20 13:10:23",
       text: "Описание",
       id: 1,
       items: [
              0: {
                 date: "2018-02-20 13:10:23",
                 text: "Описание",
                 images: [
                         0: "image1.jpg",
                         1: "image2.jpg"
                         ],
                 name: "Изображения",
                 type: "images"
                 },
              1: {
                 date: "2018-02-20 13:10:23",
                 text: "Описание",
                 image: null,
                 type: "video",
                 url: "https://www.youtube.com/embed/v64KOxKVLVg"
                 }
              ]
       }
}

I make an appeal through the service:

import {HttpClient} from '@angular/common/http';
import {Injectable} from '@angular/core';
@Injectable()
export class VideoService {
    constructor(private http: HttpClient) {}

    getVideoTape() {
        return this.http.get(`http://ip_adress/api/v1/mixed_galleries/1`);
    }
}

There is an interface model:

export class VideoListModel {
    constructor(
        public created_at: string,
        public description: string,
        public id: number,
        public items: any[],
        public name: string
    ) {}
}

And I do the processing in the component:

import {Component, OnDestroy, OnInit} from '@angular/core';
import {Observable, Subscription} from 'rxjs';
import {filter} from 'rxjs/operators';
import {VideoService} from '../shared/services/video.service';
import {VideoListModel} from '../../shared/models/video-list.model';

@Component({
  selector: 'app-video-index',
  templateUrl: './video-index.component.html',
  styleUrls: ['./video-index.component.scss']
})

export class VideoIndexComponent implements OnInit, OnDestroy {
    private videoTape = [];
    private _subscription2: Subscription;

    constructor( private videoService: VideoService ) { }

  ngOnInit() {
      this._subscription2 = this.videoService.getVideoTape()
          .subscribe((data: VideoListModel[]) => {
          this.videoTape = data;
          console.log(this.videoTape);
      });
  }

    ngOnDestroy() {
        this._subscription2.unsubscribe();
    }

}

The task is to make a selection from objects by type: "video". Through AJAX + jQuery did it without problems, and in Angular I'm relatively new. Shoveled a bunch of video lessons yesterday, but nowhere are examples of filtering such complex objects.

Construction:

this._subscription2 = this.videoService.getVideoTape()
          .pipe(filter((data: VideoListModel[]) => data.items.type === 'video'))
          .subscribe((data: any) => {
              this.videoTape = data.data;
              console.log(this.videoTape);
          });

does not work. The result is an error saying "Property 'items' does not exist on type 'VideoListModel []'". Intuitively, I understand that the matter is most likely in the interface, but I can not understand how to modify the interface so that the filtering works correctly. If someone encountered filtering complex objects, tell me please how to solve this problem.

Answer 1

You don't have an array of VideoModels but an array of items in an object. Piping the whole content to a filter lets you filter items out of arrays, but you have an object. You could try the following workaround:

Create an interface like this

interface Item {
  date: Date;
  text: string;
  images: string[];
  name: string;
  type: string;
}

export interface VideoModel {
  data: {
    date: Date;
    text: string;
    id: number;
    items: Item[];
  }
}

Then you can use HttpClient in your Service as follows

import { Observable } from 'rxjs';
import { map, catchError } from 'rxjs/operators';
[...]

getVideoTape(): Observable<VideoModel> {
  return this.http.get<VideoModel>(url).pipe(
    map(model => {
      const items = model.data.items.filter(item => item.type === 'video');
      model.data.items = items;
      return model;
    }),
    catchError(error => console.error(error))
  );
}

Pay attention to your images array, as it isn't valid json, string[]? Wouldn't it be better to filter the types serverside in order to reduce traffic?