persisting songs ins show

src/app/modules/guest/guest.component.ts

@@ -1,43 +1,26 @@
-import {Component, OnInit} from '@angular/core';
+import {Component} from '@angular/core';
 import {SongService} from '../songs/services/song.service';
 import {GlobalSettingsService} from '../../services/global-settings.service';
 import {Observable} from 'rxjs';
 import {filter, map, switchMap} from 'rxjs/operators';
 import {ShowSongService} from '../shows/services/show-song.service';
 import {GlobalSettings} from '../../services/global-settings';
-import {Song} from '../songs/services/song';
 
 @Component({
   selector: 'app-guest',
   templateUrl: './guest.component.html',
   styleUrls: ['./guest.component.less'],
 })
-export class GuestComponent implements OnInit {
-  public songs$: Observable<Observable<string>[]> | null = null;
+export class GuestComponent {
+  public songs$: Observable<string[]> = this.globalSettingsService.get$.pipe(
+    filter(_ => !!_),
+    map(_ => _ as GlobalSettings),
+    map(_ => _.currentShow),
+    switchMap(_ => this.showSongService.list$(_)),
+    filter(_ => !!_),
+    map(_ => _),
+    map(_ => _.sort((x, y) => x.order - y.order).map(showSong => showSong.text))
+  );
 
-  public constructor(
-    private songService: SongService,
-    private globalSettingsService: GlobalSettingsService,
-    private showSongService: ShowSongService
-  ) {}
-
-  public ngOnInit(): void {
-    this.songs$ = this.globalSettingsService.get$.pipe(
-      filter(_ => !!_),
-      map(_ => _ as GlobalSettings),
-      map(_ => _.currentShow),
-      switchMap(_ => this.showSongService.list$(_)),
-      filter(_ => !!_),
-      map(_ => _),
-      map(_ =>
-        _.sort((x, y) => x.order - y.order).map(showSong =>
-          this.songService.read$(showSong.songId).pipe(
-            filter(_ => !!_),
-            map(_ => _ as Song),
-            map(song => song.text)
-          )
-        )
-      )
-    );
-  }
+  public constructor(private songService: SongService, private globalSettingsService: GlobalSettingsService, private showSongService: ShowSongService) {}
 }