StackOverflow上有個朋友遇到了一個問題：

在 feature module 裡，對一個 Component 進行延遲載入：

注意上圖第 9 行，匯入了 CommonModule.

這個被延遲載入的 Component 的模板檔案裡，使用到了 async 這個 pipe，其實現在 CommonModule 裡。然而，因為該 module 被延遲載入，因此並未靜態地定義在 feature module 的 declarations 模組裡。所以，該 Component 被載入的時候，其上下文無法訪問到 async pipe.

所以，最後會出現執行時錯誤：

ERROR Error: The pipe 'async' could not be found!

解決方案，我已經回覆在 StackOverflow 裡了：

https://stackoverflow.com/questions/68258149/the-pipe-async-could-not-be-found-in-spartacus-lazy-loading-of-cms-components

在被延遲載入的 Component 裡，將其所屬的 feature module 的定義人工加上即可：

import { ChangeDetectionStrategy, Component, NgModule } from '@angular/core';
import { Product, provideDefaultConfig, CmsConfig } from '@spartacus/core';
import { CurrentProductService, MediaModule, OutletModule, CarouselModule } from '@spartacus/storefront';
import { BehaviorSubject, combineLatest, Observable, of } from 'rxjs';
import { distinctUntilChanged, filter, map, tap } from 'rxjs/operators';
import { CommonModule } from '@angular/common';
import { RouterModule } from '@angular/router';

@Component({
  selector: 'app-product-images',
  templateUrl: './razer-product-images.component.html',
  changeDetection: ChangeDetectionStrategy.OnPush,
})
export class CustomProductImagesComponent {
  private mainMediaContainer = new BehaviorSubject(null);

  private product$: Observable<Product> = this.currentProductService
    .getProduct()
    .pipe(
      filter(Boolean),
      distinctUntilChanged(),
      tap((p: Product) => {
        this.mainMediaContainer.next(p.images?.PRIMARY ? p.images.PRIMARY : {});
      })
    );

  thumbs$: Observable<any[]> = this.product$.pipe(
    map((p: Product) => this.createThumbs(p))
  );

  mainImage$ = combineLatest([this.product$, this.mainMediaContainer]).pipe(
    map(([, container]) => container)
  );

  constructor(private currentProductService: CurrentProductService) {}

  openImage(item: any): void {
    this.mainMediaContainer.next(item);
  }

  isActive(thumbnail): Observable<boolean> {
    return this.mainMediaContainer.pipe(
      filter(Boolean),
      map((container: any) => {
        return (
          container.zoom &&
          container.zoom.url &&
          thumbnail.zoom &&
          thumbnail.zoom.url &&
          container.zoom.url === thumbnail.zoom.url
        );
      })
    );
  }

  /** find the index of the main media in the list of media */
  getActive(thumbs: any[]): Observable<number> {
    return this.mainMediaContainer.pipe(
      filter(Boolean),
      map((container: any) => {
        const current = thumbs.find(
          (t) =>
            t.media &&
            container.zoom &&
            t.media.container &&
            t.media.container.zoom &&
            t.media.container.zoom.url === container.zoom.url
        );
        return thumbs.indexOf(current);
      })
    );
  }

  /**
   * Return an array of CarouselItems for the product thumbnails.
   * In case there are less then 2 thumbs, we return null.
   */
  private createThumbs(product: Product): Observable<any>[] {
    if (
      !product.images ||
      !product.images.GALLERY ||
      product.images.GALLERY.length < 2
    ) {
      return [];
    }

    return (<any[]>product.images.GALLERY).map((c) => of({ container: c }));
  }
}

@NgModule({
  imports: [
    CommonModule,
    RouterModule,
    MediaModule,
    OutletModule,
    CarouselModule
  ],
  declarations:[CustomProductImagesComponent]
})
export class CustomProductImagesModule {}
 

更多Jerry的原創文章，盡在："汪子熙":