Working with Lists

ListService is a utility service to provide an easy pagination, sorting, and search implementation.

Getting Started

ListService is not provided in root. The reason is, this way, it will clear any subscriptions on component destroy. You may use the optional LIST_QUERY_DEBOUNCE_TIME token to adjust the debounce behavior.

import { ListService } from '@abp/ng.core';
import { BookDto } from '../models';
import { BookService } from '../services';

@Component({
  /* class metadata here */
  providers: [
    // [Required]
    ListService,

    // [Optional]
    // Provide this token if you want a different debounce time.
    // Default is 300. Cannot be 0. Any value below 100 is not recommended.
    { provide: LIST_QUERY_DEBOUNCE_TIME, useValue: 500 },
  ],
  template: `
    
  `,
})
class BookComponent {
  items: BookDto[] = [];
  count = 0;

  constructor(
    public readonly list: ListService,
    private bookService: BookService,
  ) {}

  ngOnInit() {
    // A function that gets query and returns an observable
    const bookStreamCreator = query => this.bookService.getList(query);

    this.list.hookToQuery(bookStreamCreator).subscribe(
      response => {
        this.items = response.items;
        this.count = response.count;
        // If you use OnPush change detection strategy,
        // call detectChanges method of ChangeDetectorRef here.
      }
    ); // Subscription is auto-cleared on destroy.
  }
}

Noticed list is public and readonly? That is because we will use ListService directly in the component's template. That may be considered as an anti-pattern, but it is much quicker to implement. You can always use public component members to expose the ListService instance instead.

Bind ListService to ngx-datatable like this:

<ngx-datatable
  [rows]="items"
  [count]="count"
  [list]="list"
  default
>
  <!-- column templates here -->
</ngx-datatable>

Usage with Observables

You may use observables in combination with AsyncPipe of Angular instead. Here are some possibilities:

  book$ = this.list.hookToQuery(query => this.bookService.getListByInput(query));

<!-- simplified representation of the template -->

<ngx-datatable
  [rows]="(book$ | async)?.items || []"
  [count]="(book$ | async)?.totalCount || 0"
  [list]="list"
  default
>
  <!-- column templates here -->
</ngx-datatable>

<!-- DO NOT WORRY, ONLY ONE REQUEST WILL BE MADE -->

...or...

  @Select(BookState.getBooks)
  books$: Observable<BookDto[]>;

  @Select(BookState.getBookCount)
  bookCount$: Observable<number>;

  ngOnInit() {
    this.list.hookToQuery((query) => this.store.dispatch(new GetBooks(query))).subscribe();
  }

<!-- simplified representation of the template -->

<ngx-datatable
  [rows]="(books$ | async) || []"
  [count]="(bookCount$ | async) || 0"
  [list]="list"
  default
>
  <!-- column templates here -->
</ngx-datatable>

We do not recommend using NGXS store for CRUD pages, unless your application needs to share list information between components or use it later on in another page.

How to Refresh Table on Create/Update/Delete

ListService exposes a get method to trigger a request with the current query. So, basically, whenever a create, update, or delete action resolves, you can call this.list.get(); and it will call hooked stream creator again.

  this.bookService.createByInput(form.value)
    .subscribe(() => {
      this.list.get();

      // Other subscription logic here
    });

...or...

  this.store.dispatch(new DeleteBook(id)).subscribe(this.list.get);

We donot recommend using NGXS store for CRUD pages, unless your application needs to share list information between components or use it later on in another page.

How to Implement Server-Side Search in a Table

ListService exposes a filter property that will trigger a request with the current query and the given search string. All you need to do is to bind it to an input element with two-way binding.

<!-- simplified representation -->

<input type="text" name="search" [(ngModel)]="list.filter">

Breaking Change with ABP v3.0

We had to modify the ListService to make it work with ngx-datatable. Previously, the minimum value for page property was 1 and you could use it like this:

<!-- other bindings are hidden in favor of brevity -->
<abp-table
  [(page)]="list.page"
></abp-table>

As of v3.0, with ngx-datatable, the page property has to be set as 0 for inital page. Therefore, if you used ListService on your tables before and are going to keep abp-table, you need to make the following change:

<!-- other bindings are hidden in favor of brevity -->
<abp-table
  [page]="list.page + 1"
  (pageChange)="list.page = $event - 1"
></abp-table>

Important Note: The abp-table is not removed, but is deprecated and will be removed in the future. Please consider switching to ngx-datatable.

What's Next?

• Easy *ngFor trackBy