Angular Operações de Dados Remotos de Grade Hierárquica

    O Ignite UI for Angular Hierarchical Grid suporta operações remotas de dados, como virtualização remota, classificação remota, filtragem remota e outras. Isso permite que o desenvolvedor execute essas tarefas em um servidor, recupere os dados produzidos e os exiba na Grade Hierárquica.

    Por padrão, a Grade Hierárquica usa sua própria lógica para executar operações de dados. Você pode executar essas tarefas remotamente e alimentar os dados resultantes para a Grade Hierárquica, aproveitando certas entradas e eventos, que são expostos pela Grade Hierárquica.

    Unique Column Values Strategy

    The list items inside the Excel Style Filtering dialog represent the unique values for the respective column. The Hierarchical Grid generates these values based on its data source by default. In case of remote filtering, the grid data does not contain all the data from the server. In order to provide the unique values manually and load them on demand, we can take advantage of the Hierarchical Grid's uniqueColumnValuesStrategy input. This input is actually a method that provides three arguments:

    • column: a respectiva instância da coluna.
    • filteringExpressionsTree: a árvore de expressões de filtragem, que é reduzida com base na respectiva coluna.
    • done- Retorno de chamada que deve ser chamado com os valores de coluna recém-gerados quando eles são recuperados do servidor.

    O desenvolvedor pode gerar manualmente os valores de coluna exclusivos necessários com base nas informações, fornecidas pela coluna e pelos argumentos filteringExpressionsTree e, em seguida, invocar o retorno de chamada done.

    Note

    When the uniqueColumnValuesStrategy input is provided, the default unique values generating process in the excel style filtering will not be used.

    <igx-hierarchical-grid #hierarchicalGrid [primaryKey]="'Artist'" [data]="data" [filterMode]="'excelStyleFilter'"
                       [uniqueColumnValuesStrategy]="singersColumnValuesStrategy">
    ...
    <igx-row-island [primaryKey]="'Album'" [allowFiltering]="true" [filterMode]="'excelStyleFilter'"
                    [uniqueColumnValuesStrategy]="albumsColumnValuesStrategy">
        ...
    </igx-row-island>
</igx-hierarchical-grid>

    public singersColumnValuesStrategy = (column: ColumnType,
                                      columnExprTree: IFilteringExpressionsTree,
                                      done: (uniqueValues: any[]) => void) => {
// Get specific column data for the singers.
this.remoteValuesService.getColumnData(
    null, 'Singers', column, columnExprTree, uniqueValues => done(uniqueValues));
}

public albumsColumnValuesStrategy = (column: ColumnType,
                                     columnExprTree: IFilteringExpressionsTree,
                                     done: (uniqueValues: any[]) => void) => {
// Get specific column data for the albums of a specific singer.
const parentRowId = (column.grid as any).foreignKey;
this.remoteValuesService.getColumnData(
    parentRowId, 'Albums', column, columnExprTree, uniqueValues => done(uniqueValues));
}

    Unique Column Values Strategy Demo

    In order to provide a custom loading template for the excel style filtering, we can use the igxExcelStyleLoading directive:

    <igx-hierarchical-grid [data]="data" [filterMode]="'excelStyleFilter'" [uniqueColumnValuesStrategy]="columnValuesStrategy">
    ...
    <ng-template igxExcelStyleLoading>
        Loading ...
    </ng-template>
</igx-hierarchical-grid>

    Remote Paging

    O recurso de paginação pode operar com dados remotos. Para demonstrar isso, vamos primeiro declarar nosso serviço que será responsável pela busca de dados. Precisaremos da contagem de todos os itens de dados para calcular a contagem de páginas. Essa lógica será adicionada ao nosso serviço.

    @Injectable()
export class RemotePagingService {
    public remoteData: BehaviorSubject<any[]>;
    public dataLenght: BehaviorSubject<number> = new BehaviorSubject(0);
    public url = 'https://www.igniteui.com/api/products';

    constructor(private http: HttpClient) {
        this.remoteData = new BehaviorSubject([]) as any;
    }

    public getData(index?: number, perPage?: number): any {
        let qS = '';

        if (perPage) {
            qS = `?$skip=${index}&$top=${perPage}&$count=true`;
        }

        this.http
            .get(`${this.url + qS}`).pipe(
                map((data: any) => data)
            ).subscribe((data) => this.remoteData.next(data));
    }

    public getDataLength(): any {
        return this.http.get(this.url).pipe(
            map((data: any) => data.length)
        );
    }
}

    Após declarar o serviço, precisamos criar um componente, que será responsável pela construção da Grade Hierárquica e assinatura de dados.

    export class HGridRemotePagingSampleComponent implements OnInit, AfterViewInit, OnDestroy {
    public data: BehaviorSubject<any> = new BehaviorSubject([]);
    private _dataLengthSubscriber;

    constructor(private remoteService: RemotePagingService) {}

    public ngOnInit() {
        this.data = this.remoteService.remoteData.asObservable();

        this._dataLengthSubscriber = this.remoteService.getDataLength().subscribe((data) => {
            this.totalCount = data;
            this.grid1.isLoading = false;
        });
    }

    public ngOnDestroy() {
        if (this._dataLengthSubscriber) {
            this._dataLengthSubscriber.unsubscribe();
        }
    }
}

    Now we can choose between setting-up our own custom paging template or using the default one that the igx-paginator provides. Let's first take a look what is necessary to set-up remote paging by using the default paging template.

    Remote paging with default template

    If you want to use the default paging template you need to set the Paginator's totalRecords property, only then the grid will be able to calculate the total page number based on total remote records. When performing a remote pagination the Paginator will pass to the Grid only the data for the current page, so the grid will not try to paginate the provided data source. That's why we should set Grid's pagingMode property to GridPagingMode.remote. Also it is necessary to either subscribe to pagingDone or perPageChange events in order to fetch the data from your remote service, it depends on the use case which event will be used.

    <igx-hierarchical-grid #hierarchicalGrid [primaryKey]="'CustomerID'" [pagingMode]="mode">
    <igx-column field="CustomerID"></igx-column>
    ...
    <igx-paginator [(page)]="page" [(perPage)]="perPage" [totalRecords]="totalCount"
        (pagingDone)="paginate($event.current)" (perPageChange)="getFirstPage()">
    </igx-paginator>
</igx-hierarchical-grid>

    public totalCount = 0;
public data: Observable<any[]>;
public mode = GridPagingMode.remote;
public isLoading = true;
@ViewChild('grid1', { static: true }) public grid1: IgxGridComponent;

private _dataLengthSubscriber;

public set perPage(val: number) {
    this._perPage = val;
    this.paginate(0);
}

public ngOnInit() {
    this.data = this.remoteService.remoteData.asObservable();

    this._dataLengthSubscriber = this.remoteService.getDataLength().subscribe((data: any) => {
        this.totalCount = data;
        this.grid1.isLoading = false;
    });
}

public ngAfterViewInit() {
    const skip = this.page * this.perPage;
    this.remoteService.getData(skip, this.perPage);
}

public paginate(page: number) {
    this.page = page;
    const skip = this.page * this.perPage;
    const top = this.perPage;

    this.remoteService.getData(skip, top);
}

    Remote Paging with custom igx-paginator-content

    When we define a custom paginator content we need to define the content in a way to get the data only for the requested page and to pass the correct skip and top parameters to the remote service according to the selected page and items perPage. We are going to use the <igx-paginator> in order to ease our example configuration, along with the IgxPageSizeSelectorComponent and IgxPageNavigationComponent that were introduced - igx-page-size will add the per page dropdown and label and igx-page-nav will add the navigation action buttons and labels.

    <igx-paginator #paginator
    [totalRecords]="totalCount"
    [(perPage)]="perPage"
    [(page)]="page"
    [selectOptions]="selectOptions"
    (pageChange)="paginate($event)"
    (perPageChange)="perPageChange($event)">
    <igx-paginator-content>
        <igx-page-size></igx-page-size>
        [This is my custom content]
        <igx-page-nav></igx-page-nav>
    </igx-paginator-content>
</igx-paginator>

    @ViewChild('hierarchicalGrid', { static: true }) public hierarchicalGrid: IgxHierarchicalGridComponent;

public ngOnInit(): void {
    this._dataLengthSubscriber = this.remoteService.getDataLength(
        { parentID: null, rootLevel: true, key: 'Customers' }).subscribe((length) => {
            this.totalCount = length;
        });
}

public ngAfterViewInit() {
    this.hierarchicalGrid.isLoading = true;
    this._dataSubscriber = this.remoteService.getData({parentID: null, rootLevel: true, key: 'Customers' }, 0, this.perPage)
        .subscribe((data) => {
            this.hierarchicalGrid.isLoading = false;
            this.data.next(data);
        },(error) => {
                this.hierarchicalGrid.emptyGridMessage = error.message;
                this.hierarchicalGrid.isLoading = false;
                this.hierarchicalGrid.cdr.detectChanges();
            }
        );
}
    Note

    In order the Remote Paging to be configured properly a GridPagingMode.Remote should be set:

    <igx-hierarchical-grid #hierarchicalGrid [data]="data | async" [primaryKey]="'CustomerID'"
    [height]="'550px'" [width]="'100%'" [pagingMode]="mode"></igx-hierarchical-grid>
...
public mode = GridPagingMode.Remote;

    A última etapa será declarar o conteúdo do paginador com base em seus requisitos.

    <igx-paginator-content>
    <igx-page-size></igx-page-size>
    [This is my custom content]
    <igx-page-nav></igx-page-nav>
</igx-paginator-content>

    Após todas as alterações acima, o seguinte resultado será alcançado.

    Known Issues and Limitations

    • When the grid has no primaryKey set and remote data scenarios are enabled (when paging, sorting, filtering, scrolling trigger requests to a remote server to retrieve the data to be displayed in the grid), a row will lose the following state after a data request completes:
      • Seleção de linha
      • Expandir/recolher linha
      • Edição de linha
      • Fixação de linha
    • In remote data scenarios, when the grid has a primaryKey set, rowSelectionChanging.oldSelection event argument will not contain the full row data object for the rows that are currently out of the data view. In this case, rowSelectionChanging.oldSelection object will contain only one property, which is the primaryKey field. For the rest of the rows, currently in the data view, rowSelectionChanging.oldSelection will contain the whole row data.

    API References

    Additional Resources

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