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import { DataSource } from '@angular/cdk/collections';
import { MatPaginator, MatSort } from '@angular/material';
import { map } from 'rxjs/operators';
import { Observable, of as observableOf, merge } from 'rxjs';
/**
* Data source for the NgxDataTable view. This class should
* encapsulate all logic for fetching and manipulating the displayed data
* (including sorting, pagination, and filtering).
*/
export class NgxDataTableDataSource extends DataSource<any> {
private data: any[];
constructor(private paginator: MatPaginator, private _data: any[], private sort: MatSort) {
super();
this.data = _data;
}
/**
* Connect this data source to the table. The table will only update when
* the returned stream emits new items.
* @returns A stream of the items to be rendered.
*/
connect(): Observable<any[]> {
// Combine everything that affects the rendered data into one update
// stream for the data-table to consume.
const dataMutations = [
observableOf(this.data),
this.paginator.page,
this.sort.sortChange
];
// Set the paginators length
this.paginator.length = this.data.length;
return merge(...dataMutations).pipe(map(() => {
return this.getPagedData(this.getSortedData([...this.data]));
}));
}
/**
* Called when the table is being destroyed. Use this function, to clean up
* any open connections or free any held resources that were set up during connect.
*/
disconnect() {}
/**
* Paginate the data (client-side). If you're using server-side pagination,
* this would be replaced by requesting the appropriate data from the server.
*/
private getPagedData(data: any[]) {
const startIndex = this.paginator.pageIndex * this.paginator.pageSize;
return data.splice(startIndex, this.paginator.pageSize);
}
/**
* Sort the data (client-side). If you're using server-side sorting,
* this would be replaced by requesting the appropriate data from the server.
*/
private getSortedData(data: any[]) {
if (!this.sort.active || this.sort.direction === '') {
return data;
}
return data.sort((a, b) => {
const isAsc = this.sort.direction === 'asc';
if (isNaN(a[this.sort.active])) {
return compare(a[this.sort.active], b[this.sort.active], isAsc);
} else {
return compare(+a[this.sort.active], +b[this.sort.active], isAsc);
}
});
}
}
/** Simple sort comparator for example ID/Name columns (for client-side sorting). */
function compare(a, b, isAsc) {
return (a < b ? -1 : 1) * (isAsc ? 1 : -1);
}
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