angularangular-materialazure-table-storageazure-tablequerymat-pagination

Angular MatPaginator and Azure Table Storage


I'm trying to implement an Angular material table with pagination, that is connected to the backend, that retrieves data from Azure Table Storage.

I know, that Table Storage supports ExecuteQuerySegmentedAsync, which returns TableContinuationToken. It looks fine. So on the frontend, I get something like this:

interface IPagedResult<T> {
    items: T[];
    isFinalPage: boolean;
    continuationToken: string;
}

interface ILog {
    enqueuedDate: string;
    ...
}

Somewhere in component.ts:


private logsTableSource: MatTableDataSource<ILog>;
@ViewChild(MatPaginator)paginator: MatPaginator;

ngAfterViewInit() {
   myService.GetRecords(this.paginator.pageSize)
            .subscribe(
               (res: IPagedResult<ILog>) => {
                    this.logsTableSource = new MatTableDataSource<ILog>(res.items);
               });
}

Now I'm wondering, how to get the number of pages? And let the server know what specific page I want?

continuationToken looks like this: enter image description here

In fact, what I can do with this continuationToken?

For better understanding this is how the table looks like: enter image description here


Solution

  • As @rickvdbosch said, TableContinuationToken expects only moving forward. After some changes in the paginator I can move only forward and backward. Looks quite good and works for me: enter image description here

    If someone is interested. Here are the changes:

    1. Implement your own MatPaginatorIntl to remove pages label. My looks like this:
    @Injectable()
    export class LogsPaginator extends MatPaginatorIntl {
        public getRangeLabel = function (page: number, pageSize: number, length: number) {
            return '';
        };
    }
    
    1. Cache items, that you have previously loaded since we can move ONLY forward with TableContinuationToken. Your component.ts should look something like this:
    export class LogsComponent {
      // As table storage does not support paging per index, we should cache already loaded logs and use continuation token if needed.
    
      private cachedLogs: ILog[] = [];
      private cachedIndexes: number[] = [];
      private continuationToken = '';
    
      ngOnInit() {
        this.paginator.page.subscribe(this.pageChanged.bind(this));
      }
    
      async ngAfterViewInit() {
        await this.loadLogs();
      }
    
      private async pageChanged(event: PageEvent) {
        if (event.previousPageIndex < event.pageIndex && this.cachedIndexes.indexOf(event.pageIndex) === -1) {
          await this.loadLogs();
        } else {
          this.redrawTable();
        }
      }
    
      private redrawTable() {
        const start = this.paginator.pageIndex * this.paginator.pageSize;
        const end = start + this.paginator.pageSize;
        this.logsTableSource.data = this.cachedLogs.slice(start, end);
      }
    
    
      private async loadLogs() {
          const res = await this.myService.GetLogs(this.paginator.pageSize, this.continuationToken).toPromise();
          this.cachedIndexes.push(this.paginator.pageIndex);
          this.cachedLogs.push(...res.items);
          this.paginator.length = res.isFinalPage ? this.cachedLogs.length : this.cachedLogs.length + 1;
          this.continuationToken = res.continuationToken;
    
          this.redrawTable();
      }
    }