ExcelDataSource.FillAsync(CancellationToken) Method
Populates the ExcelDataSource in an asynchronous manner and uses the cancellationToken parameter to send the cancellation signal.
Namespace: DevExpress.DataAccess.Excel
Assembly: DevExpress.DataAccess.v20.2.dll
NuGet Packages: DevExpress.DataAccess, DevExpress.WindowsDesktop.DataAccess
Declaration
Parameters
| Name | Type | Description |
|---|---|---|
| cancellationToken | CancellationToken | A cancellation token that the task observes. |
Returns
| Type | Description |
|---|---|
| Task | A task that populates the data source. |
Remarks
Use this method to populate an Excel data source in an individual task asynchronously. Unlike the Fill() method call, FillAsync does not lock other actions performed concurrently. For instance, the user interface remains operational while the data source is populated.
Call the FillAsync method with the await operator.
The cancellationToken parameter provides a way to send the cancellation signal to the task. The task monitors the token and stops when it receives the signal. Create a CancellationTokenSource class instance and pass its Token property to the FillAsync method call. Call the CancellationTokenSource.Cancel method to stop the task.
Example
The code sample below creates an ExcelDataSource and populates it with data in an asynchronous manner. A CancellationTokenSource class instance is used to allow users to interrupt the data source fill process if it takes too long.
using System.Threading;
using System.Threading.Tasks;
using System.IO;
using DevExpress.Utils;
using DevExpress.DataAccess.Excel;
// ...
// Use the cancellationTokenSource to allow users to stop populating the data source.
CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
// ...
// The cancelButton_Click event handler uses the cancellationTokenSource to stop populating the data source.
private void cancelButton_Click(object sender, EventArgs e) {
cancellationTokenSource.Cancel();
}
// ...
// Create and configure an Excel data source.
ExcelDataSource excelDataSource = new ExcelDataSource();
excelDataSource.Name = "Excel Data Source";
excelDataSource.FileName = Path.Combine(Path.GetDirectoryName(typeof(ReportCreator).Assembly.Location), "Sales.xlsx");
ExcelWorksheetSettings worksheetSettings = new ExcelWorksheetSettings("SalesPerson", "A1:L2000");
excelDataSource.SourceOptions = new ExcelSourceOptions(worksheetSettings);
// Populate the data source.
await excelDataSource.FillAsync(cancellationTokenSource.Token);