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.v23.2.dll

NuGet Packages: DevExpress.DataAccess, DevExpress.Win.PivotGrid, DevExpress.Win.TreeMap

Declaration

C#

public Task FillAsync(
    CancellationToken cancellationToken
)

VB.NET

Public Function FillAsync(
    cancellationToken As CancellationToken
) As Task

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.

C#

using DevExpress.DataAccess.Excel;
using DevExpress.XtraReports.UI;
using System.Threading;
// ...
// Creates and configures the Excel data source.
ExcelDataSource excelDataSource = new ExcelDataSource();
excelDataSource.Name = "Excel Data Source";
excelDataSource.FileName = "Sales.xlsx";
ExcelWorksheetSettings worksheetSettings = new ExcelWorksheetSettings("SalesPerson", "A1:L2000");
excelDataSource.SourceOptions = new ExcelSourceOptions(worksheetSettings);
// Populates the data source.
await excelDataSource.FillAsync(cancellationTokenSource.Token);
// The cancellationTokenSource allows the users to stop the task.
CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
// ...
// Click the button to stop the task.
void cancelButton_Click(object sender, System.EventArgs e)
{
    cancellationTokenSource.Cancel();
}

VB.NET

' Creates and configures the Excel data source.
Dim excelDataSource As New ExcelDataSource()
excelDataSource.Name = "Excel Data Source"
excelDataSource.FileName = "Sales.xlsx"
Dim worksheetSettings As New ExcelWorksheetSettings("SalesPerson", "A1:L2000")
excelDataSource.SourceOptions = New ExcelSourceOptions(worksheetSettings)
' Populates the data source.
Await excelDataSource.FillAsync(cancellationTokenSource.Token)
' The cancellationTokenSource allows the users to stop the task.
Dim cancellationTokenSource As New CancellationTokenSource()
' Click the button to stop the task.
Private Sub cancelButton_Click(ByVal sender As Object, ByVal e As System.EventArgs)
    cancellationTokenSource.Cancel()
End Sub