SqlDataSource.FillAsync(IEnumerable<IParameter>, String[], CancellationToken) Method

Populates the SqlDataSource in an asynchronous manner, passes external parameters to the data source, and uses the cancellationToken parameter to send the cancellation signal. You can specify which queries to execute in order to populate the data source.

Namespace: DevExpress.DataAccess.Sql

Assembly: DevExpress.DataAccess.v23.2.dll

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

Declaration

C#

public Task FillAsync(
    IEnumerable<IParameter> sourceParameters,
    string[] queriesToFill,
    CancellationToken cancellationToken
)

VB.NET

Public Function FillAsync(
    sourceParameters As IEnumerable(Of IParameter),
    queriesToFill As String(),
    cancellationToken As CancellationToken
) As Task

Parameters

Name	Type	Description
sourceParameters	IEnumerable<IParameter>	External parameters passed to the data source.
queriesToFill	String[]	Queries to execute in order to populate the data source.
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 SQL 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 sourceParameters parameter passes a collection of external parameters to the data source. For instance, you can pass report parameters from a reporting application and use report parameter values to filter data.

The queriesToFill array specifies the names of the queries to execute in order to populate the data source.

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.

All queries listed in the queriesToFill parameter are validated one by one. If any validation errors occur, an AggregateException is thrown with these errors. Use the exception’s InnerExceptions property to access a collection of QueryExecutionException objects (use their InnerException property to access an actual ValidationException).

If the validation succeeds, all listed queries are executed one by one. If any errors occur, an AggregateException is thrown with these errors. Use the exception’s InnerExceptions property to access a collection of QueryExecutionException objects (use their InnerException property to access an actual DevExpress.DataAccess.Native.Sql.SqlExecutionException).

Example

The code sample below creates an SqlDataSource, binds the data source query’s catID parameter to the p_catID report parameter, and populates the queryCategories data member 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.ConnectionParameters;
using DevExpress.DataAccess.Sql;
using DevExpress.XtraReports.Parameters;
using DevExpress.XtraReports.UI;
using System.Drawing;
// ...
SqlDataSource DataSource { get; set; }
// ...
public XtraReport CreateReportWithParameter()
{
    XtraReport report = new XtraReport()
    {
        Bands = {
            new DetailBand() {
                Name = "detailBand",
                Controls = {
                    new XRLabel() {
                        Name = "CategoryID",
                        BoundsF = new RectangleF(0,0,100,25),
                        ExpressionBindings = {
                            new ExpressionBinding("BeforePrint", "Text", "[CategoryID]")
                        }
                    },
                    new XRLabel() {
                        Name = "CategoryName",
                        BoundsF = new RectangleF(100,0,200,25),
                        ExpressionBindings = {
                            new ExpressionBinding("BeforePrint", "Text", "[CategoryName]")
                        }
                    }
                }
            }
        },
    };
    report.Parameters.Add(new Parameter()
    {
        Name = "p_catID",
        Type = typeof(int),
        Value = 3
    });
    return report;
}
// ...
public void CreateSqlDataSourceWithParameter()
{
    MsSqlConnectionParameters connectionParameters = new MsSqlConnectionParameters(
        ".", "NorthWind", null, null, MsSqlAuthorizationType.Windows);
    var sqlDataSource = new SqlDataSource(connectionParameters) { Name = "Sql_Categories" };
    var categoriesQuery = SelectQueryFluentBuilder
        .AddTable("Categories")
        .SelectAllColumnsFromTable()
        .Build("Categories");
    categoriesQuery.Name = "queryCategories";
    QueryParameterInitialization(categoriesQuery);
    sqlDataSource.Queries.Add(categoriesQuery);
    sqlDataSource.RebuildResultSchema();
    DataSource = sqlDataSource;
}
// ...
void QueryParameterInitialization(SelectQuery query)
{
    QueryParameter parameter = new QueryParameter()
    {
        Name = "catID",
        Type = typeof(DevExpress.DataAccess.Expression),
        Value = new DevExpress.DataAccess.Expression("?p_catID", typeof(System.Int32))
    };
    query.Parameters.Add(parameter);
    query.FilterString = "CategoryID = ?catID";
}
// ...
void AssignDataSourceToReport()
{
    XtraReport report = CreateReportWithParameter();
    report.DataSource = DataSource;
    report.DataMember = "queryCategories";
}
// ...
// Use the cancellationTokenSource to allow users to stop the task.
System.Threading.CancellationTokenSource cancellationTokenSource =
    new System.Threading.CancellationTokenSource();
// ...
// A user can click the button to stop the task.
private void cancelButton_Click(object sender, System.EventArgs e)
{
    cancellationTokenSource.Cancel();
}
// ...
async void FillDataSourcAsyncQueriesWithParametersCancellable(XtraReport report)
{
    await DataSource.FillAsync(report.Parameters, 
        new string[] { "queryCategories" }, 
        cancellationTokenSource.Token);
}

VB.NET

Imports DevExpress.DataAccess.ConnectionParameters
Imports DevExpress.DataAccess.Sql
Imports DevExpress.XtraReports.Parameters
Imports DevExpress.XtraReports.UI
' ...
Private Property DataSource() As SqlDataSource
' ...
Public Function CreateReportWithParameter() As XtraReport
    Dim report = New XtraReport()
    Dim band = New DetailBand()
    Dim bindings1 = New ExpressionBinding("BeforePrint", "Text", "[CategoryID]")
    Dim bindings2 = New ExpressionBinding("BeforePrint", "Text", "[CategoryName]")
    Dim control1 = New XRLabel() With {
        .Name = "CustomerID",
        .BoundsF = New RectangleF(0, 0, 100, 25)
                    }
    Dim control2 = New XRLabel() With {
        .Name = "CompanyName",
        .BoundsF = New RectangleF(100, 0, 200, 25)
        }

    band.Controls.AddRange(New XRControl() {control1, control2})
    report.Bands.Add(band)
    report.Parameters.Add(New Parameter() With {
                          .Name = "p_catID",
                          .Type = GetType(Integer),
                          .Value = 3})
    Return report
End Function
' ...
Public Sub CreateSqlDataSourceWithParameter()
    Dim connectionParameters As New MsSqlConnectionParameters(
        ".", "NorthWind", Nothing, Nothing, MsSqlAuthorizationType.Windows)
    Dim sqlDataSource = New SqlDataSource(connectionParameters) With {.Name = "Sql_Categories"}
    Dim categoriesQuery = SelectQueryFluentBuilder.
        AddTable("Categories").
        SelectAllColumnsFromTable().
        Build("Categories")
    categoriesQuery.Name = "queryCategories"
    QueryParameterInitialization(categoriesQuery)
    sqlDataSource.Queries.Add(categoriesQuery)
    sqlDataSource.RebuildResultSchema()
    DataSource = sqlDataSource
End Sub
' ...
Private Sub QueryParameterInitialization(ByVal query As SelectQuery)
    Dim parameter As New QueryParameter() With {
        .Name = "catID",
        .Type = GetType(DevExpress.DataAccess.Expression),
        .Value = New DevExpress.DataAccess.Expression("?p_catID", GetType(System.Int32))}
    query.Parameters.Add(parameter)
    query.FilterString = "CategoryID = ?catID"
End Sub
' ...
Private Sub AssignDataSourceToReport()
    Dim report As XtraReport = CreateReportWithParameter()
    report.DataSource = DataSource
    report.DataMember = "queryCategories"
End Sub
' ...
' Use the cancellationTokenSource to allow users to stop the task.
Private cancellationTokenSource As New System.Threading.CancellationTokenSource()
' ...
' A user can click the button to stop the task.
Private Sub cancelButton_Click(ByVal sender As Object, ByVal e As System.EventArgs)
    cancellationTokenSource.Cancel()
End Sub
' ...
Private Async Sub FillDataSourcAsyncQueriesWithParametersCancellable(report As XtraReport)
    Await DataSource.FillAsync(report.Parameters,
                               New String() {"queryCategories"},
                               cancellationTokenSource.Token)
End Sub