XtraReportBase.DataSourceDemanded Event

Occurs before report generation, to specify a data source for the report.

Namespace: DevExpress.XtraReports.UI

Assembly: DevExpress.XtraReports.v19.1.dll

NuGet Packages: DevExpress.Reporting.Core, DevExpress.WindowsDesktop.Core

Declaration

C#

public event EventHandler<EventArgs> DataSourceDemanded

VB.NET

Public Event DataSourceDemanded As EventHandler(Of EventArgs)

Event Data

The DataSourceDemanded event's data class is EventArgs.

Remarks

In a handler of this event, you can set or modify a value of the report’s XtraReportBase.DataSource property.

You can handle the DataSourceDemanded event to silently pass parameters to a report and populate the report’s data source using a stored procedure.

When this event is raised, all report parameters have already been initialized or assigned values in a Print Preview. You can handle this event to obtain their values.

Example

This example illustrates a workaround enabling you to use multi-value parameters in a query string.

At present, query parameters cannot be directly mapped to multi-value report parameters, and this task is solved by adding a WHERE clause to the SQL string in the following way.

SQL

SELECT [Categories].[CategoryID], [Categories].[CategoryName] FROM [Categories] [Categories]
 WHERE [Categories].[CategoryID] IN (1,2,3)

XtraReport1.vb

Imports DevExpress.DataAccess.Sql
Imports System
Imports System.Collections
Imports System.Text
' ...

Namespace WindowsFormsApplication3
    Partial Public Class XtraReport1
        Inherits DevExpress.XtraReports.UI.XtraReport

        Public Sub New()
            InitializeComponent()

            ' Assign a set of values to the report parameter.
            Me.parameter1.Value = New Integer() { 1, 2, 3 }

            ' Handle the DataSourceDemanded event of a report.
            AddHandler Me.DataSourceDemanded, AddressOf XtraReport1_DataSourceDemanded
        End Sub

        Private Sub XtraReport1_DataSourceDemanded(ByVal sender As Object, ByVal e As EventArgs)
            Dim query As CustomSqlQuery = TryCast(Me.sqlDataSource1.Queries(0), CustomSqlQuery)
            Dim count As Integer = (TryCast(Me.parameter1.Value, IList)).Count
            If count = 0 Then
                Return
            End If
            Dim builder As New StringBuilder()
            builder.Append("("c)
            For i As Integer = 0 To count - 1
                'builder.Append('\''); // Uncomment this line when parsing a string parameter value.
                builder.Append((TryCast(Me.parameter1.Value, IList))(i))
                'builder.Append('\''); // Uncomment this line when parsing a string parameter value.
                If i <> count - 1 Then
                    builder.Append(","c)
                End If
            Next i

            builder.Append(")"c)
            query.Sql &= " WHERE [Categories].[CategoryID] IN " & builder.ToString()
            sqlDataSource1.RebuildResultSchema()
        End Sub
    End Class
End Namespace

XtraReport1.cs

using DevExpress.DataAccess.Sql;
using System;
using System.Collections;
using System.Text;
// ...

namespace WindowsFormsApplication3 {
    public partial class XtraReport1 : DevExpress.XtraReports.UI.XtraReport {
        public XtraReport1() {
            InitializeComponent();

            // Assign a set of values to the report parameter.
            this.parameter1.Value = new int[] { 1, 2, 3 };

            // Handle the DataSourceDemanded event of a report.
            this.DataSourceDemanded += XtraReport1_DataSourceDemanded;
        }

        void XtraReport1_DataSourceDemanded(object sender, EventArgs e) {
            CustomSqlQuery query = this.sqlDataSource1.Queries[0] as CustomSqlQuery;
            int count = (this.parameter1.Value as IList).Count;
            if (count == 0)
                return;
            StringBuilder builder = new StringBuilder();
            builder.Append('(');
            for (int i = 0; i < count; i++) {
                //builder.Append('\''); // Uncomment this line when parsing a string parameter value.
                builder.Append((this.parameter1.Value as IList)[i]);
                //builder.Append('\''); // Uncomment this line when parsing a string parameter value.
                if (i != count - 1)
                    builder.Append(',');
            }

            builder.Append(')');
            query.Sql += " WHERE [Categories].[CategoryID] IN " + builder.ToString();
            sqlDataSource1.RebuildResultSchema();
        }
    }
}

To dynamically update the query string using the values assigned to a report parameter (whose Parameter.MultiValue property is set to true), use the following code in the XtraReportBase.DataSourceDemanded event handler.

XtraReport1.vb

Imports DevExpress.DataAccess.Sql
Imports System
Imports System.Collections
Imports System.Text
' ...

Namespace WindowsFormsApplication3
    Partial Public Class XtraReport1
        Inherits DevExpress.XtraReports.UI.XtraReport

        Public Sub New()
            InitializeComponent()

            ' Assign a set of values to the report parameter.
            Me.parameter1.Value = New Integer() { 1, 2, 3 }

            ' Handle the DataSourceDemanded event of a report.
            AddHandler Me.DataSourceDemanded, AddressOf XtraReport1_DataSourceDemanded
        End Sub

        Private Sub XtraReport1_DataSourceDemanded(ByVal sender As Object, ByVal e As EventArgs)
            Dim query As CustomSqlQuery = TryCast(Me.sqlDataSource1.Queries(0), CustomSqlQuery)
            Dim count As Integer = (TryCast(Me.parameter1.Value, IList)).Count
            If count = 0 Then
                Return
            End If
            Dim builder As New StringBuilder()
            builder.Append("("c)
            For i As Integer = 0 To count - 1
                'builder.Append('\''); // Uncomment this line when parsing a string parameter value.
                builder.Append((TryCast(Me.parameter1.Value, IList))(i))
                'builder.Append('\''); // Uncomment this line when parsing a string parameter value.
                If i <> count - 1 Then
                    builder.Append(","c)
                End If
            Next i

            builder.Append(")"c)
            query.Sql &= " WHERE [Categories].[CategoryID] IN " & builder.ToString()
            sqlDataSource1.RebuildResultSchema()
        End Sub
    End Class
End Namespace

XtraReport1.cs

using DevExpress.DataAccess.Sql;
using System;
using System.Collections;
using System.Text;
// ...

namespace WindowsFormsApplication3 {
    public partial class XtraReport1 : DevExpress.XtraReports.UI.XtraReport {
        public XtraReport1() {
            InitializeComponent();

            // Assign a set of values to the report parameter.
            this.parameter1.Value = new int[] { 1, 2, 3 };

            // Handle the DataSourceDemanded event of a report.
            this.DataSourceDemanded += XtraReport1_DataSourceDemanded;
        }

        void XtraReport1_DataSourceDemanded(object sender, EventArgs e) {
            CustomSqlQuery query = this.sqlDataSource1.Queries[0] as CustomSqlQuery;
            int count = (this.parameter1.Value as IList).Count;
            if (count == 0)
                return;
            StringBuilder builder = new StringBuilder();
            builder.Append('(');
            for (int i = 0; i < count; i++) {
                //builder.Append('\''); // Uncomment this line when parsing a string parameter value.
                builder.Append((this.parameter1.Value as IList)[i]);
                //builder.Append('\''); // Uncomment this line when parsing a string parameter value.
                if (i != count - 1)
                    builder.Append(',');
            }

            builder.Append(')');
            query.Sql += " WHERE [Categories].[CategoryID] IN " + builder.ToString();
            sqlDataSource1.RebuildResultSchema();
        }
    }
}

Related GitHub Examples

The following code snippets (auto-collected from DevExpress Examples) contain references to the DataSourceDemanded event.

Note

The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.

C#

Reporting_how-to-bind-a-web-report-to-a-collection-of-custom-objects-at-design-time-e1936/CS/ShowReport/Default.aspx.cs#L24

XtraReport1 report = new XtraReport1();
report.DataSourceDemanded += report_DataSourceDemanded;
return report;

Reporting_mvc-how-to-pass-parameters-to-a-report-by-using-combobox-control-e20060/CS/DevExpressMvcApplication1/Controllers/HomeController.cs#L41

report.DataSourceDemanded += (s, e) => {
    ((XtraReport)s).DataSource = new NorthwindEntities().Products;

Reporting_how-to-pass-a-multi-value-parameter-to-a-query-t352379/CS/WindowsFormsApplication3/XtraReport1.cs#L16

    // Handle the DataSourceDemanded event of a report.
    this.DataSourceDemanded += XtraReport1_DataSourceDemanded;
}

VB.NET

Reporting_how-to-bind-a-web-report-to-a-collection-of-custom-objects-at-design-time-e1936/VB/ShowReport/Default.aspx.vb#L26

Dim report As New XtraReport1()
AddHandler report.DataSourceDemanded, AddressOf report_DataSourceDemanded
Return report

Reporting_mvc-how-to-pass-parameters-to-a-report-by-using-combobox-control-e20060/VB/DevExpressMvcApplication1/Controllers/HomeController.vb#L45

AddHandler report.DataSourceDemanded, AddressOf DataSourceDemandedEventHandler
Return report

Reporting_how-to-pass-a-multi-value-parameter-to-a-query-t352379/VB/WindowsFormsApplication3/XtraReport1.vb#L18

    ' Handle the DataSourceDemanded event of a report.
    AddHandler Me.DataSourceDemanded, AddressOf XtraReport1_DataSourceDemanded
End Sub