How to: Change the Mail Merge data sources at runtime

Dec 17, 2020
5 minutes to read

This example illustrates how to switch data sources used for Mail Merge in ASPxRichEdit at runtime.

To update ASPxRichEdit’s data source dynamically, wrap it in the ASPxCallbackPanel control and use its callbacks to refresh data.

Note that ASPxRichEdit should be bound to actual data on every round-trip to the server, so it is insufficient to set the data source in the server-side Callback event handler only. It’s necessary to restore the actual data source and bind ASPxRichEdit to it on each request in the Page_Init event handler.

In addition, it is necessary to clear the current document in ASPxRichEdit each time the data source is changed. For this purpose, you can use the server-side New() method.

MergeDataModels.cs
Default.aspx.cs
Default.aspx (C#)
Default.aspx.vb
MergeDataModels.vb
Default.aspx (VB.NET)

csharp

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

public static class MergeDataModels
{
    public static List<TestMergeModel1> GetTestData1() {
        var ds = new List<TestMergeModel1>();
        for (int i = 0; i < 10; i++) {
            ds.Add(new TestMergeModel1 {
                FirstName1 = "First Name_1_" + i,
                LastName1 = "LastName_1_" + i,
                Address1 = "Address_1_" + i
            });
        }
        return ds;
    }
    public static List<TestMergeModel2> GetTestData2() {
        var ds = new List<TestMergeModel2>();
        for (int i = 0; i < 10; i++) {
            ds.Add(new TestMergeModel2 {
                FirstName2 = "First Name_2_" + i,
                LastName2 = "LastName_2_" + i,
                Address2 = "Address_2_" + i
            });
        }
        return ds;
    }    
}

public class TestMergeModel1
{
    public string FirstName1 { get; set; }
    public string LastName1 { get; set; }
    public string Address1 { get; set; }
}

public class TestMergeModel2
{
    public string FirstName2 { get; set; }
    public string LastName2 { get; set; }
    public string Address2 { get; set; }
}

csharp

using DevExpress.Web;
using DevExpress.Web.Office;

public partial class _Default : System.Web.UI.Page {
    protected void Page_Init(object sender, EventArgs e) {
        if (Session["dataMerge"] != null) {
            ASPxRichEdit1.DataSource = Session["dataMerge"];
            ASPxRichEdit1.DataBind();
        }
    }
    protected void ASPxCallbackPanel1_Callback(object sender, CallbackEventArgsBase e) {
        ASPxRichEdit1.New();
        if (Convert.ToInt32(ASPxComboBox1.Value) == 1)
            Session["dataMerge"] = MergeDataModels.GetTestData1();
        else
            Session["dataMerge"] = MergeDataModels.GetTestData2();
        ASPxRichEdit1.DataSource = Session["dataMerge"];
        ASPxRichEdit1.DataBind();
    }

}

aspx

<script>
    function onSelectedIndexChanged(s, e) {
        cp.PerformCallback();
    }
</script>
<dx:ASPxComboBox ID="ASPxComboBox1" runat="server" ClientInstanceName="cb" ValueType="System.Int32" Width="210">
    <Items>
        <dx:ListEditItem Value="1" Text="Data source for Mail Merge #1" />
        <dx:ListEditItem Value="2" Text="Data source for Mail Merge #2" />
    </Items>
    <ClientSideEvents SelectedIndexChanged="onSelectedIndexChanged" />
</dx:ASPxComboBox>


To check that the data source is applied, try to insert mail merge fields and view merged data
<dx:ASPxCallbackPanel ID="ASPxCallbackPanel1" runat="server" ClientInstanceName="cp" OnCallback="ASPxCallbackPanel1_Callback">
    <PanelCollection>
        <dx:PanelContent runat="server" SupportsDisabledAttribute="True">
            <dx:ASPxRichEdit ID="ASPxRichEdit1" runat="server" WorkDirectory="~\App_Data\WorkDirectory">
                <Settings>
                <Behavior CreateNew="Hidden" Save="Hidden" Open="Hidden" SaveAs="Hidden" />
                </Settings>
            </dx:ASPxRichEdit>
        </dx:PanelContent>
    </PanelCollection>
</dx:ASPxCallbackPanel>

Imports DevExpress.Web
Imports DevExpress.Web.Office

Partial Public Class _Default
    Inherits System.Web.UI.Page
    Protected Sub Page_Init(ByVal sender As Object, ByVal e As EventArgs)
        If Session("dataMerge") IsNot Nothing Then
            ASPxRichEdit1.DataSource = Session("dataMerge")
            ASPxRichEdit1.DataBind()
        End If
    End Sub
    Protected Sub ASPxCallbackPanel1_Callback(ByVal sender As Object, ByVal e As CallbackEventArgsBase)
        ASPxRichEdit1.New
        If Convert.ToInt32(ASPxComboBox1.Value) = 1 Then
            Session("dataMerge") = MergeDataModels.GetTestData1()
        Else
            Session("dataMerge") = MergeDataModels.GetTestData2()
        End If
        ASPxRichEdit1.DataSource = Session("dataMerge")
        ASPxRichEdit1.DataBind()
    End Sub

End Class

Public NotInheritable Class MergeDataModels
    Private Sub New()
    End Sub
    Public Shared Function GetTestData1() As List(Of TestMergeModel1)
        Dim ds = New List(Of TestMergeModel1)()
        For i As Integer = 0 To 9
            ds.Add(New TestMergeModel1 With {.FirstName1 = "First Name_1_" & i, .LastName1 = "LastName_1_" & i, .Address1 = "Address_1_" & i})
        Next i
        Return ds
    End Function
    Public Shared Function GetTestData2() As List(Of TestMergeModel2)
        Dim ds = New List(Of TestMergeModel2)()
        For i As Integer = 0 To 9
            ds.Add(New TestMergeModel2 With {.FirstName2 = "First Name_2_" & i, .LastName2 = "LastName_2_" & i, .Address2 = "Address_2_" & i})
        Next i
        Return ds
    End Function
End Class

Public Class TestMergeModel1
    Private privateFirstName1 As String
    Public Property FirstName1() As String
        Get
            Return privateFirstName1
        End Get
        Set(ByVal value As String)
            privateFirstName1 = value
        End Set
    End Property
    Private privateLastName1 As String
    Public Property LastName1() As String
        Get
            Return privateLastName1
        End Get
        Set(ByVal value As String)
            privateLastName1 = value
        End Set
    End Property
    Private privateAddress1 As String
    Public Property Address1() As String
        Get
            Return privateAddress1
        End Get
        Set(ByVal value As String)
            privateAddress1 = value
        End Set
    End Property
End Class

Public Class TestMergeModel2
    Private privateFirstName2 As String
    Public Property FirstName2() As String
        Get
            Return privateFirstName2
        End Get
        Set(ByVal value As String)
            privateFirstName2 = value
        End Set
    End Property
    Private privateLastName2 As String
    Public Property LastName2() As String
        Get
            Return privateLastName2
        End Get
        Set(ByVal value As String)
            privateLastName2 = value
        End Set
    End Property
    Private privateAddress2 As String
    Public Property Address2() As String
        Get
            Return privateAddress2
        End Get
        Set(ByVal value As String)
            privateAddress2 = value
        End Set
    End Property
End Class

aspx

<script>
    function onSelectedIndexChanged(s, e) {
        cp.PerformCallback();
    }
</script>
Choose the required Mail Merge data source:
<dx:ASPxComboBox ID="ASPxComboBox1" runat="server" ClientInstanceName="cb" ValueType="System.Int32" Width="210">
    <Items>
        <dx:ListEditItem Value="1" Text="Data source for Mail Merge #1" />
        <dx:ListEditItem Value="2" Text="Data source for Mail Merge #2" />
    </Items>
    <ClientSideEvents SelectedIndexChanged="onSelectedIndexChanged" />
</dx:ASPxComboBox>


To check that the data source is applied, try to insert mail merge fields and view merged data
<dx:ASPxCallbackPanel ID="ASPxCallbackPanel1" runat="server" ClientInstanceName="cp" OnCallback="ASPxCallbackPanel1_Callback">
    <PanelCollection>
        <dx:PanelContent runat="server" SupportsDisabledAttribute="True">
            <dx:ASPxRichEdit ID="ASPxRichEdit1" runat="server" WorkDirectory="~\App_Data\WorkDirectory">
                <Settings>
                <Behavior CreateNew="Hidden" Save="Hidden" Open="Hidden" SaveAs="Hidden" />
                </Settings>
            </dx:ASPxRichEdit>
        </dx:PanelContent>
    </PanelCollection>
</dx:ASPxCallbackPanel>