How to: Validate the ObjectDataSource Contained in the Spreadsheet MailMerge Template

Sep 25, 2023
2 minutes to read

Loading the mail merge templates with the ObjectDataSource data source may cause undesired behavior if the data source is contained in a compiled assembly. This example illustrates how to use a custom service that implements the IObjectDataSourceValidationService interface to validate an ObjectDataSource contained in the loaded mail merge template and prevent the data source from loading.

MyObjectDataSourceValidationService.cs
MyObjectDataSourceValidationService.vb

csharp

public class MyObjectDataSourceValidationService : IObjectDataSourceValidationService {
    public void Validate(IEnumerable<ObjectDataSource> dataSources)
    {
        // Do nothing to allow the control to load data.
        // Clear the DataSource and DataMember properties to prohibit data loading.
        foreach (ObjectDataSource ds in dataSources)
        {
            if (ds.Name != "EmployeeDS")
            {
                ds.DataSource = null;
                ds.DataMember = null;
            }
        };
    }
}

Public Class MyObjectDataSourceValidationService
    Implements IObjectDataSourceValidationService

    Public Sub Validate(ByVal dataSources As IEnumerable(Of ObjectDataSource)) Implements IObjectDataSourceValidationService.Validate
        ' Do nothing to allow the control to load data.
        ' Clear the DataSource and DataMember properties to prohibit data loading.
        For Each ds As ObjectDataSource In dataSources
            If ds.Name <> "EmployeeDS" Then
                ds.DataSource = Nothing
                ds.DataMember = Nothing
            End If
        Next ds
    End Sub
End Class

Program.cs
Program.vb

csharp

using DevExpress.Spreadsheet;
using System.Diagnostics;
static void Main()
{
    Workbook workbook = new Workbook();
    workbook.ReplaceService<IObjectDataSourceValidationService>(new MyObjectDataSourceValidationService());
    workbook.LoadDocument("EmployeesMailMergeTemplate.xlsx");
    var result = workbook.GenerateMailMergeDocuments();
    result[0].SaveDocument("result.xlsx");
    Process.Start("result.xlsx");
}

Imports DevExpress.Spreadsheet
Imports System.Diagnostics

Shared Sub Main()
    Dim workbook As Workbook = Workbook()
    workbook.ReplaceService(Of IObjectDataSourceValidationService)(New MyObjectDataSourceValidationService())
    workbook.LoadDocument("EmployeesMailMergeTemplate.xlsx")
    Dim result = workbook.GenerateMailMergeDocuments()
    result(0).SaveDocument("result.xlsx")
    Process.Start("result.xlsx")
End Sub