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

• Apr 08, 2019
• 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.

Note

A complete sample project is available at https://github.com/DevExpress-Examples/how-to-validate-objectdatasource-in-the-spreadsheet-mail-merge-template-t515368

MyObjectDataSourceValidationService.vb

Public Class MyObjectDataSourceValidationService
    Implements IObjectDataSourceValidationService

    Public Sub Validate(ByVal dataSources As IEnumerable(Of ObjectDataSource)) Implements IObjectDataSourceValidationService.Validate
        ' Do nothing to allow loading.
        ' Clear the DataSource and DataMember properties to prohibit 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.vb

<STAThread> _
Shared Sub Main()
    Dim workbook As Workbook = New DevExpress.Spreadsheet.Workbook()
    workbook.ReplaceService(Of IObjectDataSourceValidationService)(New MyObjectDataSourceValidationService())
    workbook.LoadDocument("EmployeesMailMergeTemplate.xlsx")
    Dim result = workbook.GenerateMailMergeDocuments()
    result(0).SaveDocument("result.xlsx")
    System.Diagnostics.Process.Start("result.xlsx")
End Sub

Program.cs

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

MyObjectDataSourceValidationService.cs

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