How to: Validate Data When a New Row is Added to a ListObject Control

Applies to
The information in this topic applies only to the specified Visual Studio Tools for Office projects and versions of Microsoft Office. Document-level projects Excel 2007 Excel 2003 Application-level projects Excel 2007 For more information, see Features Available by Application and Project Type.

Users can add new rows to a ListObject control that is bound to data. You can validate the user's data before committing the changes to the data source.

If an error occurs, you can write code to provide additional data to correct the error. For more information, see How to: Handle Errors When a New Row is Added to a ListObject Control.

Data Validation

Whenever a row is added to a ListObject that is bound to data, the BeforeAddDataBoundRow event is raised. You can handle this event to perform your data validation. For example, if your application requires that only employees between the ages of 18 and 65 can be added to the data source, you can verify that the age entered falls within that range before the row is added.

Note

You should always check user input on the server in addition to the client. For more information, see Secure Client Applications (ADO.NET).

To validate data when a new row is added to data-bound ListObject

1. Create variables for the ID and DataTable at the class level.

   Dim id As Integer = 0
   Dim employeeTable As System.Data.DataTable
   

   private int id = 0;
   private System.Data.DataTable employeeTable;
   

2. Create a new DataTable and add sample columns and data in the Startup event handler of the Sheet1 class (in a document-level project) or ThisAddIn class (in an application-level project).

   employeeTable = New System.Data.DataTable("Employees")
   
   Dim column As System.Data.DataColumn = _
       employeeTable.Columns.Add("Id", GetType(Int32))
   column.AllowDBNull = False
   
   employeeTable.Columns.Add("FirstName", GetType(String))
   employeeTable.Columns.Add("LastName", GetType(String))
   employeeTable.Columns.Add("Age", GetType(Int32))
   
   employeeTable.Rows.Add(id, "Nancy", "Anderson", 56)
   employeeTable.Rows.Add(id, "Robert", "Brown", 44)
   id += 1
   
   list1.SetDataBinding(employeeTable, "", "FirstName", "LastName", "Age")
   

   employeeTable = new System.Data.DataTable("Employees");
   
   System.Data.DataColumn column = employeeTable.Columns.Add
       ("Id", typeof(int));
   column.AllowDBNull = false;
   
   employeeTable.Columns.Add("FirstName", typeof(string));
   employeeTable.Columns.Add("LastName", typeof(string));
   employeeTable.Columns.Add("Age", typeof(int));
   
   employeeTable.Rows.Add(id, "Nancy", "Anderson", "56");
   employeeTable.Rows.Add(id, "Robert", "Brown", "44");
   id++;
   
   list1.SetDataBinding(employeeTable, "", "FirstName", "LastName", "Age");
   
   list1.BeforeAddDataBoundRow +=new Microsoft.Office.Tools.Excel.
       BeforeAddDataBoundRowEventHandler(list1_BeforeAddDataBoundRow);
   

3. Add code to the list1_BeforeAddDataBoundRow event handler to check whether the age entered falls within the acceptable range.

   Private Sub list1_BeforeAddDataBoundRow(ByVal sender As Object, ByVal e As  _
       Microsoft.Office.Tools.Excel.BeforeAddDataBoundRowEventArgs) _
       Handles list1.BeforeAddDataBoundRow
   
       Dim row As System.Data.DataRow = (CType(e.Item, System.Data.DataRowView)).Row
   
       If Not row("Age") Is Nothing And Not row("Age") Is Convert.DBNull Then 
   
           Dim ageEntered As Integer = CType(row("Age"), Int32)
   
           If ageEntered < 21 Or ageEntered > 65 Then
               System.Windows.Forms.MessageBox.Show _
                   ("Age must be between 21 and 65. The row cannot be added.")
               e.Cancel = True 
               Return 
           End If
   
           row("ID") = id
           id += 1
   
       Else
           System.Windows.Forms.MessageBox.Show("You must enter an age.")
           e.Cancel = True 
       End If 
   End Sub
   

   private void list1_BeforeAddDataBoundRow(object sender,
       Microsoft.Office.Tools.Excel.BeforeAddDataBoundRowEventArgs e)
   {
       System.Data.DataRow row = ((System.Data.DataRowView)e.Item).Row;
   
       if (row["Age"] != null && row["Age"] != Convert.DBNull)
       {
           int ageEntered = (int)row["Age"];
   
           if (ageEntered < 21 || ageEntered > 65)
           {
               System.Windows.Forms.MessageBox.Show
                   ("Age must be between 21 and 65. The row cannot be added.");
               e.Cancel = true;
               return;
           }
           row["ID"] = id;
           id++;
       }
       else
       {
           System.Windows.Forms.MessageBox.Show("You must enter an age.");
           e.Cancel = true;
       }
   }
   

Compiling the Code

This code example assumes that you have an existing ListObject named list1 on the worksheet in which this code appears.

See Also

Tasks

How to: Map ListObject Columns to Data

How to: Handle Errors When a New Row is Added to a ListObject Control

Concepts

Extending Word Documents and Excel Workbooks in Application-Level Add-ins at Run Time

Excel Application-Level Add-in Development

Adding Controls to Office Documents at Run Time

ListObject Control

Understanding ListObject Column and Row Order Persistence

Other Resources

Controls on Office Documents

Excel Host Controls

Change History

Date	History	Reason
July 2008	Modified the example so that it can be used in an application-level add-in.	SP1 feature change.