How to add Column/Row Validation Using Typed DataTable

In this post we will see how we can add the Validation Rule in Typed DataTable of a Typed DataSet (using Partial Class) and then how can we use this Validation on our Form in DataGridView or Details.

Level: Intermediate

Knowledge Required:

• Typed DataSet
• DataTable
• Partial Class
• DataGridView
• ErrorProvider

Description:
This post is based on Beth Massi's Video Tutorial.

As we have used the DataGridView control for entering the data in a DataTable. If we have set one column of our DataTable AllowDBNull = False, then in DataGridView we encounter an exception when we try to enter a Null in this column. This exception can be handled in DataError event of DataGridView control. But the row will be removed from list anyway. So to make it more user friendly, we do the following things,

1) Set the AllowDBNull = True for the column
2) Add Validation Rule in the DataTable

Example:
I have created a Typed DataSet StudentDataSet in which I have added 1 Table

• Student_ID (primary key, AllowDBNull=False, AutoIncreament=True)
• Student_Name (AllowDBNull=True)
• Father_Name (AllowDBNull=True)
• Age (AllowDBNull=True)

All the columns (except the 1st one) are Allowed to have NULL values. Now we will add the Validation Business Rule in our DataTable by using Partial Class as,

Partial Class StudentDataSet
    Partial Class StudentDataTable
        Private Sub CheckStudentName(ByVal rowStudent As StudentDataSet.StudentRow)
            If rowStudent.IsStudent_NameNull() OrElse rowStudent.Student_Name = "" Then
                ' set error
                rowStudent.SetColumnError(Me.Student_NameColumn, "Student Name is Required")
            Else
                ' ok clear the error
                rowStudent.SetColumnError(Me.Student_NameColumn, "")
            End If
        End Sub

        Private Sub CheckAge(ByVal rowStudent As StudentDataSet.StudentRow)
            If rowStudent.IsAgeNull OrElse _
                rowStudent.Age < 3 OrElse _
                rowStudent.Age > 10 Then
                rowStudent.SetColumnError(Me.AgeColumn, "Age must be between 3 to 10")
            Else
                rowStudent.SetColumnError(Me.AgeColumn, "")
            End If
        End Sub

        Private Sub StudentDataTable_ColumnChanged(ByVal sender As Object, ByVal e As System.Data.DataColumnChangeEventArgs) Handles Me.ColumnChanged
            If e.Column Is Me.Student_NameColumn Then
                Call Me.CheckStudentName(CType(e.Row, StudentRow))
            ElseIf e.Column Is Me.AgeColumn Then
                Call Me.CheckAge(CType(e.Row, StudentRow))
            End If
        End Sub

        Private Sub StudentDataTable_TableNewRow(ByVal sender As Object, ByVal e As System.Data.DataTableNewRowEventArgs) Handles Me.TableNewRow
            Call Me.CheckStudentName(CType(e.Row, StudentRow))
            Call Me.CheckAge(CType(e.Row, StudentRow))
        End Sub
    End Class
End Class

First we have created 2 private methods

1) CheckStudentName() - validates the Student Name column
2) CheckAge() - validates the Age column

Then we have used 2 DataTable Events

1) ColumnChanged - in this event handler we check which column has been changed then we call the method according to that column
2) TableNewRow - in this event handler we execute both methods, since whole row is chagned

Here we have done with our Custom Validation. Now we just simply put the DataGridView control on Form, bind it with this DataTable and the rest of the things will be handled by DataGridView itself.

DataGridView:

As you can see the DataGridView is Displaying a Red Icon in the Age column and it displays a ToolTip of Error that we have set in our Validation.

And finally when we are about to Save this Table, then we will first check the Error as,

If Me.StudentDataSet.Student.HasErrors() Then
    MsgBox("Table contains Error, cannot save", MsgBoxStyle.Exclamation, "Save")
Else
    MsgBox("Table does NOT contain any Error, can Save now", MsgBoxStyle.Information, "Save")
End If

Detail View:


Now we can implement the same thing in our Detail View. As you can see the above Form I have put the TextBox Controls and have Bind them with the same Table. But to show the Error Icon we will use the ErrorProvider Component.

1) Add the ErrorProvider Component
2) Set its BindingSource to the StudentBindingSource

That is it, ErrorProvider will display the Error Icon with TextBox that violates the Business Rule. Note that StudentBindingSource is the same BindingSource which is Bound with the TextBox Controls.

Project Details:
Custom Validation on Typed DataTable

Project Download:
CustomValidation.zip