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AllowNull Property
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FarPoint.Win Assembly > FarPoint.Win Namespace > SuperEditBase Class : AllowNull Property


Glossary Item Box

Gets or sets whether the control considers a null value valid.

Syntax

Visual Basic (Declaration) 
Public Overridable Property AllowNull As Boolean
Visual Basic (Usage)Copy Code
Dim instance As SuperEditBase
Dim value As Boolean
 
instance.AllowNull = value
 
value = instance.AllowNull
C# 
public virtual bool AllowNull {get; set;}

Property Value

Boolean value: true to allow null as user input; false otherwise

Remarks

When this property is set to true, the edit control accepts null values, and the user can provide a null value in the following ways:

  • Press F2.
  • Delete the contents of the edit control.
  • Call the SetNull method.
  • Call the ClearAll method.
  • Select the contents of the control and call the Clear method.

This property is available from the SuperEditBase class.

This property must be set to true for the NullColor property to work correctly.

You can return whether a control contains the null value by calling the IsNull method.

Example

C#Copy Code
private void Form1_Load(object sender, System.EventArgs e)
{
   control.NullColor = Color.Coral;
   control.AllowNull = true;
   control.CausesValidation = true;
   control.Text = "";
}

private void button1_Click(object sender, System.EventArgs e)
{
   control.ResetNullColor();
}
Visual BasicCopy Code
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
   control.NullColor = Color.Coral
   control.AllowNull = True
   control.CausesValidation = True
   control.Text = ""
End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
   control.ResetNullColor()
End Sub

Requirements

Target Platforms: Windows 2000 Professional (SP4), Windows 2000 Server, Windows 2003 Server (SP1), Windows 2008, Windows XP (SP2), Windows Vista, Windows 7, Windows 8

See Also

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