Syntax
| Visual Basic (Declaration) | |
|---|---|
Public Overridable Property AllowNull As Boolean | |
| Visual Basic (Usage) |  Copy Code |
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Dim instance As SuperEditBase Dim value As Boolean instance.AllowNull = value value = instance.AllowNull | |
| C# | |
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public virtual bool AllowNull {get; set;} | |
Property Value
Boolean value: true to allow null as user input; false otherwiseRemarks
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 Basic | Copy 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 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2