docs-desktop/dotnet-desktop-guide/framework/winforms/controls/how-to-bind-windows-forms-controls-to-dbnull-database-values.md

title, ms.date, dev_langs, helpviewer_keywords, ms.assetid

title	ms.date	dev_langs	helpviewer_keywords	ms.assetid
Bind Controls to DBNull Database Values	03/30/2017	csharp vb	BindingSource component [Windows Forms], binding to DBNull values examples [Windows Forms], BindingSource component controls [Windows Forms], binding to DBNull values	96494e6f-5f40-4f83-af97-bbd7192c2af8

How to: Bind Windows Forms Controls to DBNull Database Values

When you bind Windows Forms controls to a data source and the data source returns a xref:System.DBNull value, you can substitute an appropriate value without handling, formatting, or parsing events. The xref:System.Windows.Forms.Binding.NullValue%2A property will convert xref:System.DBNull to a specified object when formatting or parsing the data source values.

Example

The following example demonstrates how to bind a xref:System.DBNull value in two different situations. The first demonstrates how to set the xref:System.Windows.Forms.Binding.NullValue%2A for a string property; the second demonstrates how to set the xref:System.Windows.Forms.Binding.NullValue%2A for an image property.

[!code-csharpSystem.Windows.Forms.BindingDBNull#1] [!code-vbSystem.Windows.Forms.BindingDBNull#1]

The types of the bound property and the xref:System.Windows.Forms.Binding.NullValue%2A property must be the same or an error will result, and no further xref:System.Windows.Forms.Binding.NullValue%2A values will be processed. In this situation, an exception will not be thrown.

Compiling the Code

This example requires:

• References to the System, System.Data, System.Drawing and System.Windows.Forms assemblies.

See also

• BindingSource Component
• How to: Handle Errors and Exceptions that Occur with Databinding
• How to: Bind a Windows Forms Control to a Type