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How to: Bind Windows Forms Controls to DBNull Database Values |
03/30/2017 |
.net-framework |
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article |
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96494e6f-5f40-4f83-af97-bbd7192c2af8 |
17 |
dotnet-bot |
dotnetcontent |
wpickett |
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.
For information about building this example from the command line for [!INCLUDEvbprvb] or [!INCLUDEcsprcs], see Building from the Command Line or Command-line Building With csc.exe. You can also build this example in [!INCLUDEvsprvs] by pasting the code into a new project. Also see How to: Compile and Run a Complete Windows Forms Code Example Using Visual Studio.
See Also
BindingSource Component
How to: Handle Errors and Exceptions that Occur with Databinding
How to: Bind a Windows Forms Control to a Type