wpf-devexpress-dot-xpf-dot-core-dot-datasources-dot-unbounddatasource-6229f796.md
Occurs before a value is pulled from the data source.
Namespace : DevExpress.Xpf.Core.DataSources
Assembly : DevExpress.Xpf.Core.v25.2.dll
NuGet Package : DevExpress.Wpf.Core
public event EventHandler<UnboundSourceValueNeededEventArgs> ValueNeeded
Public Event ValueNeeded As EventHandler(Of UnboundSourceValueNeededEventArgs)
The ValueNeeded event's data class is UnboundSourceValueNeededEventArgs. The following properties provide information specific to this event:
| Property | Description |
|---|---|
| PropertyIndex | |
| PropertyName | Gets the name of the property whose value is requested. |
| RowIndex | Gets the row index of the value. |
| Tag | Gets an object that contains data associated with the value. |
| Value | Specifies the value which is requested. |
The event data class exposes the following methods:
| Method |
|---|
| SetValue<T>(T) |
Handle the ValueNeeded event to pull a value from the data source.
The following code snippet (auto-collected from DevExpress Examples) contains a reference to the ValueNeeded event.
Note
The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.
use-unbounddatasource-to-populate-wpf-data-grid-with-data/CS/UnboundSource/MainWindow.xaml#L20
Count="5"
ValueNeeded="UnboundDataSource_ValueNeeded"
ValuePushed="UnboundDataSource_ValuePushed">
#line 20 "..\..\..\MainWindow.xaml"
this.unboundDataSource1.ValueNeeded += new System.EventHandler<DevExpress.Data.UnboundSourceValueNeededEventArgs>(this.UnboundDataSource_ValueNeeded);
#ExternalSource("..\..\MainWindow.xaml",20)
AddHandler Me.unboundDataSource1.ValueNeeded, New System.EventHandler(Of DevExpress.Data.UnboundSourceValueNeededEventArgs)(AddressOf Me.UnboundDataSource_ValueNeeded)
See Also