corelibraries-devexpress-dot-data-dot-unboundsource-ebbfa9a8.md
Occurs when a value is requested from the UnboundSource.
Namespace : DevExpress.Data
Assembly : DevExpress.Data.v25.2.dll
NuGet Package : DevExpress.Data
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 this event to obtain data from your data source. An example is provided in the UnboundSource topic.
The following code snippets (auto-collected from DevExpress Examples) contain references 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.
XDL_how-to-utilize-the-unboundsource-component-in-code-t474976/CS/UnboundDS-Code/Form1.cs#L25
unboundSourceProperty2});
unboundDS.ValueNeeded += unboundDS_ValueNeeded;
unboundDS.ValuePushed += unboundDS_ValuePushed;
wpf-data-grid-use-unbounddatasource-with-source-generator/CS/ViewModels/MainViewModel.cs#L30
//Processes the data pull operation
UnboundSource.ValueNeeded += (_, e) => {
if (EqualityComparer<string>.Default.Equals(e.PropertyName, nameof(Item.Id)))
XDL_how-to-utilize-the-unboundsource-component-in-code-t474976/VB/UnboundDS-Code/Form1.vb#L25
unboundDS.Properties.AddRange(New DevExpress.Data.UnboundSourceProperty() { unboundSourceProperty1, unboundSourceProperty2})
AddHandler unboundDS.ValueNeeded, AddressOf unboundDS_ValueNeeded
AddHandler unboundDS.ValuePushed, AddressOf unboundDS_ValuePushed
See Also