Observable.SingleOrDefault(Of TSource) Method (IObservable(Of TSource))

Returns the only element of an observable sequence, or a default value if the observable sequence is empty.

Namespace:  System.Reactive.Linq
Assembly:  System.Reactive (in System.Reactive.dll)

<ExtensionAttribute> _
Public Shared Function SingleOrDefault(Of TSource) ( _
	source As IObservable(Of TSource) _
) As TSource
Dim source As IObservable(Of TSource)
Dim returnValue As TSource

returnValue = source.SingleOrDefault()

Type Parameters


The type of source.


Type: System.IObservable(Of TSource)
The source observable sequence.

Return Value

Type: TSource
The single element in the observable sequence, or a default value if no value is found.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IObservable(Of TSource). When you use instance method syntax to call this method, omit the first parameter. For more information, see https://msdn.microsoft.com/en-us/library/bb384936.aspx or https://msdn.microsoft.com/en-us/library/bb383977.aspx.