DefaultIfEmpty(TSource) Method (IObservable(TSource))

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

Returns the elements of the specified sequence or the type parameter's default value in a singleton sequence if the sequence is empty.

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

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

returnValue = source.DefaultIfEmpty()

Type Parameters


The type of source.


Type: System.IObservable(Of TSource)
The sequence to return a default value for if it is empty.

Return Value

Type: System.IObservable(Of TSource)
An observable sequence that contains the default value for the TSource type if the source is empty; otherwise, the elements of the source itself.

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 or
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