)} ,System.Linq.Expressions.Expression})}

Qbservable.SingleAsync(IQbservable) method¶

Defined in

Type: Qbservable Namespace: System.Reactive.Linq Assembly: System.Reactive.dll

Applies to

netstandard2.0

Overloads¶

1. public static IQbservable<TSource> SingleAsync<TSource>(this IQbservable<TSource> source)
2. public static IQbservable<TSource> SingleAsync<TSource>(this IQbservable<TSource> source, Expression<Func<TSource, bool>> predicate)

1. Overload¶

public static IQbservable<TSource> SingleAsync<TSource>(this IQbservable<TSource> source)

Summary: Returns the only element of an observable sequence, and reports an exception if there is not exactly one element in the observable sequence.

Type parameters

Name	Description
`TSource`	The type of the elements in the source sequence.

Parameters

Name	Type	Description
`source`	[IQbservable](#	Source observable sequence.

Returns: IQbservable -- Sequence containing the single element in the observable sequence.

Exceptions

Type	Condition
System.ArgumentNullException	`source` is null.
System.InvalidOperationException	(Asynchronous) The source sequence contains more than one element. -or- The source sequence is empty.

2. Overload¶

public static IQbservable<TSource> SingleAsync<TSource>(this IQbservable<TSource> source, Expression<Func<TSource, bool>> predicate)

Summary: Returns the only element of an observable sequence that satisfies the condition in the predicate, and reports an exception if there is not exactly one element in the observable sequence.

Type parameters

Name	Description
`TSource`	The type of the elements in the source sequence.

Parameters

Name	Type	Description
`source`	[IQbservable](#	Source observable sequence.
`predicate`	Expression>	A predicate function to evaluate for elements in the source sequence.

Returns: IQbservable -- Sequence containing the single element in the observable sequence that satisfies the condition in the predicate.

Exceptions

Type	Condition
System.ArgumentNullException	`source` or `predicate` is null.
System.InvalidOperationException	(Asynchronous) No element satisfies the condition in the predicate. -or- More than one element satisfies the condition in the predicate. -or- The source sequence is empty.