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

Qbservable.SingleOrDefaultAsync(IQbservable) method¶

Defined in

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

Applies to

netstandard2.0

Overloads¶

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

1. Overload¶

public static IQbservable<TSource?> SingleOrDefaultAsync<TSource>(this IQbservable<TSource> source)

Summary: Returns the only element of an observable sequence, or a default value if the observable sequence is empty; this method reports an exception if there is more than 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, or a default value if no such element exists.

Exceptions

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

2. Overload¶

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

Summary: Returns the only element of an observable sequence that matches the predicate, or a default value if no such element exists; this method reports an exception if there is more than 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, or a default value if no such element exists.

Exceptions

Type	Condition
System.ArgumentNullException	`source` or `predicate` is null.
System.InvalidOperationException	(Asynchronous) The sequence contains more than one element that satisfies the condition in the predicate.