XPQueryExtensions.SingleOrDefaultAsync<T>(IQueryable<T>, Expression<Func<T, Boolean>>, CancellationToken) Method

Asynchronously gets the object from a selection if only one object in the selection meets the specified requirements. If the selection is empty, returns a default value for <T>. If the selection has more than one of such elements, throws an exception.

Namespace: DevExpress.Xpo

Assembly: DevExpress.Xpo.v18.2.dll

Declaration

C#

public static Task<T> SingleOrDefaultAsync<T>(
    this IQueryable<T> query,
    Expression<Func<T, bool>> predicate,
    CancellationToken cancellationToken = default(CancellationToken)
)

VB.NET

<ExtensionAttribute>
Public Shared Function SingleOrDefaultAsync(Of T)(
    query As IQueryable(Of T),
    predicate As Expression(Of Func(Of T, Boolean)),
    cancellationToken As CancellationToken = Nothing
) As Task(Of T)

Parameters

Name	Type	Description
query	IQueryable<T>	An XPQuery<T> that specifies a selection of persistent objects.
predicate	Expression<Func<T, Boolean>>	An expression which determines requirements the persistent object needs to meet.

Optional Parameters

Name	Type	Default	Description
cancellationToken	CancellationToken	*null*	A CancellationToken object that delivers a cancellation notice to the running operation.

Type Parameters

Name
T

Returns

Type	Description
Task<T>	A Task that returns that returns one object if this is the only object in a selection to meet the specified requirements.