XPQueryExtensions.ToLookupAsync<T, TKey, TElement>(IQueryable<T>, Func<T, TKey>, Func<T, TElement>, IEqualityComparer<TKey>, CancellationToken) Method

Asynchronously enumerates a query and uses a key selector, an element selector and an comparer to construct a Lookup<TKey,TElement>.

Namespace: DevExpress.Xpo

Assembly: DevExpress.Xpo.v25.1.dll

NuGet Package: DevExpress.Xpo

Declaration

C#

public static Task<ILookup<TKey, TElement>> ToLookupAsync<T, TKey, TElement>(
    this IQueryable<T> query,
    Func<T, TKey> keySelector,
    Func<T, TElement> elementSelector,
    IEqualityComparer<TKey> equalityComparer,
    CancellationToken cancellationToken = default(CancellationToken)
)

VB.NET

<ExtensionAttribute>
Public Shared Function ToLookupAsync(Of T, TKey, TElement)(
    query As IQueryable(Of T),
    keySelector As Func(Of T, TKey),
    elementSelector As Func(Of T, TElement),
    equalityComparer As IEqualityComparer(Of TKey),
    cancellationToken As CancellationToken = Nothing
) As Task(Of ILookup(Of TKey, TElement))

Parameters

Name	Type	Description
query	IQueryable<T>	An XPQuery<T> to be enumerated.
keySelector	Func<T, TKey>	A function that acquires each persistent object’s key.
elementSelector	Func<T, TElement>	A function that returns a result value for each persistent object.
equalityComparer	IEqualityComparer<TKey>	A function that returns a result value for each persistent object.

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
TKey
TElement

Returns

Type	Description
Task<ILookup<TKey, TElement>>	A Task that returns a Lookup<TKey,TElement>.