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.NET Framework 4.5.2+
.NET Framework 4.5.2+
.NET Standard 2.0+

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

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

Namespace: DevExpress.Xpo

Assembly: DevExpress.Xpo.v19.2.dll

Declaration

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

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.

equalityComparer IEqualityComparer<TKey>

A function that returns a result value for each persistent object.

cancellationToken CancellationToken

A CancellationToken object that delivers a cancellation notice to the running operation.

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.

equalityComparer IEqualityComparer<TKey>

A function that returns a result value for each persistent object.

cancellationToken CancellationToken

A CancellationToken object that delivers a cancellation notice to the running operation.

Returns

Type Description
Task<ILookup<TKey, T>>

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

Returns

Type Description
Task<ILookup<TKey, T>>

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

Type Parameters

Name Description
T
TKey

Type Parameters

Name Description
T
TKey
See Also