Session.PreFetchAsync<T>(IEnumerable<T>, CancellationToken, String[]) Method

Asynchronously forces associated collection data loading and delayed property loading for specified parent objects.

Namespace: DevExpress.Xpo

Assembly: DevExpress.Xpo.v24.1.dll

NuGet Packages: DevExpress.Win.PivotGrid, DevExpress.Win.TreeMap, DevExpress.Xpo

NuGet Package: DevExpress.Xpo

Declaration

C#

public Task PreFetchAsync<T>(
    IEnumerable<T> objects,
    CancellationToken cancellationToken,
    params string[] propertyPaths
)

VB.NET

Public Function PreFetchAsync(Of T)(
    objects As IEnumerable(Of T),
    cancellationToken As CancellationToken,
    ParamArray propertyPaths As String()
) As Task

Parameters

Name	Type	Description
objects	IEnumerable<T>	An IEnumerable list of parent objects.
cancellationToken	CancellationToken	A CancellationToken object that delivers a cancellation notice to the running operation.
propertyPaths	String[]	An array of strings that are the collection property and delayed property names, or property paths (e.g, “ChildCollection.AnotherChildCollection”).

Type Parameters

Name	Description
T	The type of elements in the list of parent objects.

Returns

Type	Description
Task	A Task that forces associated collection data loading and delayed property loading for specified parent objects.

Remarks

By default, data is loaded automatically when you access a nested collection or delayed property for the first time. When the PreFetchAsync<T> method is called, all associated collection data and delayed properties are loaded at once for specified parent objects. No additional SQL queries for this data will be will be performed later.

C#

using System.Threading;
using DevExpress.Xpo;
// ...
CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
CancellationToken cancellationToken = cancellationTokenSource.Token;
XPCollection<Person> people = new XPCollection<Person>(session);
await session.PreFetchAsync<Person>(people, cancellationToken, nameof(PhoneNumbers));

VB.NET

Imports System.Threading
Imports DevExpress.Xpo
' ...
Private cancellationTokenSource As New CancellationTokenSource()
Private cancellationToken As CancellationToken = cancellationTokenSource.Token
Private people As New XPCollection(Of Person)(session)
Await session.PreFetchAsync(Of Person)(people, cancellationToken, NameOf(PhoneNumbers))