Session.PreFetch<T>(IEnumerable<T>, String, IEnumerable) Method

Enforces loading data for associated collections.

Namespace: DevExpress.Xpo

Assembly: DevExpress.Xpo.v23.2.dll

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

NuGet Package: DevExpress.Xpo

Declaration

C#

public void PreFetch<T>(
    IEnumerable<T> objects,
    string collectionInObjects,
    IEnumerable collectionsContent
)

VB.NET

Public Sub PreFetch(Of T)(
    objects As IEnumerable(Of T),
    collectionInObjects As String,
    collectionsContent As IEnumerable
)

Parameters

Name	Type	Description
objects	IEnumerable<T>	An IEnumerable list of parent objects.
collectionInObjects	String	A string which is the name of the associated collection property.
collectionsContent	IEnumerable	An IEnumerable list of the collection’s content. If the collectionInObjects data was previously loaded, you can avoid reloading it by passing the loaded data to the collectionsContent parameter. Note that if this parameter does not contain a part of the collection’s content, this part will not be loaded from a database.

Type Parameters

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

Remarks

By default, data is loaded automatically when you access a nested collection for the first time. When the PreFetch<T> method is called, all data for the specified collection is loaded at once. No additional SQL queries for this data will be performed later.

C#

using DevExpress.Xpo;
using DevExpress.Xpo.Metadata;
// ...
XPCollection<Person> people = new XPCollection<Person>(session);
XPCollection<PhoneNumber> phoneNumbers = new XPCollection<PhoneNumber>(session);
session.PreFetch<Person>(people, nameof(PhoneNumbers), phoneNumbers);

VB.NET

Imports DevExpress.Xpo
Imports DevExpress.Xpo.Metadata
' ...
Private people As New XPCollection(Of Person)(session)
Private phoneNumbers As New XPCollection(Of PhoneNumber)(session)
session.PreFetch(Of Person)(people, NameOf(PhoneNumbers), phoneNumbers)