Session.PreFetch(IEnumerable, XPMemberInfo, IEnumerable) Method

Enforces loading data for an associated collection.

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(
    IEnumerable objects,
    XPMemberInfo collectionInObjects,
    IEnumerable collectionsContent
)

VB.NET

Public Sub PreFetch(
    objects As IEnumerable,
    collectionInObjects As XPMemberInfo,
    collectionsContent As IEnumerable
)

Parameters

Name	Type	Description
objects	IEnumerable	An IEnumerable list of parent objects.
collectionInObjects	XPMemberInfo	An XPMemberInfo object that provides metadata information for an associated collection.
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.

Remarks

By default, data is loaded automatically when you access a nested collection for the first time. When the PreFetch 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);
XPMemberInfo phoneNumbersInfo = session.GetClassInfo(typeof(Person)).GetMember(nameof(PhoneNumbers));
session.PreFetch(people, phoneNumbersInfo, 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)
Private phoneNumbersInfo As XPMemberInfo = _
    session.GetClassInfo(GetType(Person)).GetMember(NameOf(PhoneNumbers))
session.PreFetch(people, phoneNumbersInfo, phoneNumbers)