是EntityReference.Load检查EntityReference.IsLoaded?
-
20-09-2019 - |
题
您好我想知道如果 EntityReference.Load
方法包括
If Not ref.IsLoaded Then ref.Load()
我的问题基本上是:
Dim person = Context.Persons.FirstOrDefault
person.AddressReference.Load()
person.AddressReference.Load() 'Does it do anything?
解决方案
它再次装入。我通过探查证实这一点,它显示了两个查询。默认合并选项是MergeOption.AppendOnly,它不会再次查询阻止。从反射器的代码:
public override void Load(MergeOption mergeOption)
{
base.CheckOwnerNull();
ObjectQuery<TEntity> query = base.ValidateLoad<TEntity>(mergeOption, "EntityReference");
base._suppressEvents = true;
try
{
List<TEntity> collection = new List<TEntity>(RelatedEnd.GetResults<TEntity>(query));
if (collection.Count > 1)
{
throw EntityUtil.MoreThanExpectedRelatedEntitiesFound();
}
if (collection.Count == 0)
{
if (base.ToEndMember.RelationshipMultiplicity == RelationshipMultiplicity.One)
{
throw EntityUtil.LessThanExpectedRelatedEntitiesFound();
}
if ((mergeOption == MergeOption.OverwriteChanges) || (mergeOption == MergeOption.PreserveChanges))
{
EntityKey entityKey = ObjectStateManager.FindKeyOnEntityWithRelationships(base.Owner);
EntityUtil.CheckEntityKeyNull(entityKey);
ObjectStateManager.RemoveRelationships(base.ObjectContext, mergeOption, (AssociationSet) base.RelationshipSet, entityKey, (AssociationEndMember) base.FromEndProperty);
}
base._isLoaded = true;
}
else
{
base.Merge<TEntity>(collection, mergeOption, true);
}
}
finally
{
base._suppressEvents = false;
}
this.OnAssociationChanged(CollectionChangeAction.Refresh, null);
}
其他提示
就为大家有没有发现接受的答案参考,下面是我为我的当前项目创建的扩展方法。
using System.Data.Objects.DataClasses;
namespace ProjectName
{
public static class EntityFrameworkExtensions
{
public static void EnsureLoaded<TEntity>(this EntityReference<TEntity> reference)
where TEntity : class, IEntityWithRelationships
{
if (!reference.IsLoaded)
reference.Load();
}
}
}
和用法:
Patient patient = // get patient
patient.ClinicReference.EnsureLoaded();
patient.Clinic.DoStuff();
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