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我一直在.NET 4.0解決方案中使用實體框架幾周。這是EF 4.3.1。我首先創建了數據庫模式，並使用「EF4.x DbContext生成器」模板生成了我的實體對象。無法使用實體框架設置實體類型的字段/屬性4.3.1
我在模式中有三個表格，並且它使用簡單的CRUD方法都可以正常工作。
我現在添加了第四個表「主題」，它具有對現有表「SourceUri」的外鍵引用，使得SourceUri可以具有0多個主題，並且主題只有一個SourceUri。
我更新了我的edmx模型，它看起來正確。但是，不管我怎麼努力，我似乎無法做到以下幾點：
- 添加新SourceUri記錄
- 添加一個或多個科目爲新SourceUri
這是我的代碼我正在嘗試。您可以看到我經常保存上下文，但最初我只是在方法結束時保存一次更改。
/// <summary>
/// Adds a new Source URI to the system
/// </summary>
/// <param name="sourceUri">The source URI to add</param>
/// <param name="subjectNames">List of subjects for this source URI, in order</param>
/// <returns>The added source URI</returns>
public SourceUri AddSourceUri(SourceUri sourceUri, IList<string> subjectNames)
{
try
{
_logger.Debug("Adding new source URI '{0}', with '{1}' subjects.", sourceUri.Uri,
subjectNames != null ? subjectNames.Count : 0);
LogSourceUriDetails(sourceUri, "Adding");
using (var dbContext = GetDbContext())
{
dbContext.SourceUris.Add(sourceUri);
dbContext.SaveChanges(); // this save succeeds
// add the subjects if there are any
if (subjectNames != null)
{
for (int i = 0; i < subjectNames.Count; i++)
{
Subject newSubject = new Subject()
{
DisplayOrder = i,
SourceUriId = sourceUri.SourceUriId,
SubjectText = subjectNames.ElementAt(i).Trim()
};
_logger.Debug("Adding new subject '{0}' to source URI '{1}'.", newSubject.SubjectText,
sourceUri.Uri);
dbContext.Subjects.Add(newSubject); // this line fails
dbContext.SaveChanges();
}
}
_logger.Debug("Successfully added new source URI '{0}' with '{1}' subjects. Source URI ID is '{2}'.",
sourceUri.Uri, subjectNames != null ? subjectNames.Count : 0, sourceUri.SourceUriId);
return sourceUri;
}
}
catch (Exception exception)
{
_logger.ErrorException(string.Format("An error occurred adding new source URI '{0}' with '{1}' subjects.",
sourceUri.Uri, subjectNames != null ? subjectNames.Count : 0), exception);
throw;
}
}
該代碼添加新的SourceUri並保存更改。但是，它無法將新主題添加到數據上下文中。它不會盡力保存這種變化。
唯一的例外是：
Unable to set field/property Subjects on entity type CommentService.DomainObjects.SourceUri. See InnerException for details.
System.Data.Objects.Internal.PocoPropertyAccessorStrategy.CollectionRemove(RelatedEnd relatedEnd, Object value)
System.Data.Objects.Internal.EntityWrapper`1.CollectionRemove(RelatedEnd relatedEnd, Object value)
System.Data.Objects.DataClasses.EntityCollection`1.RemoveFromObjectCache(IEntityWrapper wrappedEntity)
System.Data.Objects.DataClasses.RelatedEnd.Remove(IEntityWrapper wrappedEntity, Boolean doFixup, Boolean deleteEntity, Boolean deleteOwner, Boolean applyReferentialConstraints, Boolean preserveForeignKey)
System.Data.Objects.DataClasses.RelatedEnd.FixupOtherEndOfRelationshipForRemove(IEntityWrapper wrappedEntity, Boolean preserveForeignKey)
System.Data.Objects.DataClasses.RelatedEnd.Remove(IEntityWrapper wrappedEntity, Boolean doFixup, Boolean deleteEntity, Boolean deleteOwner, Boolean applyReferentialConstraints, Boolean preserveForeignKey)
System.Data.Objects.DataClasses.EntityReference`1.Exclude()
System.Data.Objects.DataClasses.RelationshipManager.RemoveRelatedEntitiesFromObjectStateManager(IEntityWrapper wrappedEntity)
System.Data.Objects.ObjectContext.AddObject(String entitySetName, Object entity)
System.Data.Entity.Internal.Linq.InternalSet`1.<>c__DisplayClass5.<Add>b__4()
System.Data.Entity.Internal.Linq.InternalSet`1.ActOnSet(Action action, EntityState newState, Object entity, String methodName)
System.Data.Entity.Internal.Linq.InternalSet`1.Add(Object entity)
System.Data.Entity.DbSet`1.Add(TEntity entity)
CommentService.Business.Managers.SourceUriManager.AddSourceUri(SourceUri sourceUri, IList`1 subjectNames) in C:\Projects\SVN Misc Projects\CommentService\trunk\CommentService.Business\Managers\SourceUriManager.cs:line 152
CommentService.Web.Comment.AddSourceUri(SourceUri sourceUri, IList`1 subjectNames) in C:\Projects\SVN Misc Projects\CommentService\trunk\CommentService.Web\Comment.svc.cs:line 173
SyncInvokeAddSourceUri(Object , Object[] , Object[])
System.ServiceModel.Dispatcher.SyncMethodInvoker.Invoke(Object instance, Object[] inputs, Object[]& outputs)
System.ServiceModel.Dispatcher.DispatchOperationRuntime.InvokeBegin(MessageRpc& rpc)
System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage5(MessageRpc& rpc)
System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage41(MessageRpc& rpc)
System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage4(MessageRpc& rpc)
System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage31(MessageRpc& rpc)
System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage3(MessageRpc& rpc)
System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage2(MessageRpc& rpc)
System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage11(MessageRpc& rpc)
System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage1(MessageRpc& rpc)
System.ServiceModel.Dispatcher.MessageRpc.Process(Boolean isOperationContextSet)
我已經團團此，也見過幾個稍有不同的異常。它們似乎都指向SourceUri對象的Subjects導航屬性以某種方式是隻讀或固定長度（數組？）的事實。
生成的實體類如下所示：
//------------------------------------------------------------------------------
// <auto-generated>
// This code was generated from a template.
//
// Manual changes to this file may cause unexpected behavior in your application.
// Manual changes to this file will be overwritten if the code is regenerated.
// </auto-generated>
//------------------------------------------------------------------------------
namespace CommentService.DomainObjects
{
using System;
using System.Collections.Generic;
public partial class SourceUri
{
public SourceUri()
{
this.Comments = new HashSet<Comment>();
this.Subjects = new HashSet<Subject>();
}
public long SourceUriId { get; set; }
public string Uri { get; set; }
public string Description { get; set; }
public System.DateTime DateCreated { get; set; }
public string AdminUser { get; set; }
public virtual ICollection<Comment> Comments { get; set; }
public virtual ICollection<Subject> Subjects { get; set; }
}
}
//------------------------------------------------------------------------------
// <auto-generated>
// This code was generated from a template.
//
// Manual changes to this file may cause unexpected behavior in your application.
// Manual changes to this file will be overwritten if the code is regenerated.
// </auto-generated>
//------------------------------------------------------------------------------
namespace CommentService.DomainObjects
{
using System;
using System.Collections.Generic;
public partial class Subject
{
public Subject()
{
this.Comments = new HashSet<Comment>();
}
public long SubjectId { get; set; }
public long SourceUriId { get; set; }
public string SubjectText { get; set; }
public int DisplayOrder { get; set; }
public virtual ICollection<Comment> Comments { get; set; }
public virtual SourceUri SourceUri { get; set; }
}
}
爲什麼不這項工作？
快速的事情，我已經檢查列表/試過：
- 數據庫架構看起來是正確的 - 我可以插入記錄與SQL和主鍵，外鍵和身份預期似乎是正確的行爲
- 該模型似乎正確地反映了數據庫模式，包括PK身份（EntityKey = true，StoreGeneratedPattern = Identity）
- 我設法讓EF將數據保存到我的模式中，但是插入數據後引發異常指出上下文可能不同步 - 再次涉及不能更新SourceUri對象的主題導航屬性
- 我已經嘗試將主題添加到dbContext.Subjects集合，並且還添加到SourceUri.Subjects集合。我也嘗試設置主題的SourceUri屬性而不是主題的SourceUriId屬性。
「*請參閱的InnerException瞭解詳細信息。」 *說第一在堆棧跟蹤線。你能做到這一點，並添加內部異常信息到你的問題？ – Slauma 2012-07-16 12:12:17
內部異常爲空。 – 2012-07-16 13:03:30