entity-framework – 实体框架 – 删除Oracle 10g中的实体{由于

这是SQL代码：

-- Create table
create table TESTTABLE
(
  MODULE_UNIQUE_ID VARCHAR2(32) not null,PANEL_STATUS     VARCHAR2(8) not null
)
tablespace SYSTEM
  pctfree 10
  pctused 40
  initrans 1
  maxtrans 255
  storage
  (
    initial 64K
    minextents 1
    maxextents unlimited
  );
-- Create/Recreate primary,unique and foreign key constraints 
alter table TESTTABLE
  add constraint TESTTABLE_PK_01 unique (MODULE_UNIQUE_ID)
  using index 
  tablespace SYSTEM
  pctfree 10
  initrans 2
  maxtrans 255
  storage
  (
    initial 64K
    minextents 1
    maxextents unlimited
  );

我创建了简单的存储库类：

public interface IRepository<TEntity,TCtx>
{
    TCtx Session { get;}
    void Add(TEntity entity);
    void AddOrAttach(TEntity entity);
    void Delete(TEntity entity);
    int Save();
    TEntity SelectByKey(string colName,string key);
}

public class Repository<TEntity,TCtx> : IRepository<TEntity,TCtx>,IDisposable
    where TEntity : EntityObject
    where TCtx : ObjectContext
{
    #region Private fields

    private TCtx _ctx;
    private string _keyProperty = "ID";

    public int Save()
    {
        return _ctx.SaveChanges();
    }

   public TEntity SelectByKey(string colName,string key)
    {
        KeyProperty = colName;

        // First we define the parameter that we are going to use the clause.
        var xParam = Expression.Parameter(typeof(TEntity),typeof(TEntity).Name);
        MemberExpression leftExpr = Expression.Property(xParam,KeyProperty);
        Expression rightExpr = Expression.Constant(key);
        BinaryExpression binaryExpr = Expression.Equal(leftExpr,rightExpr);

        //Create Lambda Expression for the selection
        Expression<Func<TEntity,bool>> lambdaExpr = Expression.Lambda<Func<TEntity,bool>>
            (binaryExpr,new ParameterExpression[] { xParam });

        //Searching ....
        //IList<TEntity> resultCollection = ((IRepository<TEntity,TCtx>)this).SelectAll(new Specification<TEntity>(lambdaExpr));

        //if (null != resultCollection && resultCollection.Count() > 0)
        //{
        //    //return valid single result
        //    return resultCollection.First();
        //}
        //return null;

        return ((IRepository<TEntity,TCtx>) this)
            .SelectAll(new Specification<TEntity>(lambdaExpr)).FirstOrDefault();
    }

    public void Delete(TEntity entity)
    {
        _ctx.DeleteObject(entity);

    }

 }

问题是我先选择一些实体,然后我要删除.
选择适用于Oracle DB的工作.问题是更新或删除命令.

var _repo = new Repository<TESTTABLE,Entities>(
            new Entities(ConfigurationManager.ConnectionStrings["Entities"]
                          .ConnectionString));

    var obj = _repo.SelectByKey("MODULE_UNIQUE_ID","22222");
    _repo.Delete(obj);
    _repo.Save();

我得到这个例外：

{“An error occurred while updating the entries. See the inner
exception for details.”}

内部异常：

{“Operation is not valid due to the current state of the object.”}

堆栈跟踪：

at
System.Data.Mapping.Update.Internal.UpdateTranslator.CreateCommand(DbModificationCommandTree
commandTree) at
System.Data.Mapping.Update.Internal.DynamicUpdateCommand.CreateCommand(UpdateTranslator
translator,Dictionary2 identifierValues) at
System.Data.Mapping.Update.Internal.DynamicUpdateCommand.Execute(UpdateTranslator
translator,EntityConnection connection,Dictionary2
identifierValues,List`1 generatedValues) at
System.Data.Mapping.Update.Internal.UpdateTranslator.Update(IEntityStateManager
stateManager,IEntityAdapter adapter)

我再次测试了我的存储库类MS SQL数据库它运行良好.

什么可能导致这个问题？

解决方法

_context.ObjectStateManager.ChangeObjectState(entity,EntityState.Modified);

>加载/附加实体
>将其标记为已更改/已跟踪
>从上下文删除/删除
>保存

MSDN Notes http://msdn.microsoft.com/en-us/library/system.data.objects.objectstatemanager.aspx

相关邮政ObjectContext tracking changes in Entity Framwwork

出于性能原因,您可以加载没有更改跟踪的对象

（编辑：李大同）

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