Question

此代码在ef 4.0中运行良好，但我刚刚升级到ef 5.0并在调用保存更改时出现以下错误

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.Objects;
using OSPos.DBContext;

namespace OSPos.OSPosContext
{
    public abstract class ContextBase
    {
        public abstract bool SaveChanges();

        protected bool SaveChanges(ObjectContext context)
        {
            try
            {
                int i = context.SaveChanges();
                if (i == 0)
                    return false;

                return true;
            }
            catch (Exception ex)
            {
                throw new EntityContextException("SaveChanges failed.", ex);
            }

        }

        public abstract void DeleteObject(object entity);

        protected void DeleteObject(ObjectContext context, object entity)
        {
            try
            {
                context.DeleteObject(entity);
            }
            catch (Exception ex)
            {
                throw new EntityContextException("DeleteObject failed.", ex);
            }
        }

        protected static string pamsConnectionString;

        public static string PamsConnectionString
        {
            set { pamsConnectionString = value; }
        }

        protected static string pamssysdbfConnectionString;

        public static string PamssysdbfConnectionString
        {
            set { pamssysdbfConnectionString = value; }
        }

        #region Encryption Fields

        public static string encryptionServiceUrl;
        public static bool encryptionEnabled = false;
        private static string encryptionTicket;

        #endregion
    }
}

我的通话类如下

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml.Linq;
using System.ComponentModel;
using System.Text.RegularExpressions;
using CMSNIDataobjects.Lookups;
using System.ComponentModel.DataAnnotations.Schema;
using System.ComponentModel.DataAnnotations;
using System.Data.Entity;
using OSPos.OSPosContext;

namespace OSPos.OSPosContext
{
    public class cmsContext : ContextBase
    {
        private  OSPosEntities1  _OsPosEntities;
        protected OSPosEntities1 OSPosEntities
        {
             get
             {
                 if (_OsPosEntities == null)
                 {
                 // try
                 // {
                        _OsPosEntities = new OSPosEntities1();//knowledgebaseEntities1(@"metadata=res://*/KnowledgeBase.csdl|res://*/KnowledgeBase.ssdl|res://*/KnowledgeBase.msl;provider=System.Data.SqlClient;provider connection string=&quot;data source=DAVID_BUCKLEY\DBSQLSERVER28R2;initial catalog=knowledgebase;integrated security=True;MultipleActiveResultSets=True;App=EntityFramework&quot;");}
                 //}
                 //catch (Exception ex)
                 //{
                 //    throw new EntityContextException("cmsEntities object could not be created.", ex);
                 //}
                }
                return _OsPosEntities;
            }
        }

        public override int  SaveChanges()
        {
            return base.SaveChanges();
            //this is where i am getting the error in reference to abstract class
        }

        public override void DeleteObject(object entity)
        {
        }
    }
}

Answer 1

类ContextBase是抽象的，必须重写。你做到了。但方法SaveChanges()也是抽象的，也必须被覆盖。

如果ContextBase是您的发明，那么这些变化可能会有所帮助。

如果您想要求覆盖，请离开以下行：

public abstract bool SaveChanges();

...并完全删除基本方法。然后只需在cmsContext中提供覆盖。否则，将其删除并将基本方法更改为virtual：

protected virtual bool SaveChanges(ObjectContext context)
{
    try
    {
        int i = context.SaveChanges();
        if (i == 0)
            return false;

        return true;
    }
    catch (Exception ex)
    {
        throw new EntityContextException("SaveChanges failed.", ex);
    }
}

对于您显然想要使用的其他方法DeleteObject执行相同操作。

只有当您需要派生类中与基类不同的特定功能时，才能使这些virtual具有覆盖的灵活性。否则，您只需使用最初尝试的base.SaveChanges()来电即可获得BaseContext中的内容。

保存更改错误无法调用抽象类c＃

1 个答案: