EntityFramework实现指定字段的通用赋值

1、背景

平常我们在建表的时候一般除了业务字段，还会加上如Create_Date 、Create_User 、Update_Date 、Update_User这样的通用字段 ；

   public Nullable<System.DateTime> Create_Date { get; set; }        public string Create_User { get; set; }        public Nullable<System.DateTime> Update_Date { get; set; }        public string Update_User { get; set; }

这样的公共字段，主要用于数据变更的核查，那么在创建或者修改的时候，

一般的赋值方式是这样的???????

      BQoolCommon_Inner_Country_Timezone model = new BQoolCommon_Inner_Country_Timezone();            model.Create_Date = DateTime.UtcNow;            model.Create_User = "test";            model.Update_Date = DateTime.UtcNow;            model.Update_User = "test";

直接在对象实体里面直接赋值，但是这样就会造成很多的重复工作，说实在的写得多了会烦，也容易出错；

2、实现

那么有没有偷懒的办法呢，答案是肯定的。

下面我们看下如何在EntityFramework实现指定通用字段的赋值；

2.1首先是添加数据???????

 public void Create(TEntity instance)        {
               if (instance == null)            {
                   throw new ArgumentNullException("instance");            }            else            {
                   _context.Set<TEntity>().Add(instance);                SetCreate(instance);                SaveChanges(instance);            }        }

通过反射方式，对指定的字段赋值???????

   private void SetCreate(TEntity instance)        {
               var attachedEntry = _context.Entry(instance);
            PropertyInfo getProperty(string propertyName)            {
                   return attachedEntry.Entity.GetType().GetProperty(propertyName);            }
            //Create_User            if (getProperty("Create_User") != null && string.IsNullOrEmpty(getProperty("Create_User").GetValue(attachedEntry.Entity) as string))            {
                   getProperty("Create_User").SetValue(attachedEntry.Entity, _user);            }            else if (getProperty("CreateUser") != null && string.IsNullOrEmpty(getProperty("CreateUser").GetValue(attachedEntry.Entity) as string))            {
                   getProperty("CreateUser").SetValue(attachedEntry.Entity, _user);            }
            //Create_Date            if (getProperty("Create_Date") != null)            {
                   DateTime? createDate = getProperty("Create_Date").GetValue(attachedEntry.Entity) as DateTime?;                if (createDate == null || createDate == DateTime.MinValue)                {
                       getProperty("Create_Date").SetValue(attachedEntry.Entity, GetDBTime());                }            }            else if (getProperty("CreateDate") != null && getProperty("CreateDate").GetValue(attachedEntry.Entity) as DateTime? == null)            {
                   DateTime? createDate = getProperty("CreateDate").GetValue(attachedEntry.Entity) as DateTime?;                if (createDate == null || createDate == DateTime.MinValue)                {
                       getProperty("CreateDate").SetValue(attachedEntry.Entity, GetDBTime());                }            }        }

2.2再者是更新操作???????

   public void Update(TEntity instance)        {
               if (instance == null)            {
                   throw new ArgumentNullException("instance");            }            else            {
                   SetUpdate(instance);
                //_context.Entry(instance).State = EntityState.Modified;                _context.Set<TEntity>().AddOrUpdate(instance);                SaveChanges(instance);            }        }

如上方式???????

   public void SetUpdate(TEntity instance)        {
               if (instance == null)            {
                   throw new ArgumentNullException("instance");            }            else            {
                   var attachedEntry = _context.Entry(instance);
                if (attachedEntry.Entity.GetType().GetProperty("Update_User") != null && !string.IsNullOrEmpty(_user))                {
                       attachedEntry.Entity.GetType().GetProperty("Update_User").SetValue(attachedEntry.Entity, _user);                }                else if (attachedEntry.Entity.GetType().GetProperty("UpdateUser") != null && !string.IsNullOrEmpty(_user))                {
                       attachedEntry.Entity.GetType().GetProperty("UpdateUser").SetValue(attachedEntry.Entity, _user);                }
                if (attachedEntry.Entity.GetType().GetProperty("Update_Date") != null)                {
                       attachedEntry.Entity.GetType().GetProperty("Update_Date").SetValue(attachedEntry.Entity, GetDBTime());                }                else if (attachedEntry.Entity.GetType().GetProperty("UpdateDate") != null)                {
                       attachedEntry.Entity.GetType().GetProperty("UpdateDate").SetValue(attachedEntry.Entity, GetDBTime());                }            }        }

最后大功告成，再也不用每次都赋值一次了。