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; }

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。