SqlHelper简单实现（通过Expression和反射）4.对象反射Helper类

ObjectHelper的主要功能有：

1.通过反射获取Entity的实例的字段值和表名，跳过自增键并填入Dictionary<string,string>中。

 namespace RA.DataAccess.Common
 {
     internal static class ObjectHelper
     {
         /// <summary>
         /// 获取Entity实例的字段名和值（用于更新和插入数据）
         /// </summary>
         /// <param name="obj"></param>
         /// <returns></returns>
         public static Dictionary<string,object> GetKeyValue(object obj){
             var data = new Dictionary<string, object>();
             foreach (var i in obj.GetType().GetProperties())
             {
                 if (IsContainsAttribute(i.GetCustomAttributes(true))) continue;
                 var value = obj.GetType().GetProperty(i.Name).GetValue(obj, null);
                 data.Add(i.Name, value);
             }
             return data;
         }

         /// <summary>
         /// 是否包含自增键，在插入表时可以跳过自增键的设置
         /// </summary>
         /// <param name="attrs"></param>
         /// <returns></returns>
         private static bool IsContainsIndentityAttribute(IEnumerable<object> attrs)
         {
             return attrs.OfType<IdentityAttribute>().Any();
         }
     }
 }

2.通过反射，为实例赋值，此处只是列举了常用的数据类型：int，string和DataTime

         /// <summary>
         /// 为通过反射生成的实例赋值
         /// </summary>
         /// <typeparam name="T">实例的类型</typeparam>
         /// <param name="obj">实例</param>
         /// <param name="value">值</param>
         /// <param name="key">成员名称</param>
         public static void SetValue<T>(ref T obj, Object value, String key) where T : class
         {
             var property = obj.GetType().GetProperty(key);
             var type = property.PropertyType.Name;
             if (value is System.DBNull)
             {
                 property.SetValue(obj, null, null);
                 return;
             }
             switch (type)
             {
                 case "Int32":
                     property.SetValue(obj, int.Parse(value.ToString()), null);
                     break;
                 case "String":
                     property.SetValue(obj, value.ToString(), null);
                     break;
                 case "DateTime":
                     property.SetValue(obj, (DateTime)value, null);
                     break;
                 default:
                     property.SetValue(obj, value, null);
                     break;
             }
         }