我们在后台代码里面操作Entity的时候，基本上是这样写的：

/* 创建者：菜刀居士的博客
 * 创建日期：2014年07月5号
 */

 namespace Net.CRM.Entity
{
    using System;
    using Microsoft.Xrm.Sdk;

    /// <summary>
    /// 基本模式---Entity
    /// </summary>
    public class EntityDemo
    {
        public void Run(Entity entity)
        {
            if (IsNotNull(entity,"new_int"))
            {
                //获取int类型的字段的值
                int new_int = entity.GetAttributeValue<int>("new_int");
            }
            if (IsNotNull(entity, "new_string"))
            {
                //获取string类型的字段的值
                string new_string = entity.GetAttributeValue<string>("new_string");
            }
            if (IsNotNull(entity, "new_float"))
            {
                //获取float类型的字段的值
                float new_float = entity.GetAttributeValue<float>("new_float");
            }
            if (IsNotNull(entity, "new_money"))
            {
                //获取Money(货币)类型的字段的值
                decimal new_money = entity.GetAttributeValue<Money>("new_money").Value;
            }
            if (IsNotNull(entity, "new_picklist"))
            {
                //获取OptionSetValue(下拉框)类型的字段的值
                int new_picklist = entity.GetAttributeValue<OptionSetValue>("new_picklist").Value;
            }
            if (IsNotNull(entity, "new_lookup"))
            {
                //获取EntityReference(引用字段)类型的字段的值
                EntityReference new_lookup = entity.GetAttributeValue<EntityReference>("new_lookup");
            }
        }

        /// <summary>
        /// 判断实体的某个字段是否为空
        /// </summary>
        /// <param name="entity">实体</param>
        /// <param name="name">字段名称</param>
        public bool IsNotNull(Entity entity,string name)
        {
            return entity.Contains(name) && entity.Attributes[name] != null;
        }
    }
}

这样写，是正确的，但是，很繁琐，下面是快速的写法：

 /* 创建者：菜刀居士的博客
 * 创建日期：2014年07月5号
 */

namespace Net.CRM.Entity
{
    using System;
    using Microsoft.Xrm.Sdk;

    /// <summary>
    /// 快速开发---Entity
    /// </summary>
    public class EntityQuickDemo
    {
        public void Run(Entity entity)
        {
            if (entity.IsNotNull("new_int"))
            {
                //获取int类型的字段的值
                int new_int = entity.ToInt("new_int");
            }
            if (entity.IsNotNull("new_string"))
            {
                //获取string类型的字段的值
                string new_string = entity.ToString("new_string");
            }
            if (entity.IsNotNull("new_float"))
            {
                //获取float类型的字段的值
                float new_float = entity.ToFloat("new_float");
            }
            if (entity.IsNotNull("new_money"))
            {
                //获取Money(货币)类型的字段的值
                decimal new_money = entity.ToMoney("new_money");
            }
            if (entity.IsNotNull("new_picklist"))
            {
                //获取OptionSetValue(下拉框)类型的字段的值
                int new_picklist = entity.ToOpInt("new_picklist");
            }
            if (entity.IsNotNull("new_lookup"))
            {
                //获取EntityReference(引用字段)类型的字段的值
                EntityReference new_lookup = entity.ToEr("new_lookup");
            }
        }
    }

    /// <summary>
    /// 扩展方法
    /// </summary>
    public static class EntityFunction
    {
        /// <summary>
        /// Int
        /// </summary>
        public static int ToInt(this Entity entity, string name)
        {
           return entity.GetAttributeValue<int>(name);
        }

        /// <summary>
        /// string
        /// </summary>
        public static string ToString(this Entity entity, string name)
        {
            return entity.GetAttributeValue<string>(name);
        }

        /// <summary>
        /// float
        /// </summary>
        public static float ToFloat(this Entity entity, string name)
        {
            return entity.GetAttributeValue<float>(name);
        }

        /// <summary>
        /// Money
        /// </summary>
        public static decimal ToMoney(this Entity entity, string name)
        {
            return entity.GetAttributeValue<Money>(name).Value;
        }

        /// <summary>
        /// OptionSetValue
        /// </summary>
        public static int ToOpInt(this Entity entity, string name)
        {
            return entity.GetAttributeValue<OptionSetValue>(name).Value;
        }

        /// <summary>
        /// EntityReference
        /// </summary>
        public static EntityReference ToEr(this Entity entity, string name)
        {
            return entity.GetAttributeValue<EntityReference>(name);
        }

        public static T GetAttributeValue<T>(this Entity entity, string name)
        {
            if (entity.IsNotNull(name))
            {
                return entity.GetAttributeValue<T>(name);
            }
            return default(T);
        }

        /// <summary>
        /// 判断实体的某个字段是否为空
        /// </summary>
        /// <param name="entity">实体</param>
        /// <param name="name">字段名称</param>
        public static bool IsNotNull(this Entity entity, string name)
        {
            return entity.Contains(name) && entity.Attributes[name] != null;
        }
    }
}