EF架构~真正被封装的排序方法,支持多列排序

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对于linq to sql 和linq to entity来说,当你把获取数据的方法封装了之后,总觉得还缺点什么,想了之后,应该是排序,但看了微软的orchard项目之后,觉得它的排序封装的并不好,而且还有多列排序的问题,所以,我自己又改进了一下,首先提出一个与分层无关的IOrderable接口的概念,它是为了让WEB,BLL,DATA层之间解耦的,其次增加了ThenAsc和ThenDesc让它们支持多列排序,orchard项目里,之前是使用参数来实现的,最多支持3列排序,而且不支持升降混排的情况,呵呵。

看一个IOrderable接口

 /// <summary>
    /// 排序规范
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public interface IOrderable<T>
    {
        /// <summary>
        /// 递增
        /// </summary>
        /// <typeparam name="TKey"></typeparam>
        /// <param name="keySelector"></param>
        /// <returns></returns>
        IOrderable<T> Asc<TKey>(global::System.Linq.Expressions.Expression<Func<T, TKey>> keySelector);
        /// <summary>
        /// 然后递增
        /// </summary>
        /// <typeparam name="TKey1"></typeparam>
        /// <typeparam name="TKey2"></typeparam>
        /// <param name="keySelector1"></param>
        /// <returns></returns>
        IOrderable<T> ThenAsc<TKey>(Expression<Func<T, TKey>> keySelector);
        /// <summary>
        /// 递减
        /// </summary>
        /// <typeparam name="TKey"></typeparam>
        /// <param name="keySelector"></param>
        /// <returns></returns>
        IOrderable<T> Desc<TKey>(global::System.Linq.Expressions.Expression<Func<T, TKey>> keySelector);
        /// <summary>
        /// 然后递减
        /// </summary>
        /// <typeparam name="TKey"></typeparam>
        /// <param name="keySelector"></param>
        /// <returns></returns>
        IOrderable<T> ThenDesc<TKey>(Expression<Func<T, TKey>> keySelector);
        /// <summary>
        /// 排序后的结果集
        /// </summary>
        global::System.Linq.IQueryable<T> Queryable { get; }
    }

OK,下面是为接口的一个实现,这个实现我是放在Data层的,因为它是与ORM架构有关的,可能你的linq与ado.net的排序实现是不同的,所以,不能放在entity层,我的习惯是,所有linq特有的都放在linq架构的Data层(如,IQueryable,这就是linq特有的,而list,IEnumerable等扩展应该放在entity层)

namespace EntityFrameworks.Data.Core
{
    /// <summary>
    /// Linq架构里对集合排序实现
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public class Orderable<T> : IOrderable<T>
    {
        private IQueryable<T> _queryable;

        /// <summary>
        /// 排序后的结果集
        /// </summary>
        /// <param name="enumerable"></param>
        public Orderable(IQueryable<T> enumerable)
        {
            _queryable = enumerable;
        }

        /// <summary>
        /// 排序之后的结果集
        /// </summary>
        public IQueryable<T> Queryable
        {
            get { return _queryable; }
        }
        /// <summary>
        /// 递增
        /// </summary>
        /// <typeparam name="TKey"></typeparam>
        /// <param name="keySelector"></param>
        /// <returns></returns>
        public IOrderable<T> Asc<TKey>(Expression<Func<T, TKey>> keySelector)
        {
            _queryable = (_queryable as IOrderedQueryable<T>)
                .OrderBy(keySelector);
            return this;
        }
        /// <summary>
        /// 然后递增
        /// </summary>
        /// <typeparam name="TKey"></typeparam>
        /// <param name="keySelector"></param>
        /// <returns></returns>
        public IOrderable<T> ThenAsc<TKey>(Expression<Func<T, TKey>> keySelector)
        {
            _queryable = (_queryable as IOrderedQueryable<T>)
                .ThenBy(keySelector);
            return this;
        }
        /// <summary>
        /// 递减
        /// </summary>
        /// <typeparam name="TKey"></typeparam>
        /// <param name="keySelector"></param>
        /// <returns></returns>
        public IOrderable<T> Desc<TKey>(Expression<Func<T, TKey>> keySelector)
        {
            _queryable = _queryable
                .OrderByDescending(keySelector);
            return this;
        }
        /// <summary>
        /// 然后递减
        /// </summary>
        /// <typeparam name="TKey"></typeparam>
        /// <param name="keySelector"></param>
        /// <returns></returns>
        public IOrderable<T> ThenDesc<TKey>(Expression<Func<T, TKey>> keySelector)
        {
            _queryable = (_queryable as IOrderedQueryable<T>)
                .ThenByDescending(keySelector);
            return this;
        }
    }
}

而这个排序的方法,可以单独被BLL层使用,自己去组装它,也可以在Data层提供的GetModel()方法里直接使用,因为我的架构里已经有排序功能拟合到GetModel方法里了,看代码:

      public IQueryable<TEntity> GetModel(Action<IOrderable<TEntity>> orderBy)
        {
            var linq = new Orderable<TEntity>(GetModel());
            orderBy(linq);
            return linq.Queryable;
        }

如果在其它层调用,可以自己去实例化Action<IOrderable<TEntity>>这个对象,如代码:

       backgroundEntities1 db = new backgroundEntities1();
            DbContextRepository<WebManageUsers> user = new DbContextRepository<WebManageUsers>(db);
            Action<IOrderable<WebManageUsers>> orderBy = query => query.Asc(j => j.DepartmentID)
                                                                       .ThenDesc(j => j.ManageUserID);
            user.GetModel(orderBy).ToList().ForEach(k =>
            {
                Console.WriteLine("部门:" + k.DepartmentID + ",用户 :" + k.ManageUserID);
            });

 上面的代码是先对DepartmentID进行升序,再对ManageUserID进行降序,看一下结果如图:

 

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posted @ 2014-01-05 14:35  张占岭  阅读(12219)  评论(9编辑  收藏  举报