/// <summary>
/// 分页查询方法扩展二
/// </summary>
/// <param name="query">IQueryable对象</param>
/// <param name="index">索引，最小值为1</param>
/// <param name="pageSize">分页大小</param>
/// <param name="wheres">过滤表达式</param>
/// <param name="funOrderby">排序表达式,支持多重排序,此表达式使用，扩展的方式进行</param>
/// <param name="selector">选择表达式</param>
/// <typeparam name="TEntity">业务实体类型</typeparam>
/// <typeparam name="TResult">结果集类型</typeparam>
/// <returns>返回分页数据</returns>
/// <exception cref="ArgumentNullException">当选择条件selector为null时，抛出此异常</exception>
public static PageInfo <TResult> Query <TEntity, TResult>(this IQueryable <TEntity> query, int index,
int pageSize,
List <Expression <Func <TEntity, bool> > > wheres,
Func <IQueryable <TEntity>, IQueryable <TEntity> > funOrderby,
Func <IQueryable <TEntity>, List <TResult> > selector)
{
if (selector == null)
{
throw new ArgumentNullException("selector");
}
if (funOrderby == null)
{
throw new ArgumentNullException("funOrderby");
}
PageInfo.CheckPageIndexAndSize(ref index, ref pageSize);
IQueryable <TEntity> queryable = query;
if (wheres != null)
{
wheres.ForEach(p =>
{
if (p != null)
{
queryable = queryable.Where(p);
}
});
}
int count = queryable.Count();
PageInfo.CheckPageIndexAndSize(ref index, pageSize, count);
if (count > 0)
{
queryable = funOrderby(queryable);
if (index != 1)
{
queryable = queryable.Skip((index - 1) * pageSize);
}
queryable = queryable.Take(pageSize);
return(new PageInfo <TResult>(index, pageSize, count, selector(queryable)));
}
return(new PageInfo <TResult>(index, pageSize, count, new List <TResult>()));
}
