linq to sql 扩展方法

1、DataContext扩展方法

/// <summary>
/// DataContext扩展方法
/// </summary>
public static class DataContextExtends
{
/// <summary>
/// ExecuteQuery方法扩展，将对象以redader方式转换为实体
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="dataContext"></param>
/// <param name="query"></param>
/// <returns></returns>
public static List<T> ExecuteQuery<T>(this DataContext dataContext, IQueryable<object> query)
{
return ExecuteQuery<T>(dataContext, query, 1, query.Cast<T>().Count());
}

/// <summary>
/// ExecuteQuery方法扩展，代表分页的
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="dataContext"></param>
/// <param name="query"></param>
/// <param name="pageIndex"></param>
/// <param name="pageSize"></param>
/// <returns></returns>
public static List<T> ExecuteQuery<T>(this DataContext dataContext, IQueryable<object> query, int pageIndex, int pageSize)
{
int total = query.Count();
int totalPages = total / pageSize;

if (total % pageSize > 0)
totalPages++;

if (pageIndex > totalPages)
{
pageIndex = totalPages;
}
if (pageIndex < 1)
{
pageIndex = 1;
}
query.Skip((pageIndex - 1) * pageSize).Take(pageSize).ToList();
DbCommand command = dataContext.GetCommand(query);
dataContext.OpenConnection();
using (DbDataReader reader = command.ExecuteReader())
{
return dataContext.Translate<T>(reader).ToList();
}
}
private static void OpenConnection(this DataContext dataContext)
{
if (dataContext.Connection.State == ConnectionState.Closed)
dataContext.Connection.Open();
}

}