public DbSet <T> OrderBy <S>(OrderOpt opt, Expression <Func <T, S> > exp)
{
List <string> lstName = new List <string>();
var colmem = exp.Body as MemberExpression;
if (colmem != null)
{
lstName.Add(colmem.Member.Name);
}
else
{
var colmem2 = exp.Body as NewExpression;
if (colmem2 != null)
{
lstName.AddRange(colmem2.Members.Select(x => x.Name));
}
}
if (lstName.Count < 1)
{
throw new ArgumentException("不支持的表达式");
}
return(this);
}
public static string ToSql(this OrderOpt opt)
{
switch (opt)
{
case OrderOpt.ASC:
return(" ASC");
case OrderOpt.DESC:
return(" DESC");
default:
throw new ArgumentException("未知的排序修饰符");
}
}
public OrderByNode(Column col, OrderOpt opt)
{
this.col = col;
this.opt = opt;
}