GridView Sort (排序)

GridView本身有一个Sort()函数：public virtual void Sort (
    string sortExpression,    SortDirection sortDirection)使用上相当方便。

但在实际使用中，常用的是点击每一列的标题来排序，点击标题会触发：protected void GridView_Sorting(object sender, GridViewSortEventArgs e)事件。从GridViewSortEventArgs中可以拿到SortDirection和SortExpression。但是GridView.Sort()本身也会触发GridView_Sorting()，如果在GridView_Sorting()中调用GridView.Sort()会无限的循环，直到堆栈溢出。

这样就只能使用DataView.Sort属性来排序，再Bind到GridView上。

示例：protected string m_sortDirection
{
  get
  {
    if (ViewState["m_SortDirection"] == null)
  {
    return String.Empty;
  }
  return (string)ViewState["m_SortDirection"];
  }
    set { ViewState["m_SortDirection"] = value; }
}

protected string m_sortExpression
{
  get { return (string)ViewState["m_SortExpression"]; }
  set { ViewState["m_SortExpression"] = value; }
}

protected void bindData(string sortExpression, string sortDirection)
{
  DataView dv = new DataView(ds.Tables[0]);
  dv.Sort = sortExpression;
  if (sortDirection != String.Empty)
  {
    dv.Sort += " " + sortDirection;
 }

  gvRequisition.DataSource = dv;
  gvRequisition.DataBind();
}

protected void GridView_Sorting(object sender, GridViewSortEventArgs e)
{
  m_sortExpression = e.SortExpression;
  if (m_sortDirection == "ASC")
  {
    m_sortDirection = "DESC";
  }

  else if (m_sortDirection == "DESC")
  {
    m_sortDirection = "ASC";
  }
  bindData(m_sortExpression, m_sortDirection);
}