会话变量-数据表空值-asp.net C#

Question

我似乎无法确定为什么我的会话变量在打印项单击事件中返回 null。数据表出现在会话变量之前。

感谢任何建议。

    protected void btnGetOrderData_Click(object sender, EventArgs e)
    {
        Class1 x = new Class1(); // create a new instance of class1

        x.sopnumbe = txtOrder.Text; // pass the class string the value of text box order 

        DataSet ds = x.GetOrderData(); // call get order from class1 "x" instance 

        DataTable orderDataTable = ds.Tables[0]; // dataset to datatable (first)

        Session["sess_dt"] = orderDataTable; // create a session var to store dataset and use elsewhere


        //  GridView1.DataSource = ds;
        //  GridView1.DataBind();

    }

    protected void btnPrintItem_Click(object sender, EventArgs e)
    {

        DataTable dt = (DataTable)Session["sess_dt"];

Answer 1

存储：

 DataTable dt = new DataTable();
 Session["sess_dt"] = orderDataTable; 

检索：

 DataTable dt = (DataTable)Session["sess_dt"];

检查您的orderDataTable 是否有值。