级联下拉列表值时出错 [英] Error with cascading dropdownlist value

问题描述

嗨

我的级联下拉列表出现错误，因为下面的代码在此行旁边给出了此错误消息：



cmd.Parameters.AddWithValue（@ BizSubCateg，SubCatBizDDL.SelectedItem.Value）;



，错误信息为：未设置对象引用一个对象的实例。



注意：如果用户没有选择和值，这个下拉列表应该不存储任何内容，所以它应该工作但是我不知道为什么我会遇到这个错误信息

Hi
I am facing an error with my cascading dropdownlist as the below code its gives me this error message next to this line:

cmd.Parameters.AddWithValue("@BizSubCateg", SubCatBizDDL.SelectedItem.Value);

and the error message is:" Object reference not set to an instance of an object. "

Note: this dropdown list should store nothing in case if the users didnt select and value so it should work but i dont know why i am facing this error message

protected void btnSave_Click(object sender, EventArgs e)
        {

            HttpCookie cookie = Request.Cookies.Get("Location");
            string Location = string.Empty;
            SqlConnection cn = new SqlConnection(sc);
            SqlCommand cmd = new SqlCommand();
            Location = cookie.Value;

            
            string sqlstatment = @"INSERT INTO UserInfo (UID, FN, LN, Password, RePass, Email,Country, State,City, Post, Img, Logo,RegDate,Address, UsrType,BizCateg,BizSubCateg) VALUES
                (@UID,@FN,@LN,@Password,@RePass,@Email,@Country,@State,@City,@Post,@Img,@Logo,@RegDate,@Address,@UsrType,@BizCateg,@BizSubCateg)";

            cmd.Connection = cn;
            cmd.CommandType = CommandType.Text;
            cmd.CommandText = sqlstatment;

            //Insert the parameters first
            cmd.Parameters.AddWithValue("@UID", UsrNme.Text);
            cmd.Parameters.AddWithValue("@FN", fnbox.Text);
            cmd.Parameters.AddWithValue("@LN", lnamebox.Text);
            cmd.Parameters.AddWithValue("@Password", passtxtbx1.Text);
            cmd.Parameters.AddWithValue("@RePass", passtxtbx2.Text);
            cmd.Parameters.AddWithValue("@Email", emailbox.Text);
            cmd.Parameters.AddWithValue("@Country", cookie.Value);
            cmd.Parameters.AddWithValue("@State", statedrdolst.SelectedItem.Text);
            cmd.Parameters.AddWithValue("@City", citiesdrdolst.SelectedItem.Text);
            cmd.Parameters.AddWithValue("@Post", postbox.Text);
            cmd.Parameters.AddWithValue("@Img", persimgFileUpload1.FileName);
            cmd.Parameters.AddWithValue("@Logo", logoFileUpload.FileName);
            cmd.Parameters.AddWithValue("@Address", regaddrstxtbx.Text);
            cmd.Parameters.AddWithValue("@UsrType", UsrTypeDrDo.SelectedItem.Text);
            cmd.Parameters.AddWithValue("@BizCateg", BizCateDDL.SelectedItem.Value);
            cmd.Parameters.AddWithValue("@BizSubCateg", SubCatBizDDL.SelectedItem.Value);
            
            
            //Get the Current Date Time here
            cmd.Parameters.AddWithValue("@RegDate", DateTime.Now);



            if (!string.IsNullOrEmpty(UsrNme.Text))
            {
                Lblcheckusername.Text = "User Name Already Exist";
                Lblcheckusername.ForeColor = System.Drawing.Color.Red;
            }
            else
            {
                Lblcheckusername.Text = "User Name Available";
                Lblcheckusername.ForeColor = System.Drawing.Color.Green;
            }

            if (persimgFileUpload1.HasFile)
            {

                persimgFileUpload1.SaveAs(Server.MapPath("~/images/users/" + persimgFileUpload1.FileName));

            }



            if (logoFileUpload.HasFile)
            {

                logoFileUpload.SaveAs(Server.MapPath("~/images/Logos/" + logoFileUpload.FileName));

            }


            SqlDataAdapter ad = new SqlDataAdapter(cmd);
            DataSet ds = new DataSet();
            ad.SelectCommand = cmd;
            ad.Fill(ds);
            Session["UsrNme"] = UsrNme.Text;
            Response.Redirect("User panel.aspx");


        }

推荐答案

检查所选项目是否合适，然后决定你要去的价值基于此插入，例如：

check the item selected or not and then decide the value you going to insert based on that, for example:

if(SubCatBizDDL.SelectedIndex < 0)
	cmd.Parameters.AddWithValue("@BizSubCateg", DBNull.Value);
else
	cmd.Parameters.AddWithValue("@BizSubCateg", SubCatBizDDL.SelectedItem.Value);

check ..

check..

String Str=SubCatBizDDL.SelectedValue;

str获取什么值...数据然后将其转换为@BizSubCateg数据类型..



或尝试..

what value str getting..ifhas data then convert it to @BizSubCateg datatype..

or try..

if(BizCateDDL.SelectedItem.Value!="" && SubCatBizDDL.SelectedValu!="")
{
   cmd.Parameters.AddWithValue("@BizSubCateg", DBNull.Value);
}
else
{
  cmd.Parameters.AddWithValue("@BizSubCateg", SubCatBizDDL.SelectedItem.Value);
}

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