[RESOLVED] Detailsview null value

I want to check the value in Date Shipped. If there isn't anything in it, it won't allow the user to move on to the next page. I created a Session to check, but it never has a null value. I'm not sure why.

protected void Page_Load(object sender, EventArgs e)
    {
        lblError.Visible = false;
        ShippingError.Visible = false;
        CanceledError.Visible = false;
        dvAddress.Visible = false;
        dvCustomer.Visible = false;

    }
    protected void btnPacking_Click(object sender, EventArgs e)
    {
        Session["OrderID"] = dvOrder.SelectedValue;

        if (Session["OrderID"] != null)
        {
            if (Session["Shipped"] != null)
            {
                Response.Redirect("~/PackageManagement/Packing2.aspx");
            }
            else
            {
                ShippingError.Visible = true;
            }
        }

        else
        {
            lblError.Visible = true;
        }
    }

    protected void dvOrder_DataBound(object sender, EventArgs e)
    {


        if (dvOrder.SelectedValue != null)
        {
            Label AddressID = dvOrder.FindControl("lblAddressID") as Label;
            Address.Text = AddressID.Text;
            Session["Address1"] = AddressID.Text;

            if (dvOrder.CurrentMode == DetailsViewMode.ReadOnly)
            {
                Label Shipped = dvOrder.FindControl("lblShipped") as Label;
                Session["Shipped"] = Shipped.Text;

                
            }
            dvAddress.Visible = true;
            dvAddress.DataBind();
        }
        else
        {
            dvAddress.Visible = false;
        }

    }

Maybe you need to check for empty string instead. Or use the string isnullorempty().

Try as:

protected void btnPacking_Click(object sender, EventArgs e)
    {
        Session["OrderID"] = dvOrder.SelectedValue;

        if (!string.IsNullOrEmpty(Session["OrderID"] as string))
        {
            if (!string.IsNullOrEmpty(Session["Shipped"] as string))
            {
                Response.Redirect("~/PackageManagement/Packing2.aspx");
            }
            else
            {
                ShippingError.Visible = true;
            }
        }

        else
        {
            lblError.Visible = true;
        }
    }

Make sure each time databound you have to clear session values, for eg assign String.Empty in Session variable

 

Thank you! That worked (although I switched it to being empty).

Here's the code:

protected void Page_Load(object sender, EventArgs e)
    {
        lblError.Visible = false;
        ShippingError.Visible = false;
        CanceledError.Visible = false;
        dvAddress.Visible = false;
        dvCustomer.Visible = false;

    }
    protected void btnPacking_Click(object sender, EventArgs e)
    {
        Session["OrderID"] = dvOrder.SelectedValue;

        if (Session["OrderID"] != null)
        {
            if (string.IsNullOrEmpty(Session["Shipped"] as string))
            {
                ShippingError.Visible = false;
                Response.Redirect("~/PackageManagement/Packing2.aspx");
            }
            else
            {
                ShippingError.Visible = true;
            }
        }

        else
        {
            lblError.Visible = true;
        }
    }

    protected void dvOrder_DataBound(object sender, EventArgs e)
    {
        Session["Address1"] = null;
        Session["Shipped"] = null;

        if (dvOrder.SelectedValue != null)
        {
            Label AddressID = dvOrder.FindControl("lblAddressID") as Label;
            Address.Text = AddressID.Text;
            Session["Address1"] = AddressID.Text;

            if (dvOrder.CurrentMode == DetailsViewMode.ReadOnly)
            {
                Label Shipped = dvOrder.FindControl("lblShipped") as Label;

                if (Shipped != null)
                {
                    Session["Shipped"] = Shipped.Text;
                }
            }
            dvAddress.Visible = true;
            dvAddress.DataBind();
        }
        else
        {
            dvAddress.Visible = false;
        }

    }