Question

I have a web user control (OrderDefinition.ascx) which has a dropdownlist (ddl_CustomerCode), which is populated by web user control’s page_load function

    public void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {

            ddl_CustomerCode.DataSource = OrderDefinitionData.GetCustomers();
            ddl_CustomerCode.DataTextField = "CustomerCode";
            ddl_CustomerCode.DataValueField = "CustomerName";                
            ddl_CustomerCode.DataBind();
         }
    }

In my default.aspx page I dynmically add this web user control

    Control x = LoadControl("Controls/OrderDefinition.ascx");
    Panel1.Controls.Add(x);

I want to pass parameter to this web user control from my default.aspx, and I come up with the idea of using a session or viewstate or cache to use. So now my default.aspx looks like

    Session["myParam"] = "customerNo1";
    Control x = LoadControl("Controls/OrderDefinition.ascx");
    Panel1.Controls.Add(x);

And my Page_Load will look like

    public void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            string myParam = Session["myParam"];
            ddl_CustomerCode.DataSource = OrderDefinitionData.GetCustomers(myParam);
            ddl_CustomerCode.DataTextField = "CustomerCode";
            ddl_CustomerCode.DataValueField = "CustomerName";                
            ddl_CustomerCode.DataBind();
         }
    }

The problem is I am not sure about the way I code above, Should I trust this architecture? Please clarify me if this is the correct way to pass a parameter to a web user control.

Answer 1

As other have suggested you can do this in your ascx:

    public string myParam { get; set; }
    public void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            ddl_CustomerCode.DataSource = OrderDefinitionData.GetCustomers(myParam);
            ddl_CustomerCode.DataTextField = "CustomerCode";
            ddl_CustomerCode.DataValueField = "CustomerName";                
            ddl_CustomerCode.DataBind();
         }
    }

Then do this in your ASPX:

WebControl1 x = (WebControl1)Page.LoadControl("Controls/OrderDefinition.ascx");
x.myParam = "customerNo1";
Panel1.Controls.Add(x);

Note the casting to your TYPE of web control when you instantiate your web control through the LoadControl function – its important to do this cast so that your properties and methods are accessible to you.