在ASP.NET中访问代码隐藏中的用户控件

Question

This question is for an ASP.NET guru. Its driving me nuts.

I have inherited an ASP.NET Web Forms application. This application uses a complex structure of nested user controls. While complex, it does seem necessary in this case. Regardless, I have a page that uses a single UserControl. We will call this UserControl root control. This UserControl is defined as follows:

widget.ascx

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="widget.ascx.cs" Inherits="resources_userControls_widget" %>
<div>
  <asp:Panel ID="bodyPanel" runat="server" />
</div>

widget.ascx.cs

public partial class resources_userControls_widget : System.Web.UI.UserControl
{
    private string source = string.Empty;
    public string Source
    {
        get { return source; }
        set { source = value; }
    }

    private string parameter1 = string.Empty;
    public string Parameter1
    {
        get { return parameter1; }
        set { parameter1 = value; }
    }

    private DataTable records = new DataTable();
    public DataTable Records
    {
        get { return records; }
        set { records = value; }
    }

    protected override void OnPreRender(EventArgs e)
    {
        base.OnPreRender(e);
        UserControl userControl = LoadControl(source) as UserControl;
        if (parameter1.Length > 0)
            userControl.Attributes.Add("parameter1", parameter1);
        bodyPanel.Controls.Add(userControl);
    }

    private void InsertUserControl(string filename)
    {
    }
}

In my application, I am using widget.ascx in the following way: page.aspx

<uc:Widget ID="myWidget" runat="server"  Source="/userControls/widgets/info.ascx" />

page.aspx.cs

protected void Page_Load(object sender, EventArgs e)
{
  DataTable table = GetData();
  myWidget.Records = table;
}

Please notice how info.ascx is set as the UserControl we want to load in this case. This approach is necessary in this case. I've removed the extraneous code that justifies it to focus on the problem. Regardless, in info.ascx.cs I have the following:

info.ascx.cs

protected void Page_Load(object sender, EventArgs e)
{
  // Here's the problem
  // this.Parent.Parent is a widget.ascx instance.
  // However, I cannot access the Widget class. I want to be able to do this
  // Widget widget = (Widget)(this.Parent.Parent);
  // DataTable table = widget.Records;
}

I really need to get the value of the "Records" property from the Parent user control. Unfortunately, I can't seem to access the Widget class from my code-behind. Are there some rules about UserControl visibility at compile time that I'm not aware of? How do I access the Widget class from the code-behind of info.ascx.cs?

Thank you!

Answer 1

Firstly you need to create an interface and implement it to the Widget user control class.

For instance,

public interface IRecord
{
    DataTable Records {get;set;}
} 

public partial class resources_userControls_widget : System.Web.UI.UserControl, IRecord
{
 ...
}

And in code behind of Info.ascx.cs,

protected void Page_Load(object sender, EventArgs e)
{
  // Here's the problem
  // this.Parent.Parent is a widget.ascx instance.
  // However, I cannot access the Widget class. I want to be able to do this
  // Widget widget = (Widget)(this.Parent.Parent);
  // DataTable table = widget.Records;

  IRecord record=this.Parent.Parent;
  DataTable table = widget.Records;
}

Answer 2

In your case, maybe better to use some server object's like ViewState or Session. Fill it within DataTable on your page and get it in Page_load event handler on info.ascx user control.