从父页面从Web用户控件中的元素获取值

Question

I have a Web User Control that contains a CheckBoxList.

MyListControl:

<asp:checkboxlist id="chkList" runat="server">
     <asp:listitem id="option1" runat="server" value="Madrid" />
     <asp:listitem id="option2" runat="server" value="Oslo" />
     <asp:listitem id="option3" runat="server" value="Lisbon" />
</asp:checkboxlist>

I want to check what Items are checked before a form is submitted on the parent page. I was hoping it would work like this:

myParentPage:

MyUserControlInstance.chkList.Items.Count

How does one reference a control in a user control from the parent page?

Answer 1

Encapsulate the property in your code behind of the control..

public int GetLength
{
    get
    {
        return CheckListBox.Items.Cast<ListItem>().Where(
                                     i => i.Selected).ToList().Count;
    }
}

---

Now replace the line

MyUserControlInstance.chkList.Items.Count

with MyUserControlInstance.GetLength

---

Note - Please add necessary Namespaces like System.Collections.Generic and System.Linq

Answer 2

I would expose this information as a public property on the User Control, returning only the necessary information, such as:

using System.Collections.Generic;
using System.Linq;

// ...

public IList<string> CheckedValues
{
    get { return chkList.Items.Cast<ListItem>().Where(i => i.Selected).Select(i => i.Value).ToList(); }
}