ListView fields not getting posted

I know I've done something like this before, but I have no idea why it isn't working now. I have a ListView with some textboxes. I want to read the text out of those boxes when I click a button (linkbutton, whatever).

        <asp:ListView runat="server" ID="lv_bar" EnableViewState="true">
            <LayoutTemplate>
                <table>
                    <tr>
                        <th>Foo</th>
                    </tr>
                    <tr runat="server" id="itemPlaceholder"></tr>
                </table>
            </LayoutTemplate>
            <ItemTemplate>
                <tr>
                    <td><asp:LinkButton ID="lb_delete" CausesValidation="false" runat="server" Text="Del" /></td>
                    <td><asp:TextBox id="txt_foo" runat="server" /></td>
                </tr>
            </ItemTemplate>
        </asp:ListView>
        <asp:LinkButton ID="lb_add" CausesValidation="false" runat="server" Text="Add" />

And then here's the relevant code-behind stuff:

protected void Page_Load(object sender, EventArgs e)
{
    lb_chapter_add.Click += lb_chapter_add_Click;

    if (!IsPostBack)
    {
            lv_chapters.DataSource = new List<Foo>() { new Foo() { Name = "harbl"} };
            lv_chapters.DataBind();
        }
    }

void lb_add_Click(object sender, EventArgs e)
{
    foreach (ListViewDataItem item in lv_bar.It开发者_如何学运维ems)
    {
        var txt_foo = (TextBox)item.FindControl("txt_foo");
        Response.Write("foo: " + txt_foo.Text);
    }
    Response.Write("<br />the end");
    Response.End();
}

But what I see when I enter some text into txt_foo and click lb_add is just "the end". What am I doing wrong here?

The problem it that you are using a a non persistent object as DataSource.

Due to clicking the button, you generate a postback and lv_chapters does not contain any items. Set a breakpoint in the line where the foreach is and you will see that lv_chapters.Items in null, or that it's Count property returns 0.