麻烦的FindControl和动态地创建的控件 [英] Trouble with FindControl and dynamicly created controls

问题描述

举例code：

    var div = new HtmlGenericControl("div");
    div.Controls.Add(new Literal() { ID = "litSomeLit" });
    var lit = (Literal)div.FindControl("litSomeLit");
    Assert.IsNotNull(lit);

这code不能断言，因为点亮为空。调试表明，div.Controls肯定包含的ID文字litSomeLit。我的问题是为什么？和有没有办法让一个特定ID的控制，而在同一时间一个元素做递归搜索div.Controls []的手？

This code fails the assert, because lit is null. Debugging shows that div.Controls definitely contains a literal with ID of "litSomeLit." My questions are "Why?" and "Is there any way to get a control of a specific ID without doing a recursive search of div.Controls[] by hand one element at a time?"

我正在做的事情这种方式的原因是，我的实际应用是不那么straightforward-方法我写给出用在许多可能的配置几个子控件一个复杂的控制。我需要访问特定的控制几层下来（例如，ID为txtSpecificControl控制可能会在 StartingControl.Controls [0] .Controls [2] .Controls [1] .Controls [3] ）。通常情况下我可以做的FindControl（txtSpecificControl），但这似乎并没有在刚刚动态创建的控件（如上面的例子中code）工作

The reason I'm doing things this way is that my actual application is not so straightforward- a method I'm writing is given a complex control with several subcontrols in a number of possible configurations. I need to access a specific control several layers down (eg, the control with ID "txtSpecificControl" might be at StartingControl.Controls[0].Controls[2].Controls[1].Controls[3]). Normally I could just do FindControl("txtSpecificControl"), but that does not seem to work when the controls were just dynamically created (as in the above example code).

推荐答案

近，我可以告诉，有没有办法做什么，我试图完成无添加控件的页面。如果我猜，我想说的FindControl使用该控件，它通常包含的所有控件的上方当前的ID（如OuterControlID $ LowerControlId $的TargetControlID）的UniqueID属性。当控制实际上被添加到网页，将只得到生成的。

Near as I can tell, there is no way to do what I'm trying to accomplish without adding the control to the page. If I had to guess, I'd say that FindControl uses the UniqueID property of the control, which generally contains the IDs of all the controls above the current one (eg OuterControlID$LowerControlId$TargetControlID). That would only get generated when the control actually gets added to the page.

总之，这里的递归深度优先搜索的实现的FindControl当控件没有连接到页面然而这会工作：

Anyway, here's an implementation of recursive depth-first-search FindControl that'll work when the control is not attached to the page yet:

    public static Control FindControl(Control parent, string id)
    {
        foreach (Control control in parent.Controls)
        {
            if (control.ID == id)
            {
                return control;
            }
            var childResult = FindControl(control, id);
            if (childResult != null)
            {
                return childResult;
            }
        }
        return null;
    }

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