Access elements by Custom Attribute

Question

I am wondering if I am able to access Html elements in aspx from code behind by custom attribute name. Like

HtmlElement[] allElements = Page.FindElementByCustomName("custom-name");

and it will give me an array of all elements with that attribute suppose my aspx is as below

<a runat="server" custom-name = "any">Faf</a>
<a runat="server">AB</a>
<a runat="server" custom-name = "any">Amla</a>

and allElements will have two a elements i.e

<a runat="server" custom-name = "any">Faf</a>
<a runat="server" custom-name = "any">Amla</a>

Is it possible?

Answer 1

You can iterate through all controls in a page, but it will have to be done recursively. For example, start with Page.Controls, then, for each control, iterate through its Controls collection. For a control to take attributes it needs to implement IAttributeAccessor; you can check if the control in your iteration implements this interface. It is an interface that is required when you are to insert custom attributes on markup. For example, WebControl implements it. If now, when you try to add a custom attribute, ASP.NET will fail saying that there is no property with that name. Something like:

public static void ListControls(ControlCollection controls, List<Control> controlsFound)
{
    foreach (var control in controls.OfType<Control>())
    {
        if (control is IAttributeAccessor)
        {
            controlsFound.Add(control);
            ListControls(control.Controls, controlsFound);
        }
    }
}

Which you should call from your page:

var controlsFound = new List<Control>();
ListControls(this.Controls, controlsFound);

In the end, just iterate through controlsFound, which you know is a collection of IAttributeAccessor and retrieve attribute attribute-name:

var attr = (control as IAttributeAccessor).GetAttribute("attribute-name");