遍历asp.net页上的所有控件

Question

I'm using ascx and I need to iterate through all of the controls and selects each that have cssClass attribute set to 'required'.

I have the following code:

foreach (Control masterControl in Page.Controls)
        {
            if (masterControl is MasterPage)
            {
                foreach (Control formControl in masterControl.Controls)
                {
                    if (formControl is System.Web.UI.HtmlControls.HtmlForm)
                    {
                        foreach (Control contentControl in formControl.Controls)
                        {
                            if (contentControl is ContentPlaceHolder)
                            {
                                foreach (Control childControl in contentControl.Controls)
                                {

                                }
                            }
                        }
                    }
                }
            }
        }

however.. i cannot access childControl.CssClass. How do I access it?

Thanks in advance!

Answer 1

CssClass property is a member of the WebControl class .

You have to check if the control is a webcontrol, or, if it's only a control, you can get the attribute "class" in the attributes collection.

for example, you can do :

List<WebControl> wcs = new List<WebControl>();
GetControlList<WebControl>(Page.Controls, wcs)
foreach (WebControl childControl in wcs)
{
     if(childControl.CssClass == "required") {
          // process the control
     }
}

You also have to iterate recursively. Code found here : Using C# to recursively get a collection of controls from a controlcollection :

private void GetControlList<T>(ControlCollection controlCollection, List<T> resultCollection)
where T : Control
{
    foreach (Control control in controlCollection)
    {
        //if (control.GetType() == typeof(T))
        if (control is T) // This is cleaner
            resultCollection.Add((T)control);

        if (control.HasControls())
            GetControlList(control.Controls, resultCollection);
    }
}

Answer 2

The Control class doesn't have that CssClass property, the WebControl does. So try to cast your childControl to WebControl. If that worked, then you can access the CssClass property.

WebControl webCtrl = childControl as WebControl;
if (webCtrl != null)
{
   webCtrl.CssClass = "test";
}

Answer 3

Regarding your comment on the answer above, you need to first check that it is a WebControl and then cast it to a WebControl

var webControl = childControl as WebControl;

if(webControl != null)
{
   if(webControl.CssClass == 'required')
   // Do your stuff
}