How to find an HTML Object in C# code behind

Question

I have a 3rd part control(it is a COM and it is not a server control).

 <object id="SigPlus1" classid="clsid:69A40DA3-4D42-11D0-86B0-0000C025864A" 
            name="SigPlus1" style="left: 0px; width: 544px; top: 0px; height: 86px">
    <param name="_Version" value="131095">
       <param name="_ExtentX" value="14393">
         <param name="_ExtentY" value="2275">
            <param name="_StockProps" value="9"></param>
         </param>
        </param>
    </param>
   </object>

In the C# code behind I use:

object o = (Page.FindControl("SigPlus1")

There is no error but o is set to null.

I know this object has a property named colormode, how can set this in the code behind

You don't have runat="server" on that tag, that means it's not a control and therefore FindControl isn't going to find it. — Matthew
– Matthew, Commented Apr 24, 2015 at 19:29
also your casting is off take a look at msdn Page.FindControl method — MethodMan
– MethodMan, Commented Apr 24, 2015 at 19:30

Rahul Tripathi · Accepted Answer · 2015-04-24 19:31:14Z

2

Try to add runat = "server"

<object id="SigPlus1" runat="server" classid="clsid:69A40DA3-4D42-11D0-86B0-0000C025864A" name="SigPlus1" style="left: 0px; width: 544px; top: 0px; height: 86px">

and if you dont want to add the runat = "server" then you can use like

var SigPlus1 = Request.Form["SigPlus1"];

answered Apr 24, 2015 at 19:31

Rahul Tripathi

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4 Comments

mason Over a year ago

var SigPlus1 = Request.Form["SigPlus1"]; would only get posted form values. It wouldn't get a control reference.

Rahul Tripathi Over a year ago

@mason:- Yes very correct! The the only option is to have runat = "server"

S Nash Over a year ago

I cannot run it as server i get an error. I include the error message as soon as i get to my computer

Robert Koernke Over a year ago

In order to change to using 'Runat=server': The above answer should have mentioned that all current page script references, if any exist, in your aspx page, need to be converted to this example format document.getElementByID('<%=SigPlus1.ClientID%>')

mason · Accepted Answer · 2015-05-01 16:55:15Z

1

Add the runat="server" attribute to the <object> element. Then you can find it in the code behind.

<object id="SigPlus1" runat="server" ...>

Code behind

var SigPlus1 = Page.FindControl("SigPlus1");

Or if the control is not in a templated control you can access it directly via it's ID without needing Page.FindControl().

edited May 1, 2015 at 16:55

answered Apr 24, 2015 at 19:30

mason

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3 Comments

S Nash Over a year ago

This tag, somehow does not let to add runat server. I asked the dev person why and he told me because this is a COM control(interop)

mason Over a year ago

@SNash what do you mean does not let you? Need details.

S Nash Over a year ago

Im on the bus but I post tge error messae as soo as i get home.

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