Frames in MSHTML

[David Pendrey]

Hello all,

I am using the WebBrowser control to browse a webpage containing frames and am having difficulties accessing the 'frames' property of a document object. Bellow is my code and the error recieved:
webAccess.Navig ate(URL);

// Wait until document is loaded. This part DOES work

IHTMLDocument2 mDoc = (IHTMLDocument2 )(webAccess.Doc ument);

IHTMLFramesColl ection2 mFrames = (IHTMLFramesCol lection2)(mDoc. frames);

The final line of code returns the error of:

An unhandled exception of type 'System.Invalid CastException' occurred in xxxx.exe

Additional information: No such interface supported

Does anyone out there know of a way to fix this? It would be greatly apreciated.

[Chris Priede]

Hi,

David Pendrey wrote:

I am using the WebBrowser control to browse a webpage containing
frames and am having difficulties accessing the 'frames' property of
a document object. An unhandled exception of type 'System.Invalid CastException'
occurred in xxxx.exe Does anyone out there know of a way to fix this? It would be greatly
apreciated.

Here's an excerpt of actual working code I wrote a while ago, which drills
down to the document contained in a frame named "main", and does things with
its contents. Hopefully that will help you:

mshtml.HTMLDocu ment doc = (mshtml.HTMLDoc ument)browser.D ocument;
mshtml.FramesCo llection frames = (mshtml.FramesC ollection)doc.f rames;
mshtml.IHTMLWin dow2 mainFrame = null;
for (int i = 0; i < frames.length; i++)
{
object refIndex = i;
mshtml.IHTMLWin dow2 frame = (mshtml.IHTMLWi ndow2)frames.it em(ref
refIndex);
if (frame.name == "main")
mainFrame = frame;
}
if (mainFrame != null)
{
mshtml.IHTMLDoc ument2 mainFrameDoc = mainFrame.docum ent;
[...]
}

As I recall, I too encountered numerous invalid cast errors while trying to
interpret and folow the sparse documentation on this topic. I ended up
writing code to dump the actual type of all objects in the tree and referred
to that.
--
Chris Priede

[David Pendrey]

Hi,

Thanks, that code is working better but still not well enough unfortunatly. I've fiddled around a bit and your code works fine when it's in the code being pressed by a button after you press a button to load the page. However if you have code to go to a page, then sleep until ReadyState == SHDocVw.tagREAD YSTATE.READYSTA TE_COMPLETE and then use your code it doesn't work. I tried to wait a while (up to 5 seconds) and running your code in a seperate thread with no luck. Any ideas on this?

David Pendrey

"Chris Priede" <pr****@panix.c om> wrote in message news:en******** ******@TK2MSFTN GP12.phx.gbl...

Hi,

David Pendrey wrote:

I am using the WebBrowser control to browse a webpage containing
frames and am having difficulties accessing the 'frames' property of
a document object.

An unhandled exception of type 'System.Invalid CastException'
occurred in xxxx.exe

Does anyone out there know of a way to fix this? It would be greatly
apreciated.

Here's an excerpt of actual working code I wrote a while ago, which drills
down to the document contained in a frame named "main", and does things with
its contents. Hopefully that will help you:

mshtml.HTMLDocu ment doc = (mshtml.HTMLDoc ument)browser.D ocument;
mshtml.FramesCo llection frames = (mshtml.FramesC ollection)doc.f rames;
mshtml.IHTMLWin dow2 mainFrame = null;
for (int i = 0; i < frames.length; i++)
{
object refIndex = i;
mshtml.IHTMLWin dow2 frame = (mshtml.IHTMLWi ndow2)frames.it em(ref
refIndex);
if (frame.name == "main")
mainFrame = frame;
}
if (mainFrame != null)
{
mshtml.IHTMLDoc ument2 mainFrameDoc = mainFrame.docum ent;
[...]
}

As I recall, I too encountered numerous invalid cast errors while trying to
interpret and folow the sparse documentation on this topic. I ended up
writing code to dump the actual type of all objects in the tree and referred
to that.


--
Chris Priede

[Chris Priede]

David Pendrey wrote:

Thanks, that code is working better but still not well enough
unfortunatly. I've fiddled around a bit and your code works fine when
it's in the code being pressed by a button after you press a button
to load the page. However if you have code to go to a page, then
sleep until ReadyState == SHDocVw.tagREAD YSTATE.READYSTA TE_COMPLETE
and then use your code it doesn't work. I tried to wait a while (up
to 5 seconds) and running your code in a seperate thread with no
luck. Any ideas on this?

My project was an automated sequence of about half a dozen steps, which logs
in to a site with a username/password, navigates to a specific page, submits
a search form on that page, and scrubs data from the results. The sequence
is driven by a timer and a state machine. Completion, timeout and errors
are detected through DocumentComplet e and NavigateError events. This might
not be the greatest design, but it seems to work well enough under both
normal and error circumstances.

I never attempted to use ReadyState to detect completion. This is not to
say it wouldn't work, though.

If you use a separate thread, make sure you are using Invoke/BeginInvoke for
anything having to do with the browser control. It also appears necessary
to do so within any handlers for the browser control's events.
--
Chris Priede

[David Pendrey]

Thank you for the assistance. I was running my code from invisde a seperate
thread from the main application so that the window would be automatically
redrawn and this appears to have been causing the problems. Now I run it all
in the same thread and simply use the following function to load a page and
wait until it is fully loaded:

protected HTMLDocument GotoPage(string URL)

{

while (webAccess.Read yState != SHDocVw.tagREAD YSTATE.READYSTA TE_COMPLETE)

{

System.Windows. Forms.Applicati on.DoEvents();

System.Threadin g.Thread.Sleep( 250);

}

webAccess.Navig ate(URL);

while (webAccess.Read yState != SHDocVw.tagREAD YSTATE.READYSTA TE_COMPLETE)

{

System.Windows. Forms.Applicati on.DoEvents();

System.Threadin g.Thread.Sleep( 250);

}

return (HTMLDocument)( webAccess.Docum ent);

}
Thank you again for all of your help :)
"Chris Priede" <pr****@panix.c om> wrote in message
news:%2******** *******@TK2MSFT NGP15.phx.gbl.. .

David Pendrey wrote:

Thanks, that code is working better but still not well enough
unfortunatly. I've fiddled around a bit and your code works fine when
it's in the code being pressed by a button after you press a button
to load the page. However if you have code to go to a page, then
sleep until ReadyState == SHDocVw.tagREAD YSTATE.READYSTA TE_COMPLETE
and then use your code it doesn't work. I tried to wait a while (up
to 5 seconds) and running your code in a seperate thread with no
luck. Any ideas on this?

My project was an automated sequence of about half a dozen steps, which
logs in to a site with a username/password, navigates to a specific page,
submits a search form on that page, and scrubs data from the results. The
sequence is driven by a timer and a state machine. Completion, timeout
and errors are detected through DocumentComplet e and NavigateError events.
This might not be the greatest design, but it seems to work well enough
under both normal and error circumstances.

I never attempted to use ReadyState to detect completion. This is not to
say it wouldn't work, though.

If you use a separate thread, make sure you are using Invoke/BeginInvoke
for anything having to do with the browser control. It also appears
necessary to do so within any handlers for the browser control's events.
--
Chris Priede