Need help with canceling a routine

[robplatt]

I have a sub that connects to a remote database to download records, could be 10 could be 10,000. I have a progress bar that shows the progress on which record its on, with a text to display a number 5/239. I have a "me.refresh" to keep the lable updating between records.

 

I have a cancel button on the form that when pressed, should set blnCancel to True. While my other sub is looping through the records, if it sees blnCancel = True then it should " throw new exception("Aborted") ". Maybe theres a better way then how im approaching this.

 

However. my problem lies in clicking the button. I can't click it. my app is too busy to listen for the click event. What should I do?

[Cags]

Adding Application.DoEvents() to the loop should allow the UI to still be used.

[mskeel]

It sounds like you need to seperate the DB call out into a worker thread. The BackgroundWorker for .Net 2.0 is an easy way to do that. The catch is that you'll need to put a check in your method that downloads the records to keep an eye out for a cancel so that it knows when to terminate the thread (you can only politely request a background worker thread terminate.)

 

Check this thread out for an example: http://www.xtremedotnettalk.com/showthread.php?t=96990&highlight=backgroundworker

[robplatt]

Thanks mskeel. I'm already using a few threads in my app with success. My only concern is being able to update the UI while the background worker is running. I'm found a difficult way to get around that in another area of my app, which can't apply to this scenerio. I will try the application.doevents. it sounds like it will work.

[robplatt]

wow. application.doevents works great. its even allowing my controls to update faster then the me.refresh does. SWEET. thanks!

[mskeel]

Ahh....I get what you are saying. I was thinking frozen UI which is not the case. Glad to see you got if figured out.