Zugg Software :: View topic - [2.20] Button Label not updated to blank when value is null.

Posted: Thu Mar 20, 2008 1:53 pm

I have a button who's label is %item(@somearray, 1). When there is an item at position 1 in the array everything is fine. If I make the list a %null the %item is now returning a %null value which should change the button text to "" (%null). When I set the array to %null, the old value that was in the array doesn't get removed from the label text. I'm still looking at the old value even after I empty the array. It stays stuck at the old value until I populate the array with a non-null value.

Posted: Fri Mar 21, 2008 5:13 pm

Added to bug list.

Wizard Joined: 11 Jul 2002 Posts: 1265 Location: USA

ReedN you WERE talking about a "string list" an not a real array right?

I'm gonna call this fixed for 2.24. If I'm wrong please speak up.

Posted: Thu May 08, 2008 6:02 am

In my case it was indeed a "string list". It's still here in 2.24:

Procedure:

Posted: Thu May 08, 2008 6:13 am

Try doing

#var stringvar ""

instead of using %null. At least that worked for me. Using {} also worked. Let me know if those work for you or not so that I can see if it's a problem with %null or something else in your settings.

Posted: Thu May 08, 2008 1:08 pm

Fixed the procedure. You need to have other text in there as well. So just having the button be '%item(@stringvar, 1)' won't do it, but having the button text be '1) %item(@stringvar, 1)' shows the issue.

Procedure:

Posted: Thu May 08, 2008 1:13 pm

Confirmed, using #var stringvar "" and #var stringvar {} has exactly the same effect.

Posted: Thu May 08, 2008 5:17 pm

OK, found it. The problem was that setting a database variable to null wasn't causing the internal event to fire to indicate a changed variable. So button captions would not update, nor would status bar items or expression triggers.

The problem, once again, was the hash table cache. CMUD avoids converting the hash table into a string value whenever possible. So using #ADDITEM was adding a value to the hash table, but the internal string value of the variable is still null. So setting the variable back to null didn't look like the variable was changing. Anything that is done to cause the hash table to be converted to a string, like doing a #SHOW @stringvar would fix this. But since the button only used the %item function, which is optimized to use the hash table and doesn't need the full string value, the full string value was never computed.

Anyway, this is fixed now. CMUD checks to see when the hash table is being changed and flags that so that CMUD will later trigger the "variable is changing" event internally.

Posted: Thu May 08, 2008 6:38 pm

Are you still releasing as 2.24 by overwriting or are you doing a 2.25?

Posted: Thu May 08, 2008 6:42 pm

Too many fixes to overwrite 2.24, so it will be 2.25 :(

Posted: Sun May 11, 2008 11:52 pm

This is very strange. When the variable is cleared from the command prompt the button updates properly. But if you put the code to set it to %null in an alias/#oninput it doesn't work.

Posted: Tue May 13, 2008 7:34 am

Confirming that this is fixed in 2.25.

Posted: Tue May 13, 2008 1:06 pm

Posted: Tue May 13, 2008 3:20 pm

Taz is correct. The procedure I posted is fixed, but the issue still remains if it cannot be done from a trigger/alias.

Posted: Wed May 21, 2008 11:40 pm

Can anyone else confirm whether you can do this from an alias/trigger?

Posted: Thu May 22, 2008 10:34 am

I just confirmed that it does change when using an alias or trigger. Are you unable to do so using both?

Posted: Fri May 23, 2008 2:33 am

Only updates properly for me when I execute the change through the command line. So it appears we see the same exact thing. This is probably just an oversight on Zugg's part when he made the change.

Posted: Fri May 23, 2008 11:33 pm

I said DOES not doesn't so we're not seeing the same behaviour.

Posted: Fri May 23, 2008 11:57 pm

Oh whoops, misread.

Posted: Tue Jun 03, 2008 12:33 am

This is odd. Observed the following:

In my current session:

- Works in everything except for an oninput trigger I have, which is where I saw this issue originally. This is always why it appeared unfixed to me.

In a new session:

- It works all the time.

So I'm guessing this is some issue with oninput triggers and I'll need to do a bit more work to isolate this.

Wizard Joined: 25 Mar 2003 Posts: 1113 Location: USA

I have similar issues with my status bar items not updating when I null out a variable that's being used on the status bar. Not sure if the two things are related or not.

Posted: Tue Jun 03, 2008 1:56 pm

There have already been various cases of cached values not being handled right in Cmud, and I expect this to be another one of these when I finally get to its root.

Posted: Tue Jun 03, 2008 2:02 pm

Zugg: Before I kill myself trying to figure out what's causing this. Is there any reason a variable assigned %null in an oninput trigger would differ from one being assigned the same thing through the command prompt?

I can actually print out the value that I've assigned null and it is indeed null, but will not change in the button text until something else modifies the variable. Seems a classic case of the cache not updating, but I'm not sure why it only occurs sometimes.

Posted: Tue Jun 03, 2008 4:45 pm

Nope, there shouldn't be any difference doing it in an oninput trigger or doing it on the command line.

Posted: Wed Jun 04, 2008 12:32 am

I took my settings and imported them to a new session. I then proceeded to slim it down until only the code necessary to demonstrate was left.

Procedure: