onLoad fires multiple times

Classic Servoy
1

Env :
Servoy Developer
Version R2 2.2.5-build 337
Java version 1.5.0_07-b03 (Windows XP)

This is what “ServoyDevUserGuide-2.2.3.pdf” says about ‘onLoad’:

The method that is triggered when a form is loaded from the
repository the FIRST TIME; used to alter elements, set globals,
hide toolbars, etc; onShow method can also be assigned.
NOTE: onShow should be used to access current foundset
dataproviders; onLoad cannot be used because the foundset data
is not loaded until after the form is loaded.

So, from that description…

if Form_A is loaded (and the user navigates some records etc) and then he swaps to another form, Form_B, (the user does some work)…then swaps back to Form_A. At this point, ‘onLoad’ should not be fired, correct ?

If so, why do we OCCASIONALLY see the method ‘onLoad’ fired again ?

‘onLoad’ is the ONLY form event on this form which we have configured to anything but DEFAULT.

mtia
julian

2

Servoy can keep forms in memory (a stack). Lets say 30.
So at one point form 1 can drop out of that stack when you load form 31.
When you access your first form again it has to load it. Hence the onLoad event gets fired.

3

Hi Robert :)

So, you’re telling me that you know the implementation of the form caching within Servoy. That’s good information to have :)

But, that doesn’t explain why the doc states what it does.
The doc is very clear in what it states.
Perhaps the doc should say what you’ve just explained ?

I wonder why they would use a java.util.Stack of size 30 for the Form instance management ? I wonder…

Oh…and if Forms did "drop off’…then it’s more likely to be q Queue instead of a Stack…I think !

Any ideas ??

J

4

Hi Julian,

No I don’t know the exact implementation of this cache function. But I’ve been told by people of Servoy that it keeps a stack of the most used/requested forms in memory. So eventually a lesser used form will drop out of this cache and when you request it again it will have to be loaded up again, thus firing the onLoad event.
I believe the amount of forms is memory related, not a hard form count.

5

Thanks for your help Robert :)

6

Uh oh… do I understand correctly that it is not possible to rely upon onLoad to only execute once per session?

Jim

7

I guess you can assume that. But let the people of Servoy confirm this.

By the way, if you want to be sure that a method is only called once I suggest you place it in Solution Settings under ‘On Open method’.
Or set a global variable that a method is already called…etc.

Hope this helps.

8

Thank you, Robert! Yes, very helpful.

May I suggest (Marc Norman) that the fact that OnLoad may be triggered multiple times is made clear in the documentation?

Jim