Collin tree list view and data from mysql - Are There limits on row numbers?

i have another question about this Thread:

is there a limit of rows that can go in the listview?

because if i search for example the word "Birra"
crasches without errors

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spesa_1.aia (102.4 KB)

In order to avoid that you can load data as user scrolls using scroll handler

Carlo, non credo dipenda da limiti, a me funziona soltanto se scrivo * nella textbox

Not seeing any issues in retrieving the data from the server. However,

You appear to have an infinite loop somewhere in your "elaborarisposta" procedure (or one of the procedures within it). This is causing a memory overload and crashing your app.


because i cannot debug!
cant find issues with blocks!

Do you have any idea how i can debig this??

The strange is that if the query has few elements in the answer all is fine

Noticed that if the User taps "Home" on Screen 3, the App opens a new Screen1, but it doesn't close Screen 3. Therefore, next time Screen 2 Button 1 is tapped, an additional Screen 3 is created.

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In Procedure "elaboransposta", you are calling two other procedures in succession. Best not to do this because of the way App Inventor works - the 2nd Procedure could be run before the first has finished.

So, Procedure "splittiamo" should run Procedure "populatelistview" as the last line of the Procedure (or they could be combined into one).

Procedure "splittamo" does not verify the length of list "dasplittare " before attempting to select items from it.

Do you mean something like this?

Yes :sunglasses: But test the length of list first:


Most importantly, avoid having multiple Screen 3s.

how i can close screen3?

when i click on button i can close screen or open another screen!

how to do both things?

i edited with your suggestions but app crashes always when search for example "birra"

spesa_1_test.aia (102.7 KB)

Close Screen 3 using the same method you use to close Screen 2.

Multiple Screen 3's will cause the App to crash, but that is not necessarily the cause of the Colin Tree List View Crash. 315 rows is not many. The App Inventor List View accepts approx 1800 rows.

In your new file "expense_1_test" , Screen 2, "shoplist" initialisation fails because it can't pre-build, it has to be built after the Screen has initialised as the initialise Block receives the start value used by "shoplist".

So like this:


Should test list length here also, like this:

I can't test your App here because I do not know what I am supposed to enter on Screen 1 :koala:

try for example word "birra" that crash app

or word "moretti" or "panna" that works fine and listview is ok

OK, all three words work fine here (with all corrections in place). :grin:

Had I been writing this App, I would have chosen to use Virtual Screens. It would be faster and safer because all screens share the same memory allocation and there is no need to pass data between screens therefore.

I'm away from my PC now. Here is a description of Virtual Screens:

When we define virtual screens, we use one 'real' App Inventor Screen (most often Screen1). Screen-sized Vertical Arrangements on it are displayed/hidden as required - they are the Virtual Screens. This is generally a better approach for multi-screen Apps, they share data without having to "pass" it between screens and it also reduces code duplication, making the App more efficient and the code easier to follow if you have to return to it at a later date.
So, instead of separate "houses", virtual screens are "rooms" of the same "house".

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