Why VirtualDBTreeEx not cleared at form close?
lazarus / 31-LCL

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egsuh · 2025-03-27 09:36

I'm trying VirtualDBTreeEx, but it is not destroyed clearly. I don't
think I'm doing anything special. The attached image is the first
error message. What could possibly go wrong?

And how can I edit second, third, etc. columns? I can edit only the
first column.

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jamie · 2025-03-27 16:29

Don't you will get much response since there is so many variables in
the situation you left out.

 1. did you create that DB class at runtime?

 2. When closing a form there are many ways, one free's the form! did
you forget to free the class you may have created in the onCreate?

 3. Normally closing a for free's it, you need to do some cleanup of
any items you created at runtime.

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egsuh · 2025-03-28 02:36

Attached is my program.
Run it, and press "Refresh", which may take a few seconds. It
downloads dataset from my web server.
And then terminate the application. Then I see the error messages.

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egsuh · 2025-03-28 04:51

And how can I change the texts in columns, e.g. for TARGET or MAXN
fields? I tried to link DBEdits with the fields and changed the
values, but the changes were not reflected in VirtualDBTree.

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Zvoni · 2025-03-28 07:28

Quote from: egsuh on March 28, 2025, 03:36:02 amAttached is my
program.
Run it, and press "Refresh", which may take a few seconds. It
downloads dataset from my web server.
And then terminate the application. Then I see the error messages.
The only thing i see is in TForm1.
You create the Frame, but you don't free it.

Create an OnClose (or whichever event) for Form1 and free the Frame
explicitely there

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egsuh · 2025-03-28 09:20

It doesn't matter. I have assigned owner as self.

   frQuota := TfrQuota.Create(self);

and even when I destroyed at FormDestroy,

    frQuota.Free;

the problem does not disappear.

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wp · 2025-03-28 11:26

I am pretty sure that the bug is in the TVirtualDBTreeEx code itself:
the component create a FParentField, but never destroys it. I can
verify this in a simpler demo project which I am attaching (it
compiles with the version of the component from the author's site
(https://sourceforge.net/p/virtualdbtreeex/code/ci/default/tree/), I
don't know whether it compiles with the OPM version).

I contacted the author of the component (matthius).

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jamie · 2025-03-28 17:59

Quote from: wp on March 28, 2025, 12:26:24 pmI am pretty sure that the
bug is in the TVirtualDBTreeEx code itself: the component create a
FParentField, but never destroys it. I can verify this in a simpler
demo project which I am attaching (it compiles with the version of the
component from the author's site
(https://sourceforge.net/p/virtualdbtreeex/code/ci/default/tree/), I
don't know wither it compile with the OPM version).

I contacted the author of the component (matthius).

I had problems compiling your example, had to remove "Laz.Virtual...."
and use just the original Package, not the Laz one.

Also at that point I was able to get it to compile and run however,
exiting from the app to see the heap trace screen just hangs the
debugger and never exits.

So I don't know what to say.

 I am using 3.2 Laz and 3.2.2 Fpc

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wp · 2025-04-19 11:08

Quote from: wp on March 28, 2025, 12:26:24 pmI am pretty sure that the
bug is in the TVirtualDBTreeEx code itself: the component create a
FParentField, but never destroys it. [...]
I contacted the author of the component (matthius).
The current version of the component in OPM does not have the memory
leak any more.