[SOLVED] TCustomComboBox to TComboBox Invalid type cast
'RunError(219)'
lazarus / 16-Databases

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patyit · 2020-08-07 11:52

Hi !

Below is a code issue that works perfectly on FPC 3.0.5 but indicates
an error at runtime on FPC 3.2.0. Runtime Error: 'RunError (219)',
Type Cast error.
I looked through the change list between FPC 3.0 and 3.2, but couldn’t
figure out what had changed.

If anyone could tell me what was wrong, I would be very grateful !

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TForm1.DBGrid1SelectEditor(Sender: TObject; Column: TColumn;  var
Editor: TWinControl);begin  if Column.Visible and not Column.ReadOnly
then begin    if Column.Field = QStatNstat then begin      with Editor
as TCustomComboBox do begin        Style := csDropDown;       
Items.CommaText := FDataMod.GetParam('status');        DropDownCount
:= 15;        AutoComplete  := True;       
TComboBox(Editor).OnEditingDone := @DBCBDone;  // <-- Type Cast error
between TCustomComboBox and TComboBox      end;    end; 
end;end; procedure TForm1.DBCBDone(Sender: TObject);begin  if
QStat.State in dsEditModes then    QStat.Post;  EBar.Clear; 
EBar.SetFocus;end;

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Handoko · 2020-08-07 11:59

I tested these code below on Lazarus 2.0.10 GTK2 Linux FPC 3.2.0, did
not get any compile-time error:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i unit
Unit1; {$mode objfpc}{$H+} interface uses  Classes, SysUtils, Forms,
Controls, StdCtrls, DBGrids; type   { TForm1 }   TForm1 =
class(TForm)    ComboBox1: TComboBox;    DBGrid1: TDBGrid;   
procedure DBGrid1SelectEditor(Sender: TObject; Column: TColumn;     
var Editor: TWinControl);  private    procedure DBCBDone(Sender:
TObject);  end; var  Form1: TForm1; implementation {$R *.lfm} { TForm1
} procedure TForm1.DBCBDone(Sender: TObject);begin  //end; procedure
TForm1.DBGrid1SelectEditor(Sender: TObject; Column: TColumn;  var
Editor: TWinControl);begin  TComboBox(Editor).OnEditingDone :=
@DBCBDone;end; end.
Try to compile the simplified code above, do you still get the error?
FYI, you need to put a DBGrid and a ComboBox on the form.

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Blaazen · 2020-08-07 12:08

Why do you retype twice?
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i       with
Editor as TCustomComboBox do begin        ...       
Editor.OnEditingDone := @DBCBDone;  // should be enough      end;

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patyit · 2020-08-07 12:16

Handoko :

The problem is not compiling time, running time is the problem.
I am using Lazarus 2.0.11 GTK2 Linux FPC 3.2.1, FPCUP Fixex 64Bit
version.

Blaazen:

The Editor does not have the OnEditingDone property because it is
TCustumComboBox.

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Handoko · 2020-08-07 12:21

Sorry, I didn't read your post carefully. I thought type casting error
is a compile time issue.

Can you provide a demo so we can test it? Runtime error is harder to
fix, it will be easier if we can have the runable source code to test.
If you're not willing to publicize the source code you can write a
simplified demo that showing the problem.

Create a new folder, copy and paste all the necessary files except:
the binary (exe file), *.bak, lib and backup folders. Compress the
folder and send the zip here.

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wp · 2020-08-07 12:34

The OnSelectEditor event in a grid is normally used to tell the grid
that the default editor, a TEdit-like editor, should be replaced by
the component passed to the "Editor" parameter -- that's why it is a
"var" argument.

You do not assign anything to "Editor", i.e. Editor remains what was
selected by the grid. And this certainly is not a TCombobox.

You seem to need a picklist editor. Therefore you should assign Editor
to the result of "EditorByStyle(cbsPickList)" which selects a built-in
combobox (TPicklistCellEditor = class(TCustomCombobox -- see
grids.pas):

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TForm1.DBGrid1SelectEditor(Sender: TObject; Column: TColumn;  var
Editor: TWinControl);begin  if Column.Visible and not Column.ReadOnly
then begin    if Column.Field = QStatNstat then begin      Editor :=
EditorByStyle(cbsPickList);      with Editor as TPickListCellEditor do
begin        Style := csDropDown;        Items.CommaText :=
FDataMod.GetParam('status');        DropDownCount := 15;       
AutoComplete  := True;       
TPickListCellEditor(Editor).OnEditingDone := @DBCBDone;        end;  
end;  end;end;

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Blaazen · 2020-08-07 12:57

@ The Editor does not have the OnEditingDone property because it is
TCustumComboBox.
Sorry, it is even simplier:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i       with
Editor as TCustomComboBox do begin          ...        OnEditingDone
:= @DBCBDone;  // should be enough      end;
But your code yet miss two important things: assign Editor itself
(parameter by reference) and bound rectangle.
Code should be like this:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i Editor :=
DBCB;  with Editor as TCustomComboBox do begin   
BoundsRect:=DBGrid1.CellRect(aCol, aRow);    Style := csDropDown;   
Items.CommaText := FDataMod.GetParam('status');    DropDownCount :=
15;    AutoComplete  := True;    OnEditingDone := @DBCBDone;   
Visible:=True;  //*  end;  
*You should also manage visibility. Usually, grid-cell editor is
invisible and become visible only on demand.

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patyit · 2020-08-07 13:46

Thanks to everyone for the help, the problem is solved !

@wp pointed out the TPickListCellEditor should be used instead of
TCustumComboBox.
I have attached a small test project that demonstrates the correct
code (at least which works correctly for this case).

Yours sincerely.

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Handoko · 2020-08-07 14:06

Thank you for providing the problem-solved demo, so others can learn
from the code.