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Werner · Guest

I'm trying to use
1. edit field in IWDBGrid
2. using a checkbox in IWDBGrid.

So far I could post a checkBox with the code bollow.
It works perfect, but when doing a lot of action, the posts are getting
SLOWER and SLOWER.
It seems that with every click, the onRendering start over, and thus
creating more CheckBoxes ??

1. Do I need to free and nil the checkbox at some place ?
2. Is the code below safe to use? and what is best to use TIWDBCheckBox or
IWCheckBox
3. How to use this technique to edit a field, because the edit has no
onclick event?

Any idee is welcom

procedure TIWForm1.UpdateFieldClick(ASender: TObject);
begin
//UserSession.Table1.RecNo:=(ASender as TIWCheckBox).Tag;
UserSession.Table1.RecNo:=(ASender as TIWDBCheckBox).Tag;
if UserSession.table1.state <> dsEdit then UserSession.Table1.Edit;
UserSession.Table1.FieldByName('Updated').AsBoolean:=not
UserSession.Table1.FieldByName('Updated').AsBoolean;
UserSession.Table1.post;
end;

procedure TIWForm1.IWDBGrid1RenderCell(ACell: TIWGridCell; const ARow,
AColumn: Integer);
var dbCB:TIWDBCheckBox;
//cb :TIWCheckBox;
begin

(* using the TIWDBCheckBox *)
if (AColumn = 4) and (ARow>0) then begin
dbCB := TIWDBCheckBox.Create(Self); //
must this be freeed somewhere??
dbCB.DataField ='Updated';
dbCB.DataSource:=UserSession.DataSource1;
dbCB.Tag :=UserSession.Table1.RecNo;
dbCB.OnClick :=UpdateFieldClick;
dbCB.Caption :='';
ACell.Text :='';
ACell.Control := dbCB;
end;

(* using the TIWCheckBox
if (AColumn = 4) and (ARow>0) then begin
CB:= TIWCheckBox.Create(self);
CB.checked :=UserSession.Table1.FieldByName('Updated').AsBoolean;
CB.Tag :=UserSession.Table1.RecNo;
CB.OnClick :=UpdateFieldClick;
CB.Caption :='';
ACell.text :='';
ACell.Control :=CB;
end;
*)
end;

Farshad · Guest

You shouldn't create objects in OnRender event. It fills your form with lots
of CheckBoxes after a few run. Not to mention the resource leak that occurs
each time you create a new CheckBox without freeing previous ones. You must
create a static set of checkboxes in OnCreate event and free them in
OnDestroy event. If you want to create them in OnRender event dynimacally
then you must keep track of what you've created and free them when OnDestroy
is triggered. However you must be aware NOT to create same object in same
cell twice or more.

Delphi do not do garbage collection. The general rule is that you must Free
everything you Create programatically.

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Werner · Guest

Do I need to create as many checkboxes versus records in the OnCreate?,
wouldn't that be an overhead, or is there an other way.
Don't know where to start, could you give me an example please?

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Ricardo · Guest

Hello Werner,

There is also an other way. I do not create components at runtime. Instead i
use the onmRenderCell of the IWGrid. For the cell which need a
RadioButton/Checkbox i set the ACell.RawText := True; Then i put in the
ACell.Text some html, like;

IF (AColumn = 0) Then Begin
ACell.RawText := True;
ACell.Text := '<input type=radio name="sel" value="%d" onclick="return
SubmitClickConfirm(''btnRadioHandler'', ''%d'', true, '''');">';
End;

Instead of using the SubmitClickConfirm you can also use with some
javascript and put the selected values into hiddenfields. I hope this give
you some direction.

Ricardo

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Werner · Guest

Ok, I tried this code bellow, and it works much faster now,
BUT when freeing the checkboxes I got an error at component 31, but there
are 59 components ?? Cannot figure out what's wrong
Still wondering when having lot of records, creating a checkbox for everone
is the right approch?
Any comments or get a shorter/better way I would appriciate it

procedure TIWForm1.IWAppFormCreate(Sender: TObject);
var CB:TIWCheckBox;
begin
UserSession.Table1.First;
while not UserSession.Table1.eof do begin
CB := TIWCheckBox.Create(self);
CB.Name :='CB'+IntToStr(UserSession.Table1.RecNo);
CB.Tag :=UserSession.Table1.RecNo;
CB.OnClick :=UpdateFieldClick;
CB.Caption :='';
UserSession.Table1.next;
end;
end;

procedure TIWForm1.IWAppFormDestroy(Sender: TObject);
var i:integer;
begin
for i := 0 to ComponentCount -1 do
if Components[i] is TIWCheckBox then TIWCheckBox(Components[i]).Free;
// got a error ListIndex out of bounds (31) at the 31st Component ??
// ComponentsCounts = 59, Total checkBoxes = 55
end;

procedure TIWForm1.UpdateFieldClick(ASender: TObject);
begin
UserSession.Table1.RecNo:=(ASender as TIWCheckBox).Tag;
if UserSession.table1.state <> dsEdit then UserSession.Table1.Edit;
UserSession.Table1.FieldByName('Updated').AsBoolean:=not
UserSession.Table1.FieldByName('Updated').AsBoolean;
UserSession.Table1.post;
end;

procedure TIWForm1.IWDBGrid1RenderCell(ACell: TIWGridCell; const ARow,
AColumn: Integer);
var CB:TIWCheckBox;
begin
if (AColumn = 4) and (ARow>0) then begin
CB:=
TIWCheckBox(FindComponent('CB'+IntToStr(UserSession.Table1.RecNo)));
if CB<>nil then begin
CB.checked :=UserSession.Table1.FieldByName('Updated').AsBoolean;
ACell.Control:=CB;
ACell.text :='';
end;
end;
end;

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Werner · Guest

Dear Ricardo,

It looks a great approch, but cannot get it done. I'm very new about the
javascript and html.
I get the checkbox in the grid, but nothing works so far.
Don't know how to assign the %d var and get the value in the table.
Could you give more info how to do this?
Werner

procedure TIWForm1.IWDBGrid1RenderCell(ACell: TIWGridCell; const ARow,
AColumn: Integer);
var CB:TIWCheckBox;
begin
if (AColumn = 4) and (ARow>0) then begin
ACell.RawText:=True;
ACell.Text :=
'<input type=checkbox name="sel" value="%d" onclick="return
SubmitClickConfirm(''checkboxHandler'', ''%d'', true, '''');">';
end;
end;

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Loren Szendre · Guest

Werner,

It looks like your loop through ComponentCount changes the
ComponentCount whilst it executes. I think you can get away with that
kind of code if you start from the end and work toward the beginning:

for i := ComponentCount-1 downto 0 do
// your thing

or you might need to store the ComponentCount in a variable to use in
your for loop.

Loren

Werner · Guest

Thank you Loren, you're absolutely right. So logical... Freeing works
perfect now.
Werner

procedure TIWForm1.IWAppFormDestroy(Sender: TObject);
var i:integer;
begin
{ free checkboxes from end to begin! }
for i := ComponentCount-1 downto 0 do
if Components[i] is TIWCheckBox then TIWCheckBox(Components[i]).Free;
end;

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