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Form creation using names in a table

Posted on 2000-04-23
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Last Modified: 2010-04-04
I have the names of the forms my application uses written in a field of a table. What I need to do is find the appropiate record (based on user actions) and showmodal the corresponding form using the name written in the field. How can I do this?

Thanks A LOT in advance for your help !!
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Question by:ajgonzalezm
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13 Comments
 
LVL 12

Expert Comment

by:rwilson032697
ID: 2742550
This should do it:

var
  TheFormClass : TPersistentClass;
  TheForm : TForm;

  TheFormClass := GetClass(TheTable.FieldByName('FormName').AsString);
  Application.CreateForm(TheFormClass, TheForm);
  TheForm.ShowModal;
  TheForm.Release;

Cheers,

Raymond.
0
 

Author Comment

by:ajgonzalezm
ID: 2749223
Hi, Raymond:

I didn't accept your answer just because I tried your suggestion on the computer and the compiler said: Incompatible types: ‘TComponentClass’ and ‘TPersistentClass’ on the line saying Application.CreateForm...

Could you please help me further?

THANK YOU !!!

AJ :-)
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LVL 12

Expert Comment

by:rwilson032697
ID: 2749422
You could use this line to create the form instead:

 TheForm := (TheFormClass as TForm).Create(Application);

Cheers,

Raymond.
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Author Comment

by:ajgonzalezm
ID: 2751163
Sorry... now I got an 'Operator not applicable to this operand type' on the assigment line you suggested...

Are you willing to help me further?

Thank you :-)

AJ
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LVL 12

Accepted Solution

by:
rwilson032697 earned 50 total points
ID: 2752995
Here's a working code sample :-)

type
  TFormClass = class of TForm;

procedure TForm1.Button1Click(Sender: TObject);
var
  TheClass : TPersistentClass;
  TheForm : TForm;
begin
  TheClass := GetClass('TFORM1');
  TheForm := TFormClass(TheClass).Create(Application);
  TheForm.ShowModal;
  TheForm.Release;
end;

Note that you need to register the classes you get GetClass to find, like this:

initialization
  registerclass(TForm1);

or

initialization
  registerclasses([TForm1, TForm2, ...]);


Cheers,

Raymond.

0
 

Author Comment

by:ajgonzalezm
ID: 2760781
THANKS A LOT RWilson !!! That was excellent !!!

I hope to become an expert like you in the near future...
by now I'm just a beginner.

Thanks again !!!

AJ
0
 
LVL 12

Expert Comment

by:rwilson032697
ID: 2761075
Glad I could help - sorry about the false starts :-)

Cheers,

Raymond.
0
 

Expert Comment

by:lfgmartins
ID: 11598356
Hi,
How can I do a  registerclass(TForm1), with a the name passed from a string var ('TForm1'). I need this to alllow dynamic form names. What else I'd have to do a registerclass([TUser, TContracts,...]) form my 50 forms.
0
 
LVL 12

Expert Comment

by:rwilson032697
ID: 11598501
Use the GetClass function to return the class name into a variable of type TClass and pass that to RegisterClass() as above.

Cheers,

Raymond.
0
 

Expert Comment

by:lfgmartins
ID: 11600695
unfortanelly don't work because the getclass() returns nil if the class is not registered. So I cannot apply RegisterClass next.
Thanks.
0
 
LVL 12

Expert Comment

by:rwilson032697
ID: 11607307
Where are the forms coming from then?
0
 

Expert Comment

by:lfgmartins
ID: 11607960
I've found a way I first need to registerclass in initialization of that form. Then when I getclass it don't give error :)
Thanks,
0
 
LVL 12

Expert Comment

by:rwilson032697
ID: 11608596
Great!

Cheers,

Raymond.
0

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