Hello list!
I would like to define a class, Tklasje, of my own which contains a
database in the private section. Using this class I want to access the
database. (another Lazarus-application could succesfully show this
database, so I assume the database is OK).
The class is defined in unit2 and used in unit1 (see below). When
running this little program I see the TEdit change to "gecreeerd" but
then I get an error message: "acces violation". This doesn't change when
I change the DoeIets procedure of the Tklasje class into something
different like:
procedure Tklasje.DoeIets;
begin
d_database.First;
end;
What do I do wrong? Can anyone help me find a solution?
With kind regards,
Paul van der Vlis.
----------------------------------------------
unit unit2;
{$mode objfpc}{$H+}
interface
uses
Classes, SysUtils, sqlite3ds, DbCtrls, sqldb, db;
type
Tklasje = class
private
d_database : TSqlite3Dataset;
public
constructor Create;
destructor Destroy; override;
procedure DoeIets;
end;
implementation
constructor Tklasje.Create;
begin
d_database := TSqlite3Dataset.Create(nil);
try
with d_database do
begin
if Active then Close;
FileName := 'sqlite3filenaam';
TableName := 'tabelnaam';
Open;
end;
except
d_database.Free;
d_database := nil;
end;
end;
destructor Tklasje.Destroy;
begin
d_database.Free;
d_database := nil;
Inherited;
end;
procedure Tklasje.DoeIets;
begin
d_database.Active := true;
end;
initialization
end.
----------------------------------------------
unit unit1;
{$mode objfpc}{$H+}
interface
uses
Classes, SysUtils, LResources, Forms, unit2, StdCtrls;
type
{ TSchermpje }
TSchermpje = class(TForm)
status: TEdit;
procedure statusClick(Sender: TObject);
private
{ private declarations }
public
{ public declarations }
end;
var
MijnSchermpje: TSchermpje;
implementation
procedure TSchermpje.statusClick(Sender: TObject);
var
MijnKlasje : TKlasje;
begin
status.Text := 'creeren';
MijnKlasje.Create;
status.Text := 'gecreeerd';
MijnKlasje.DoeIets;
status.Text := 'gedaan';
MijnKlasje.Destroy;
status.Text := 'klaar';
end;
initialization
{$I unit1.lrs}
end.
----------------------------------------------
Met vriendelijke groet,
Paul van der Vlis.
--
http://www.vandervlis.nl/
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