Delphi - Why is my global variable "inacessible" when i debug
- by Antoine Lpy
I'm building an application that contains around 30 Forms.
I need to manage sessions, so I would like to have a global LoggedInUser variable accessible from all forms.
I read "David Heffernan"'s post about global variables, and how to avoid them but I thought it would be easier to have a global User variable rather than 30 forms having their own User variable.
So i have a unit : GlobalVars
unit GlobalVars;
interface
uses User; // I defined my TUser class in a unit called User
var
LoggedInUser: TUser;
implementation
initialization
LoggedInUser:= TUser.Create;
finalization
LoggedInUser.Free;
end.
Then in my LoginForm's LoginBtnClick procedure I do :
unit FormLogin;
interface
uses
[...],User;
type
TForm1 = class(TForm)
[...]
procedure LoginBtnClick(Sender: TObject);
private
{ Déclarations privées }
public
end;
var
Form1: TForm1;
AureliusConnection : IDBConnection;
implementation
{$R *.fmx}
uses [...]GlobalVars;
procedure TForm1.LoginBtnClick(Sender: TObject);
var
Manager : TObjectManager;
MyCriteria: TCriteria<TUser>;
u : TUser;
begin
Manager := TObjectManageR.Create(AureliusConnection);
MyCriteria :=Manager.Find<TUtilisateur>
.Add(TExpression.Eq('login',LoginEdit.Text))
.Add(TExpression.Eq('password',PasswordEdit.Text));
u := MyCriteria.UniqueResult;
if u = nil then
MessageDlg('Login ou mot de passe incorrect',TMsgDlgType.mtError,[TMsgDlgBtn.mbOK],0)
else begin
LoggedInUser:=u; //Here I assign my local User data to my global User variable
Form1.Destroy;
A00Form.visible:=true;
end;
Manager.Free;
end;
Then in another form I would like to access this LoggedInUser object in the Menu1BtnClick procedure :
Unit C01_Deviations;
interface
uses
System.SysUtils, System.Types, System.UITypes, System.Classes, System.Variants,
FMX.Types, FMX.Graphics, FMX.Controls, FMX.Forms, FMX.Dialogs, FMX.StdCtrls,
FMX.ListView.Types, FMX.ListView, FMX.Objects, FMX.Layouts, FMX.Edit, FMX.Ani;
type
TC01Form = class(TForm)
[...]
Menu1Btn: TButton;
[...]
procedure Menu1BtnClick(Sender: TObject);
private
{ Déclarations privées }
public
{ Déclarations publiques }
end;
var
C01Form: TC01Form;
implementation
uses [...]User,GlobalVars;
{$R *.fmx}
procedure TC01Form.Menu1BtnClick(Sender: TObject);
var
Assoc : TUtilisateur_FonctionManagement;
ValidationOK : Boolean;
util : TUser;
begin
ValidationOK := False;
util := GlobalVars.LoggedInUser; // Here i created a local user variable for debug purposes as I thought it would permit me to see the user data. But i get "Inaccessible Value" as its value
util.Nom:='test';
for Assoc in util.FonctionManagement do // Here is were my initial " access violation" error occurs
begin
if Assoc.FonctionManagement.Libelle = 'Reponsable équipe HACCP' then
begin
ValidationOK := True;
break;
end;
end;
[...]
end;
When I debug I see "Inaccessible Value" in the value column of my user. Do you have any idea why ?
I tried to put an integer in this GlobalVar unit, and i was able to set its value from my login form and read it from my other form..
I guess I could store the user's id, which is an integer, and then retrieve the user from the database using its id. But it seems really unefficient.
