I am trying to open a form and close the form behind it in Delphi 10 [duplicate] - forms

Question

Application has a Login form and a Main form.
Applications DPR file has code to load Login form first, and when Login form returns successful login, then Main form is created and loaded.
When user logs out via a menu command in Main form, it should close the Main form and load the Login form.
Application exits only when user selects Exit in the Main form (or when user Cancels out of the Login form).
Using code in the application's DPR file, is it possible to code this?
Here is the code that presently exists:
program H;
uses
Forms,
SysUtils,
Registry,
MidasLib,
Dialogs,
Controls,
uDatamod in 'uDatamod.pas' {datamod: TDataModule} ,
uMain in 'uMain.pas' {fMain} ,
uMtlUpd in 'uMtlUpd.pas' {fMtlUpd} ,
uReportPrv in 'uReportPrv.pas' {fReportPrv} ,
uCamera in 'uCamera.pas' {fCamera} ,
uConfig in 'uConfig.pas' {fConfig} ,
uFuncs in 'uFuncs.pas',
uLogin in 'uLogin.pas' {fLogin} ,
uAdmin in 'uAdmin.pas' {fAdmin};
// MidasLib is required.
{$R *.res}
begin
Application.Initialize;
Application.MainFormOnTaskbar := True;
Application.Title := 'HTech';
if ((ParamCount = 1) and (UpperCase(ParamStr(1)) = '/CONFIG')) or
(getHServerHostName = EmptyStr) then
begin
Application.CreateForm(TfConfig, fConfig);
Application.Run;
end
else
begin
if not testHServerConnection then
begin
ShowMessage('Error: Could not connect to HServer');
Exit;
end;
Application.CreateForm(Tdatamod, Datamod);
while not TerminateApplicationFlag do
begin
fLogin := TfLogin.Create(Application);
try
if fLogin.ShowModal = mrOk then
begin
LoggedInEmployeeID := fLogin.FEmployeeID;
LoggedInEmployeeNm := fLogin.edtFirstName.Text + ' ' +
fLogin.edtLastName.Text;
AdminLogin := fLogin.FAdminUser;
FinanceLogin := fLogin.FFinanceUser;
end
else
begin
FreeAndNil(fLogin);
FreeAndNil(Datamod);
Exit;
end;
finally
// FreeAndNil(fLogin);
end;
if AdminLogin then
Application.CreateForm(TfAdmin, fAdmin)
else
begin
FreeAndNil(fLogin);
if not Assigned(fMain) then
Application.CreateForm(TfMain, fMain);
fMain.FHServerHost := getHServerHostName;
end;
Application.Run;
end;
end;
end.
The problem with the above code is that after one iteration (after user performs Logout in Main form), the application exits (control is returned to the operating system) because " fLogin.ShowModal " exits without showing the Login form.
Here is the code from the Main form:
Procedure LogoutProcedure;
begin
TerminateApplicationFlag := False;
Close;
end;
Procedure ExitProcedure;
begin
TerminateApplicationFlag := True;
Close;
end;
I'm stuck with this and would appreciate any advice or corrections in getting it to work.
Thank you in advance.
Regards,
Steve Faleiro

Answer 1

Maybe this very simple solution is sufficient:
The project file:
program Project1;
uses
Forms,
FMain in 'FMain.pas' {MainForm},
FLogin in 'FLogin.pas' {LoginForm};
{$R *.res}
var
MainForm: TMainForm;
begin
Application.Initialize;
Application.CreateForm(TMainForm, MainForm);
Login;
Application.Run;
end.
The main form:
unit FMain;
interface
uses
Classes, Controls, Forms, StdCtrls, FLogin;
type
TMainForm = class(TForm)
LogoutButton: TButton;
procedure LogoutButtonClick(Sender: TObject);
end;
implementation
{$R *.dfm}
procedure TMainForm.LogoutButtonClick(Sender: TObject);
begin
Login;
end;
end.
And the login form:
unit FLogin;
interface
uses
Classes, Controls, Forms, StdCtrls;
type
TLoginForm = class(TForm)
LoginButton: TButton;
CancelButton: TButton;
procedure FormCreate(Sender: TObject);
end;
procedure Login;
implementation
{$R *.dfm}
procedure Login;
begin
with TLoginForm.Create(nil) do
try
Application.MainForm.Hide;
if ShowModal = mrOK then
Application.MainForm.Show
else
Application.Terminate;
finally
Free;
end;
end;
procedure TLoginForm.FormCreate(Sender: TObject);
begin
LoginButton.ModalResult := mrOK;
CancelButton.ModalResult := mrCancel;
end;
end.
Now, this answer works here, quite well with Delphi 7, but I suspect problems with more recent versions were Application.MainFormOnTaskbar and Application.ShowMainForm are True by default. When so, try to set them to False.