Skip Inno Setup custom page, unless specific radio button is selected on previous page

I have code which is used for custom installation using Inno Setup. In this I have two radio buttons on a custom page. If user selects the first radio button, it should show another custom page with user input text box and text to be save in file. If user select the other radio button, the other custom page should not show.

Here is my code

[Code]
var
  FullRadioButton: TNewRadioButton;
  PartRadioButton: TNewRadioButton;
  CustomPage: TWizardPage;
  UserInputsPage: TInputQueryWizardPage;
  FullDescLabel: TLabel;
  PartDescLabel: TLabel;
  url: String;

const
  FullDescText ='Full Installation.';
  PartDescText ='Partial Installation.';

procedure InitializeWizard; 
begin
  CustomPage := CreateCustomPage(wpWelcome, 'Installation type', '');
  FullRadioButton := TNewRadioButton.Create(WizardForm);
  FullRadioButton.Parent := CustomPage.Surface;
  FullRadioButton.Top := 16;
  FullRadioButton.Width := CustomPage.SurfaceWidth;
  FullRadioButton.Font.Style := [fsBold];
  FullRadioButton.Font.Size := 9;
  FullRadioButton.Caption := 'Default Installation'
  FullDescLabel := TLabel.Create(WizardForm);
  FullDescLabel.Parent := CustomPage.Surface;
  FullRadioButton.Checked := True;
  FullDescLabel.Left := 8;
  FullDescLabel.Top := FullRadioButton.Top + FullRadioButton.Height + 8;
  FullDescLabel.Width := CustomPage.SurfaceWidth; 
  FullDescLabel.Height := 40;
  FullDescLabel.AutoSize := False;
  FullDescLabel.Wordwrap := True;
  FullDescLabel.Caption := FullDescText;
  PartRadioButton := TNewRadioButton.Create(WizardForm);
  PartRadioButton.Parent := CustomPage.Surface;
  //PartRadioButton.Checked := True
  PartRadioButton.Top := FullDescLabel.Top + FullDescLabel.Height + 16;
  PartRadioButton.Width := CustomPage.SurfaceWidth;
  PartRadioButton.Font.Style := [fsBold];
  PartRadioButton.Font.Size := 9;
  PartRadioButton.Caption := 'Custom Installation'
  PartDescLabel := TLabel.Create(WizardForm);
  PartDescLabel.Parent := CustomPage.Surface;
  PartDescLabel.Left := 8;
  PartDescLabel.Top := PartRadioButton.Top + PartRadioButton.Height + 8;
  PartDescLabel.Width := CustomPage.SurfaceWidth;
  PartDescLabel.Height := 40;
  PartDescLabel.AutoSize := False;
  PartDescLabel.Wordwrap := True;
  PartDescLabel.Caption := PartDescText;
end;

function NextButtonClick(CurPageID: Integer): Boolean;
begin
if (PartRadioButton.Checked) then
    UserInputsPage := CreateInputQueryPage(wpWelcome,
          'Url information', 'Url',
          'Please specify the following informat, then click Next.');
    
    UserInputsPage.Add('URL:', False);
    UserInputsPage.Values[0] := ExpandConstant('');
  if(CurPageID = UserInputsPage.ID) then;
  begin
    url := UserInputsPage.Values[0];
    SaveStringToFile('path', 'user_input='+'"'+url+'"'+#13#10,True);
  end;
 Result := True;
end;

Please help me out
Thanks in advance!

Solution

Use TWizardPage.OnShouldSkipPage event (or ShouldSkipPage event function) to conditionally skip your custom page.

The custom page should better also be created (unconditionally) in the InitializeWizard, not in the NextButtonClick (the NextButtonClick can be called multiple times for the same page, if the user returns back).

Additionally, the UserInputsPage must show after the CustomPage. While you are currently constructing it to show before. For that, pass CustomPage.ID as the first argument of the CreateInputQueryPage.

function UserInputsPageShouldSkipPage(Sender: TWizardPage): Boolean;
begin
  Result := not PartRadioButton.Checked;
end;

UserInputsPage :=
  CreateInputQueryPage(
    CustomPage.ID, 'Url information', 'Url',
    'Please specify the following informat, then click Next.');
// ...
UserInputsPage.OnShouldSkipPage := @UserInputsPageShouldSkipPage;