Advanced HTTP Router Handler Examples

Beyond simple procedure callbacks, the HTTP router supports sophisticated handler patterns for complex applications. These examples demonstrate method events, interface handlers, and object class handlers.

// Method Event Handler Example
type
  TAPIHandler = class
  private
    FVersion: String;
  public
    constructor Create(const AVersion: String);
    procedure HandleVersionInfo(ARequest: TRequest; AResponse: TResponse);
  end;

constructor TAPIHandler.Create(const AVersion: String);
begin
  inherited Create;
  FVersion := AVersion;
end;

procedure TAPIHandler.HandleVersionInfo(ARequest: TRequest; AResponse: TResponse);
begin
  AResponse.Content := Format('{"version": "%s"}', [FVersion]);
  AResponse.ContentType := 'application/json';
end;

// Interface Handler Example
type
  IUserService = interface(IRouteInterface)
    ['{12345678-1234-1234-1234-123456789012}']
  end;

  TUserService = class(TInterfacedObject, IUserService)
  public
    procedure HandleRequest(ARequest: TRequest; AResponse: TResponse);
  end;

procedure TUserService.HandleRequest(ARequest: TRequest; AResponse: TResponse);
begin
  AResponse.Content := 'User service response';
end;

// Object Class Handler Example
type
  TRequestProcessor = class(TRouteObject)
  public
    procedure HandleRequest(ARequest: TRequest; AResponse: TResponse); override;
  end;

procedure TRequestProcessor.HandleRequest(ARequest: TRequest; AResponse: TResponse);
begin
  AResponse.Content := 'Processed by object instance';
end;

// Registration examples:
var
  APIHandler: TAPIHandler;
  UserService: IUserService;
begin
  APIHandler := TAPIHandler.Create('1.0');
  UserService := TUserService.Create;

  // Register method event
  HTTPRouter.RegisterRoute('/version', rmGet, @APIHandler.HandleVersionInfo);

  // Register interface handler
  HTTPRouter.RegisterRoute('/users', rmGet, UserService);

  // Register object class handler
  HTTPRouter.RegisterRoute('/process', rmPost, TRequestProcessor);
end.

These examples simply demonstrate the core functionality of the HTTP router. An actual implementation would typically integrate with an HTTP server framework like fpweb or fphttp to handle incoming requests, and would use one of the various request-handling units such as httpapp or cgiapp.