如何知道在Datasnap REST服务上调用的方法

Question

On a Datasnap REST Service (ISAPI module) I would like to be able to know the method called. I'm going to use it on a generic routine to Write Logs on every Error/Exception that happens.

procedure WriteLog(Error: string);
var Log, Service, LogFile: string;
begin
  Service := ExtractFileName(GetModuleName(HInstance));
  Service := Copy(Service, 1, Service.Length - 4);
  if not TDirectory.Exists('C:\Logs') then TDirectory.CreateDirectory('C:\Logs');
  if not TDirectory.Exists('C:\Logs\' + Service) then TDirectory.CreateDirectory('C:\Logs\' + Service);
  LogFile := 'C:\Logs\' + Service + '\' + FormatDateTime('yyyy-mm-dd_hh-nn-zzz', Now) + '.txt';

  Log := 'Call : ' + XXXXXX + sLineBreak;
  Log := Log + 'User : ' + TDSSessionManager.GetThreadSession.GetData('User') + sLineBreak;
  Log := Log + 'IP : ' + TDSSessionManager.GetThreadSession.GetData('RemoteIP') + sLineBreak;
  Log := Log + 'Error : ' + sLineBreak + Error;
  TFile.WriteAllText(LogFile, Log);
end;

I need to substitute XXXXXX with the name of the method called.

This information is available on the WebModule of the service, at the Request param of the WebModuleBeforeDispatch event.

But I can't set that value in the Session Data (so it would be accessible for my WriteLog routine) because at that moment there is no session yet.

This code raises an AV:

procedure TWebModule1.WebModuleBeforeDispatch(Sender: TObject; Request: TWebRequest; Response: TWebResponse; var Handled: Boolean);
begin
  Response.SetCustomHeader('Access-Control-Allow-Origin','*'); 

  if Trim(Request.GetFieldByName('Access-Control-Request-Headers')) <> '' then begin
    Response.SetCustomHeader('Access-Control-Allow-Headers', Request.GetFieldByName('Access-Control-Request-Headers'));  
    Handled := True;  // I answer to CORS calls
  end;

  TDSSessionManager.GetThreadSession.PutData('MethodCalled', Request.PathInfo);

  if FServerFunctionInvokerAction <> nil then
    FServerFunctionInvokerAction.Enabled := AllowServerFunctionInvoker;
end;

At the moment I have set a threadvar variable on the WebModule to hold this value, so it can be accessible for the WriteLog routine.

It works but a global variable is a very ugly solution, and more importantly, it causes an small memory leak after every call.

Where do you think that I could save that value so I can read it when I need it ?.

Thank you.

Answer 1

我认为可以从DSAuthenticationManagerUserAuthorize事件中的EventObject.MethodAlias访问它。