Factory question

[bashan]

Hi,

I am trying to figure out a general concept of the @Factory patter.

I have a backing bean in which I have a method getVideo. Up until now this is what I was doing to implement getVideo method:

private Video video;

public Video getVideo()
{
  if (video == null)
  {
    video = myDAO.getVideoFromDB(getRequestParameter("vid")))
  }
  return video;
}

As ar as I understand by using Factory I can do:

@Factory
public Video getVideo()
{
  return myDAO.getVideoFromDB(getRequestParameter("vid")))}
}

Is it a correct usage of Factory?

Now, my question is: can I do: getVideo() in other methods and be sure that the code for fetching the Video object won't be done more than once?

Thanks,
Guy.

[sjmenden]

The two ways to use Factory are described here: http://docs.jboss.com/seam/2.0.3.CR1/reference/en-US/html_single/#d0e3905

You are using the first way.  As for directly accessing the method, sure, it is just a Java call, but if you directly access it it will be like any other Java call, called each time you make the call.  Try just doing #{video} which accesses it via the Factory.

[bashan]

So as far as I understand the Factroy pattern won't help me if I will be having to use the method getVideo() in my backing bean itself. for example, I want to do in my bean:

private List<Video> relatedVideos;

public List<Video> getRelatedVideos()
{
  if (relatedVideos == null)
  {
    relatedVideos = myDAO.getRelatedVideos(getVideo())
  }

  return relatedVideos;
}

Of course I can't access the video member directly since I am risking in null pointer exception...

Am I right? no neat solution to this issue in Seam?

Thanks,
Guy.