Rails 3- Handling a conditional Create in a Controller

Hello,

I have the following in my def create controller:

@photo = current_user.photos.create(params[:photo].merge(:project_id
=> params[:project_id])

In my app photo records are valid if they have a project_id or not....

But I need my create statement not to error and work for both cases.
CASE A. If there is a param project_id, insert it
CASE B. If not, insert the default NULL value when creating the record

What's the smartest Rails3 way to accomplish this?

Thanks

@photo = current_user.photos.create(params[:photo])

Keep :project_id in params[:photo]. Use hidden field on form that
submits the data or regular select tag if you let the use choose the
project.
What makes you think that it won't work ? There is no special case
here.

Robert Pankowecki