[SQLObject] Problem with re-ordering rows.

[Nick M. <nmu...@lo...>]

Hi all,

I'm attempting to write an app that will let me create a set of Acts, 
where each Act can contain some Scenes, and each Scene can contain some 
Lines. Simple enough, but I also want to be able to rearrange the Lines 
in a Scene (and, ideally, the Scenes in an Act)

To me it seems like I need something along the lines of a linked list to 
be able to do that, however I've come a bit unstuck trying to implement 
this into SQLObject classes.

I've come up with the following so far, but I'm having trouble assigning 
'prev' and 'next' to any Lines I create:

class Act(SQLObject):
     owner = ForeignKey('Play')
     title = UnicodeCol()
     scenes = MultipleJoin('Scene', joinColumn="owner_id")
     created = DateTimeCol(default=datetime.now)

class Scene(SQLObject):
     owner = ForeignKey('Act')
     title = UnicodeCol()
     lines = MultipleJoin('Line', joinColumn="owner_id")
     created = DateTimeCol(default=datetime.now)
     prev = SingleJoin('Scene')
     next = SingleJoin('Scene')

class Line(SQLObject):
     owner = ForeignKey('Scene')
     text = UnicodeCol()
     prev = SingleJoin('Line', addRemoveName='Prev')
     next = SingleJoin('Line', addRemoveName='Next')
     created = DateTimeCol(default=datetime.now)


 >>> play = Play(owner=me, title="moo", description="moo")
 >>> act = Act(owner=play, title="Act I")
 >>> scene = Scene(owner=act, title="Scene 1")
 >>> line1 = Line(owner=scene, text="moo")
 >>> line2 = Line(owner=scene, text="moo2")
 >>> line1.addNext(line2)
Traceback (most recent call last):
   File "<console>", line 1, in ?
AttributeError: 'Line' object has no attribute 'addNext'
 >>> line1.next = line2
Traceback (most recent call last):
   File "<console>", line 1, in ?
AttributeError: can't set attribute


Is there a better way to go about doing this?


Thanks,

Nick Murdoch