#table for tracks
 db.define_table('track',
            Field('artist'),
            Field('album'),
            Field('title'),
            Field('duration', 'float'),
            ......
            )
#table for playlists
db.define_table('playlist',
            Field('title')
            )
#table for references
db.define_table('playlist_reference',
            Field('playlist', 'reference playlist'),
            Field('track','reference track')
            )

def get_playlist_tracks():
title = request.vars.title
tracks = []

q = (title == db.playlist.title)

#searches the playlist database for the playlist that
#matches the title of the playlist whose tracks I want to retrieve
#and gives me its id
plist_id = db(q).select().first().id

#returns all the references in which that playlist appears
q = (plist_id == db.playlist_reference.playlist)
refs = db(q).select(db.playlist_reference.ALL)

#for each reference I get the track id and append to tracks array
for i, r in enumerate(refs):
    t_id = r.track
    q = (t_id == db.track.id)
    track = db(q).select(db.track.ALL)
    print track
    tracks.append(track)

return response.json(dict(
    tracks=tracks)
)