[web2py] When i JOIN something it goes ok, but if there is no join i got an error..

[Bart]

Hi all,

Just starting with Web2py and i feel like a kid in a play garden. ;)

Ok my problem, i am trying to make a simple JOIN but when i do that i
have a problem with my views.
My controlle looks like this:

def read():

    thispage = db.topics[request.args(0)]

    if not thispage:
      redirect(URL(r=request, f='read'))

    if auth.user_id:
        form = form = SQLFORM(db.replys)
        form.vars.topic_id = request.args(0)
        form.vars.user_id = auth.user_id
        if form.accepts(request.vars, session):
            response.flash = 'Topic created!'
    else:
       form = 'need to login to reply'

    db(db.topics.id==request.args(0)).select()[0]
    #topics = db(db.topics.id==request.args(0)).select(db.topics.id==
db.replys.topic_id)
    #replys =
db(db.replys.topic_id==request.args(0)).select(db.replys.ALL,
orderby=~db.replys.posted)
    #query = (db.topics.id==db.replys.topic_id)&(db.topics.id ==
request.args(0))
    rows= db(db.topics.id== request.args(0)).select(db.topics.title,
db.topics.content,
                                                    db.replys.content,
left=db.topics.on(db.topics.id==db.replys.topic_id))


    return dict(rows=rows,form=form)

My view looks like this:

{{extend 'layout.html'}}

   {{for row in rows:}}
  <h1> {{=row.topics.title}} </h1>
  <p>  {{=row.topics.content}}</p>
  {{pass}}

   {{for row in rows:}}
      <hr>
  <p>  {{=row.replys.content}}</p>
  {{pass}}


  <b> {{=form}} </b>
When i have a few reply's then i have row.topics.titles and
row.topics.content as the same amount as the row.replys.content.
When i don't have a reply, then i don get the record back from topics.

Now my question: How do i get one time the topics record back, and
when there is none replys just the the record of the topic?

What am i missing at this point?

Thanks for the help.
regards, Bart