In the django example, they create a customer query that limits the
range selected to time range defined in the today() function. This
gets 'attached' to the model with EventManager and then applied
automatically when ever an Event object is saved. It only updates the
latest column when all of that criteria is met:
Event.objects.filter(latest=True,
creator=self.creator).today().update(latest=False)
I understand (I think) that the save() override is not relevant here
since the save in django is explicit vs the implicit save in web2py
(correct?).
So I think you are telling me that I need perform this kind of thing
in the controller for web2py.
So can I create a custom filter like the EventQuerySet in the example
and then apply it in the controller? I assume I will have to use this
anywhere an event might get an update? Can I use it with crud?
Am I making sense?
On Jul 29, 11:43 am, mdipierro <mdipie...@cs.depaul.edu> wrote:
> There are many ways.
> If you are using crud, you can do
>
> def fix_latest(form):
> db(db.event.user=auth.user.id).update(latest=False)
> form.vars.latest=True
>
> def index():
> db.event.latest.readable=db.event.latest.writable=False
> form=crud.create(db.event,onvalidation=fix_latest)
> return dict(form=form)
>
> Massimo
>
> On Jul 29, 8:21 am, __future__ <wrigh...@gmail.com> wrote:
>
> > Thanks for all of the replies This is a very responsive group!
>
> > I'm still not clear on how to replicate some of the Django
> > functionality here but at least I think I understand how many-to-many
> > works in web2py.
>
> > I had seen the tagging example before but something about that method
> > bothers me. It reminds of a Clarion DOS app we use at work from 25+
> > years ago. There was a many-to-many relationship between models &
> > options. The solution was to store a list of option ids in a field in
> > the model table. The idea was almost identical except instead of |1|2|
> > 3|4| it was just a regular comma separated list 1,2,3,4.
>
> > Another question about the example I am trying to convert:
>
> > In the django app, the 'last' field in the Event model is used such
> > that only one 'event' per user can have latest=True. They accomplish
> > this by using django's manager class, a custom filter and overriding
> > the save method of the model.
>
> > So in the model file
>
> > def today():
> > now = datetime.now()
> > start = datetime.min.replace(year=now.year, month=now.month,
> > day=now.day)
> > end = (start + timedelta(days=1)) - timedelta.resolution
> > return (start, end)
>
> > class EventQuerySet(QuerySet):
> > def today(self):
> > return self.filter(creation_date__range=today())
>
> > class EventManager(models.Manager):
> > def get_query_set(self):
> > return EventQuerySet(self.model)
>
> > def today(self):
> > self.get_query_set().today()
>
> > class Event(models.Model):
> > #....
> > objects = EventManager()
>
> > def save(self, **kwargs):
> > Event.objects.filter(latest=True,
> > creator=self.creator).today().update(latest=False)
> > super(Event, self).save(**kwargs)
>
> > So before it saves any new event, it sets any other events of that
> > user for today() as latest=false. I am sure there is an easier way to
> > do that but that is what it is in the example.
>
> > What would be the web2py way of doing something like this?
>
> > A working example of this tutorial site is still up at:
>
> > http://startthedark.com.
>
> > A link to the complete source:
>
> > http://github.com/ericflo/startthedark/tree/master
>
> > Thanks again to all for answering my previous question.
>
> > On Jul 28, 6:41 pm, Yarko Tymciurak <yark...@gmail.com> wrote:
>
> > > You should be aware that this "tagging" style is ok, and works - but the
> > > way
> > > it works may not be the right thing for your application.
>
> > > If you have limited references (say ~20 or so per a "many") then this is
> > > simple, efficient, and you can probably manage your many-to-many this way.
>
> > > What this does is stores a set of table references (integers, basically)
> > > as
> > > text delimited by "|", so you would have a reference in this style which
> > > looks (for example) like
>
> > > "|1|27|153|225|"
>
> > > and your code would need to parse it.
>
> > > To have "many" to "many", you would just have cross references like this,
> > > one of the tag-style "many" definitions in each of two tables.
>
> > > I like the traditional way to do this, and that is to define a table to
> > > hold
> > > the many, and there are advantages depending on what you want to do.
>
> > > For example:
>
> > > db.define_table('location',
> > > Field('name'))
> > > db.define_table('transportation',
> > > Field('name'))
>
> > > # many-to-many table - holds what transportation is available where
> > > db.define_table('available',
> > > Field('location', db.location),
> > > Field('transport', db.transportation))
>
> > > Now you can define sets for operations like this:
>
> > > transport_list = ((db.location.id == db.available.location)
> > > & (db.transportation.id == db.available.transport))
> > > for row in transport_list.select():
> > > print row.location.name, row.transport.name
>
> > > On Tue, Jul 28, 2009 at 2:42 PM, Fran <francisb...@googlemail.com> wrote:
>
> > > > On Jul 28, 5:47 pm, __future__ <wrigh...@gmail.com> wrote:
> > > > > I am already confused about how to implement the Django style many-to-
> > > > > many relationship in web2py.
>
> > > > The Many<>Many support native to Web2Py is the Tagging-style:
> > > >http://www.vimeo.com/2720410
>
> > > > F
>
>
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