As Massimo pointed out, the philosophy and approach w/in django & web2py is different.
You will probably want to step back from the django solution one step - from "here's how it's done in django" to what is being accomplished, and how it's done in django. Then you will more readily get to "how would you do this in web2py? would you do it the similarly? differently? would a different structure to address what you want to accomplish work better w/ web2py?" While not everything needs to go this route, I suggest everytime it seems like you are having a hard trime translating from one place to the other, step back one level of abstraction - reconstruct what is the target to accomplish, and review the approaches between the two. On Wed, Jul 29, 2009 at 10:13 PM, mdipierro <mdipie...@cs.depaul.edu> wrote: > > If you build the model, and empty actions which a docstring explaining > what the should do, I can help filling the blanks. > > On Jul 29, 8:37 pm, __future__ <wrigh...@gmail.com> wrote: > > I would like it to be functionally as similar to the original as > > possible (with maybe a couple of enhancements :-) ) > > > > I think in the building of it, people will really appreciate a lot of > > the things that web2py does for you in the process.. I personally find > > seemingly little things like the handling of routes and default views > > extremely helpful in the process of actually making/testing things. > > > > I was actually wondering about the latest field as I was posting all > > of those examples... It has been almost a year since I walked through > > that Django tutorial and I think it had something to do with the > > archive or maybe the following behavior.. In any case, until I look > > into it, I can't really argue for its purpose... though I think it was > > necessary for some reason. > > > > I don't think GAE is really important to this example. Not everything > > worth doing is going to be GAE friendly and I think this is a good > > case study for some of the features it exposes like the > > '"twitteresque" following behavior, etc.. > > > > I also like that it gives Django people a 1-1 comparison of how to > > accomplish similar behavior with a different philosophy (as you say). > > > > Thanks for offering your help. > > > > On Jul 29, 8:20 pm, mdipierro <mdipie...@cs.depaul.edu> wrote: > > > > > This is an excellent idea and you can count on my help. > > > > > One decision you need to make is how close you want to the > > > "translation" to be to the original. > > > - do you need the same actions? (I assume yes) > > > - can you use joins? (I assume yes, but in this case it will not run > > > on GAE) > > > - do you need the same tables? (probably yes) > > > - do you need the same table and field names? (I would change some of > > > them) > > > - Why do you need the latest field? I think this is redundant since > > > you can select the latest using the post date. > > > - How should users search for other users to follow? (by name, by > > > email, by secret code) > > > > > On Jul 29, 7:44 pm, __future__ <wrigh...@gmail.com> wrote: > > > > > > Thank you for the quick reply! > > > > > > I think this is starting to click a little more for me. I have > > > > purchased the book and I have the updated chapters you posted for > > > > 6,7,8 that I have been using as a reference. > > > > > > Unfortunately, my mind struggles with abstractions unless presented > > > > with a concrete example. It is probably why I am still a mediocre > > > > programmer after all of these years :) > > > > > > Could you possibly assist me with some more hints along these > lines... > > > > you can check out the working end result of all of that djangoese at: > > > > > >http://startthedark.com > > > > > > My ultimate goal is to rebuild that app in web2py and describe the > > > > process in detail along with screencasts. This startthedark was a > > > > project based on a django screencast tutorial series called "Django > > > > from the ground up" that I found very useful when learning Django. > > > > > > Thanks for all of the help. > > > > > > __future__ > > > > > > On Jul 29, 7:11 pm, mdipierro <mdipie...@cs.depaul.edu> wrote: > > > > > > > These are good questions. web2py does not have something like > Django > > > > > managers and you have to achieve the same goal differently. This is > > > > > because of different in design philosophy. > > > > > > > Django has an ORM, web2py has a DAL. In Django a model maps a table > > > > > into an object so you can override the methods of that object. > > > > > web2py prefers to be a lower lever than that. the web2py DAL > > > > > expressions map 1-to-1 into SQL queries. For example we do not have > a > > > > > save() methods. We do have an insert() method. You cannot override > it > > > > > because it does not belong to the table (model) but it belong to > the > > > > > database. (technically you could override it but you would be doing > > > > > for all tables). > > > > > > > What in Django you achieve by modifying the model, in web2py you > > > > > achieve my modifying the forms. Forms can be associated to two > > > > > functions: onvalidation, onaccept. The former is executed after > > > > > validation before any database IO, the latter is executed after > > > > > database IO. > > > > > > > You can define these functions in the model (they are just > functions, > > > > > not class methods) but you still need to be specific about which > form > > > > > they apply to (onvalidation=...). > > > > > > > Hope this helps. > > > > > > > Massimo > > > > > > > On Jul 29, 3:18 pm, __future__ <wrigh...@gmail.com> wrote: > > > > > > > > Looking at my post, I can see where not knowing Django would be > an > > > > > > impediment to understanding... :) > > > > > > > > Let me try again (and please bare with me because I am *not* an > expert > > > > > > on Django). > > > > > > > > Django has these things called Managers: > > > > > > > >http://docs.djangoproject.com/en/dev/topics/db/managers/ > > > > > > > > from the Django docs: > > > > > > > > class Manager > > > > > > > > A Manager is the interface through which database query > operations are > > > > > > provided to Django models. At least one Manager exists for every > model > > > > > > in a Django application. > > > > > > > > You can create your own Managers and use them with your models. > You > > > > > > can create custom QuerySets (filters basically) and use them with > your > > > > > > Managers. > > > > > > > > In the example I gave, he creates a function today(): > > > > > > > > from datetime import datetime, timedelta > > > > > > 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) > > > > > > > > Then a custom QuerySet (EventQuerySet) that extends the base > QuerySet > > > > > > with a today method which uses the function he defined above. > > > > > > > > self.filter(creation_date__range=today()) # __range is part of > the > > > > > > django filtering syntax > > > > > > > > Then he creates a custom Manager (EventManager) and assigns it to > > > > > > 'objects' in his model: > > > > > > > > class Event(models.Model) > > > > > > #.... > > > > > > objects = EventManager() > > > > > > > > So now when he calls Event.objects he is really calling an > instance of > > > > > > the EventManager() > > > > > > > > He does one more thing though.. All models have a default save > method > > > > > > which is called explicitly to commit changes. He overrides the > > > > > > inherited default save method with this one: > > > > > > > > def save(self, **kwargs): > > > > > > Event.objects.filter(latest=True, > > > > > > creator=self.creator).today().update(latest=False) > > > > > > super(Event, self).save(**kwargs) > > > > > > > > So now whenever an Event object is saved, this code will execute > > > > > > regardless of where it happens because save is a model method. > > > > > > > > I think I explained that correctly (possibly not well :) > > > > > > > > What would be the best (or most DRY) way to do something like > this in > > > > > > web2py? > > > > > > > > Thanks again to all for indulging my questions... > > > > > > > > On Jul 29, 1:51 pm, Fran <francisb...@googlemail.com> wrote: > > > > > > > > > On Jul 29, 6:51 pm, __future__ <wrigh...@gmail.com> wrote: > > > > > > > > > > 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? > > > > > > > > > I don't quite follow the example (I'm not familiar with Django) > but > > > > > > > what I think you're looking for is: > > > > > > > crud.settings.create_onvalidation = lambda form: > mycustomfilter(form) > > > > > > > > > F > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "web2py-users" group. To post to this group, send email to web2py@googlegroups.com To unsubscribe from this group, send email to web2py+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/web2py?hl=en -~----------~----~----~----~------~----~------~--~---
