On Fri, Jun 4, 2010 at 9:11 AM, Yarko Tymciurak <[email protected]> wrote: > > > On Jun 4, 10:58 am, Doug Warren <[email protected]> wrote: >> I don't believe I want to local_import my db.py file as it's already >> set up by the environment correct? > > Correct - you do not want / need to import your db.py. > > As long as it is in your models folder (by default it is), it's > already in your request context before your controller is called.
Yes but as I mentioned in my original E-Mail, I was unable to get a function defined in the model file to be visible to the controller hence the original question. :) I thought about it a bit during my drive and think I will try (using the below example) something like: def create_object... ... co = create_object controller.py co( template_id ...) > >> >> What I'm asking for is a way to keep all of the code that relates to >> the model in one place and to invoke it from controllers. That is if >> I define 5 tables for the model I'd expect to write helper functions >> to manipulate all 5 tables and not to have the controller know the >> intimate details of the model. That's the concept behind Object >> Orientated programming isn't it? Objects are black boxes to other >> objects other than their public facing interface. > > Right - but DAL is just a Data abstraction layer (i.e. an SQL adapter, > if you will), not an ORM (i.e. there's not the level of object- > oriented abstraction that you would expect w/ an orm - it's lower > level) > > So in web2py, with DAL you have knowledge of your table layout > (without direct knowledge / need for the specific back ends SQL). > > You'll also find that forms, and validators are coupled to table > structure, so if / as you try to abstract away from table definitions, > you will run into this. > > I'm sure others will add more comments... > >> >> On Fri, Jun 4, 2010 at 8:56 AM, Yarko Tymciurak >> >> <[email protected]> wrote: >> >> > On Jun 4, 10:43 am, Doug Warren <[email protected]> wrote: >> >> Traditionally when I've written MVC style applications, the model >> >> would contain not only the data representing the objects but also the >> >> data for manipulating the objects. I'm not sure how that same >> >> relation applies to web2py. >> >> >> If I have a model that defines 4-5 tables, 2 of them are just foreign >> >> key lookups, and creating a new object involves inserting data into 3 >> >> of the tables, it seems that I would want a create_object method in my >> >> model file. >> >> >> So I write something like: >> >> >> def create_object(owner_id=None, template=None): >> >> # Some sanity checking on the above >> >> new_object = db.objects.insert(template_id=template.id, >> >> person_id=owner_id) >> >> >> widgets = db.template_widget(db.template_widget.thingy_template_id >> >> == template.id).select() >> >> for widget in widgets: db.thingy_widget.insert(widget_id = >> >> widget.id, thingy_id = new_object) >> >> >> whatchymacallits = >> >> db.template_whatchymacallit(db.template_whatchymacallit.thingy_template_id >> >> == template.id).select() >> >> for whatchymacallit in whatchymacallits: >> >> db.thingy_whatchymacallit.insert(whatchymacallit_id = >> >> whatchymacallit.id, thingy_id = new_object) >> >> >> return new_object >> >> >> and place that into my db.py. Now the controller has a function like: >> >> def create(): >> >> form = SQLFORM.factory( Field('template', >> >> requires=IS_IN_SET(__get_templates()))) >> >> if form.accepts(request.vars, session): >> >> foo = db.create_object(owner_id=auth.auth_id, >> >> template_name=form.vars.template) >> >> response.flash = "Created" >> >> elif form.errors: >> >> response.flash = "Error (hacker)" >> >> >> Well db is referring to the DAL db not the db.py, from db import >> >> create_object gives a name not found error, so I'm at a loss as to how >> >> to define functions that work upon the model and can be invoked from >> >> one or more controllers. >> >> > I'm not sure what exactly you are saying here - but to import, use >> > local_import() >> > (seehttp://www.web2py.com/book/default/section/4/18?search=local_import) >> >> > BUT before you do, here is some background: >> >> > When a request comes into web2py, here's what happens (roughly): >> >> > web2py parses the request url, and sets up an environment to call the >> > appropriate application / controller / function; >> > Part of that setup involves running all the files in your app's model >> > folder (so that db connections, table definitions, etc. are all "there >> > for you"); >> >> > This means you can put your files in the models folder, and they will >> > be run (defined) before the call to your controller. >> >> > Then, your controller / function is called. >> >> > local_import will pull in definitions / modules from your >> > application's modules folder, but you can (for development certainly) >> > just put your file in your models folder. >> > When you really want to reduce what gets run at _each_ request, you >> > might want to look at what to move to modules, so that you're only >> > pulling in those files when needed. >> >> > As for db - DAL: db is the "global" and "default" name for the db >> > connection string (it is so named and setup in the default models/ >> > db.py file). You can change the name of this variable as you like >> > (or change your imports). >> >> > Hope this at least helps point you out of the forrest. >> >> > Regards, >> > - Yarko >> >> Are there any non-trivial example >> >> applications for web2py? Most of the ones that I have seen assumes >> >> that all data you need in the database can be supplied from a form and >> >> that's not the case I run into over and over again.
