On Wed, Sep 27, 2006 at 03:57:01PM +0200, Alberto Valverde wrote:
>
>
> On Sep 27, 2006, at 2:38 PM, Timur Izhbulatov wrote:
>
> >
> > On Wed, Sep 27, 2006 at 01:29:05PM +0200, Alberto Valverde wrote:
> >>
> >> On Sep 27, 2006, at 1:10 PM, Timur Izhbulatov wrote:
> >>
> >>>
> >>> Hi,
> >>>
> >>> I got a problem using @exception_handler together with Cheetah.
> >>>
> >>> Consider a situation:
> >>>
> >>> # in cheetah1/controllers.py
> >>> from turbogears import controllers, expose, exception_handler
> >>>
> >>> class Root(controllers.RootController):
> >>> def get_data(self):
> >>> raise ValueError('Error!')
> >>> return dict(a=1)
> >>>
> >>> def error(self, tg_exceptions=None):
> >>> return dict(exception=str(tg_exceptions))
> >>>
> >>> @exception_handler(error, rules="True")
> >>> @expose(template="cheetah:cheetah1.templates.site")
> >>> def index(self):
> >>> data = self.get_data()
> >>> return data
> >>>
> >>> # in cheetah1/templates/site.tmpl
> >>> a: $a
> >>>
> >>> I expect @exception_handler to handle the ValueError exception
> >>> before @expose
> >>> renders the template. But it looks like @expose is called before
> >>> @exception_handler and Cheetah.Template.NotFound raises. In this
> >>> situation I
> >>> have to handle the exception in the method body and change the
> >>> template
> >>> dynamicaly:
> >>>
> >>> @expose(template="cheetah:cheetah1.templates.site")
> >>> def index(self):
> >>> try:
> >>> data = self.get_data()
> >>> except ValueError, error:
> >>> return (dict
> >>> (tg_template='cheetah:cheetah1.templates.error',
> >>> error=error))
> >>> return data
> >>>
> >>> But @exception_handler is not used and I lose all the benefits it
> >>> gives! Is it
> >>> posible to solve this problem without writing custom template
> >>> plugin/decorator/whatever?
> >>>
> >>> Thanks in advance,
> >>
> >> errorhandling only catches exceptions raised *inside* controller
> >> methods (well, and SA's run_with_transaction to catch db backend
> >> exceptions). The exception from Cheetah is raised somewhere inside
> >> expose so errorhandling can't help you there, sorry :(
> >
> > Yes, but the ValueError exception is raised inside my method. I
> > mean this is an
> > ordinary sutiation for the MVC pattern when Controller tries to get
> > some
> > business data from Model and tells View to either render the page
> > with data or
> > show an error page. And if Controller fails do get the data from
> > Model, View
> > should not try to render the page.
> >
> > Apllying the above logic to my example assumes that the ValueError
> > should be
> > handled before View attempts to render the page.
> >
> > This code
> > @expose(template="cheetah:cheetah1.templates.site")
> > def index(self):
> > data = self.get_data()
> > return data
> >
> > works as expected. It raises an exception. I try to handle it using
> > @exception_handler and get another exception raised inside @expose.
> >
> > Why is that happening? Is it happening because TG attempts to
> > render the page
> > before doing error handling? No! I can see errorhandling.try_call
> > called from
> > controllers._execute_func to get controller method output. So why
> > the ValueError
> > exception is not handled there?..
> >
> > Maybe I'm missing something? Could you please shed some light on
> > the situation?
>
> Sorry, I had read you wrong. I assumed you wanted to trap the
> exception raised by Cheetah, not the ValueError raised inside your
> controller method.
>
> Studying it in more detail I think I've found the cause:
>
> When you return a dict from "error", this dict is returned instead of
> the dict "index" would have normally returned and passed thorugh
> *index*'s expose, therefore yielding the exception you're getting
> because the template defined by that expose doesn't exist.
Ah, I got it finally!
BTW, the template does exist. NotFound means Cheetah can't substitute $a because
it doesn't exist in the "index" dict. But it doesn't really matter.
The matter is that I couldn't find any other @exception_handler example except
the one
in the official documentation and tried to use it as is. Hence the result =)
> Your use-case could be accomplished if you exposed "error" (perhaps
> with a custom error template) so it returns a string therefore
> bypassing index's expose's template loading. something like
>
> @expose(template='cheetah:cheetah1.templates.error')
> def error(self, tg_exceptions=None):
> return dict(exception=str(tg_exceptions))
I think your example with exposed handler should be added to the docs.
> Sorry for misleading you before in my prev. post.
> HTH,
> Alberto
Thanks for the clarification! Everything is working now.
--
Timur Izhbulatov
OILspace, 26 Leninskaya sloboda, bld. 2, 2nd floor, 115280 Moscow, Russia
P:+7 495 105 7245 + ext.205 F:+7 495 105 7246 E:[EMAIL PROTECTED]
Building Successful Supply Chains - One Solution At A Time.
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