Question

I’m trying to implement a decorator for custom error pages in web2py
as per one of the haiti Todos. Ref –
http://web2py.com/AlterEgo/default/show/75

I’m trying to keep it as a module in /modules directory so that I can
import it into the controllers and place the decorator appropriately.

I have kept error handling decorator as
/modules/onerror.py

and am importing it like this from a controller say (or.py)-

exec('from applications.%s.modules.onerror import onerror as onerror'
                                                       % request.application)

HTTP object wasn’t available in onerror.py so i did a –

from gluon.http import *

But then I readlized that the request object is also not available to
the decorator as in the line –

filename=os.path.join(request.folder,'views/errors/error%i.html'%status)

I have some doubts –

1. Is /modules directory a good place to keep such a reusable component?

2. Are the modules in the /modules directory automatically loaded as a
   new web2py instance is created? If so how can I access them in a
   controller?

3. Is there a way I can pass the request object to this decorator from
   my controller? Hints are welcome.

My current onerror.py – http://paste.pocoo.org/show/186165/
The way I’m trying to use in a controller – http://paste.pocoo.org/show/186167/

Let me know if I’m doing it in an unobvious way.

Answer 1

Solved through the web2py users mailing list.

you can also use: onerror = load_import(‘onerror’).onerror

HTTP object wasn’t available in onerror.py so i did a –
from gluon.http import *

python modules are normal python modules in web2py as well. They only see
python keywords unless you import them. web2py has 5 special objects
(request, response, session, cache, T) and your app has others (db,
auth, crud). Because they are instantiated at every request, they
cannot import by the module, they have to be passed explicitly to the
functions in the module. Mind that while this is awkward this is what
other frameworks ask to do all the time for all functions. web2py
saves you this for models and controllers.

But then I realized that the request object is also not available to
the decorator as in the line –
filename=os.path.join(request.folder,’views/errors/error
%i.html’%status)
I have some doubts –
1. Are the modules in the /modules directory automatically loaded as a
new web2py instance is created? If so how can I access them?

No. They are normal python modules. You have to import them to use
them.

2. Is there a way I can pass the request object to this decorator from
   my controller? Hints are welcome.

You need a meta decorator def meta_decoration(something):
def actual_decorator(f,something=something):
do_whatever_you_want()
return f()
return decorator @meta_decorator(request) def function_to_be_decorated(): return dict() Anyway you do not need this
decorator. Look into routes.examples.py for routes_onerror. There is
a simple way to do what you want.