On Aug 19, 2006, at 9:24 AM, Sanjay wrote:
>
> Hi Alberto,
>
> Thanks for such an overwhelming response and support!
No problem ;)
> But, with my terrible ignorance on python and TG internals, I could
> not
> succeed trying your example. Got this error:
>
> Traceback (most recent call last):
> File "./start-ierr.py", line 26, in ?
> from ierr.controllers import Root
> File "/Data/LearnTG/ierr/ierr/controllers.py", line 14, in ?
> class Root(controllers.RootController):
> File "/Data/LearnTG/ierr/ierr/controllers.py", line 30, in Root
> @errorhandling.dispatch_error.when("isinstance(tg_exceptions,
> IntegrityError)")
> File
> "/usr/lib/python2.4/site-packages/TurboGears-0.9a7-py2.4.egg/
> turbogears/genericfunctions.py",
> line 20, in when
> return self._decorate(cond, "primary%d" % order)
> File
> "/usr/lib/python2.4/site-packages/RuleDispatch-0.5a0.dev_r2115-
> py2.4-linux-i686.egg/dispatch/functions.py",
> line 577, in _decorate
> cond = self.parseRule(cond,frame=frame) or cond
> File "<string>", line 10, in parseRule
> File
> "/usr/lib/python2.4/site-packages/RuleDispatch-0.5a0.dev_r2115-
> py2.4-linux-i686.egg/dispatch/functions.py",
> line 440, in parseRule
> return self.parse(rule, frame.f_locals, frame.f_globals)
> File
> "/usr/lib/python2.4/site-packages/RuleDispatch-0.5a0.dev_r2115-
> py2.4-linux-i686.egg/dispatch/functions.py",
> line 326, in parse
> return parse_expr(expr_string,builder)
> File
> "/usr/lib/python2.4/site-packages/RuleDispatch-0.5a0.dev_r2115-
> py2.4-linux-i686.egg/dispatch/ast_builder.py",
> line 383, in parse_expr
> return build(builder, parser.expr(expr).totuple(1)[1])
> File
> "/usr/lib/python2.4/site-packages/RuleDispatch-0.5a0.dev_r2115-
> py2.4-linux-i686.egg/dispatch/ast_builder.py",
> line 378, in build
> return production[nodelist[0]](builder,nodelist)
> File
> "/usr/lib/python2.4/site-packages/RuleDispatch-0.5a0.dev_r2115-
> py2.4-linux-i686.egg/dispatch/ast_builder.py",
> line 178, in power
> return com_call_function(builder,nodelist,node[2])
> File
> "/usr/lib/python2.4/site-packages/RuleDispatch-0.5a0.dev_r2115-
> py2.4-linux-i686.egg/dispatch/ast_builder.py",
> line 284, in com_call_function
> return builder.CallFunc(primaryNode, args, kw, star_node,
> dstar_node)
> File "build/bdist.linux-i686/egg/dispatch/predicates.py", line 545,
> in method
> File "build/bdist.linux-i686/egg/dispatch/predicates.py", line 170,
> in CallFunc
> File
> "/usr/lib/python2.4/site-packages/RuleDispatch-0.5a0.dev_r2115-
> py2.4-linux-i686.egg/dispatch/ast_builder.py",
> line 378, in build
> return production[nodelist[0]](builder,nodelist)
> File
> "/usr/lib/python2.4/site-packages/RuleDispatch-0.5a0.dev_r2115-
> py2.4-linux-i686.egg/dispatch/ast_builder.py",
> line 10, in <lambda>
> _name = lambda builder,nodelist: builder.Name(nodelist[1])
> File "build/bdist.linux-i686/egg/dispatch/predicates.py", line
> 58, in
> Name
> NameError: IntegrityError
You need to import the exception raised by SQLAlchemy into the
namespace the dispatch rule (the string passed as an argument to
"dispatch_error.when") is defined or else you'll get the NameError
you're getting. It should read:
from sqlalchemy.exceptions import SQLError
...
@errorhandling.dispatch_error.when("isinstance(tg_exceptions,
SQLError)")
def handle_SQLError(....):
.....
See how SQLError needs to be defined in the same namespace the rule
is defined in. One note, I believe watching for a SQLError is more
portable than watching for a IntegrityError because the later is DB
driver specific while the former is a SA exception.
> Then, trying to diagnose the error by simplification, I tried this
> code:
>
> @errorhandling.dispatch_error.when("True")
> def handle_IE(controller, tg_source, tg_errors, tg_exceptions,
> *args, **kw):
> log.debug("An IntegrityError (%s) ocurred in method %r of
> controller %r" %
> tg_exceptions, tg_source, controller)
> turbogears.flash("An integrity error ocurred")
>
> But, then got this error while execution:
>
> 500 Internal error
>
> The server encountered an unexpected condition which prevented it from
> fulfilling the request.
>
> Page handler: <bound method Root.createsanjay of
> <ierr.controllers.Root
> object at 0xb767cc0c>>
> Traceback (most recent call last):
> File
> "/usr/lib/python2.4/site-packages/CherryPy-2.2.1-py2.4.egg/cherrypy/
> _cphttptools.py",
> line 105, in _run
> self.main()
> File
> "/usr/lib/python2.4/site-packages/CherryPy-2.2.1-py2.4.egg/cherrypy/
> _cphttptools.py",
> line 254, in main
> body = page_handler(*virtual_path, **self.params)
> File "<string>", line 3, in createsanjay
> File
> "/usr/lib/python2.4/site-packages/TurboGears-0.9a7-py2.4.egg/
> turbogears/controllers.py",
> line 331, in expose
> output = database.run_with_transaction(
> File "<string>", line 5, in run_with_transaction
> File
> "/usr/lib/python2.4/site-packages/TurboGears-0.9a7-py2.4.egg/
> turbogears/database.py",
> line 282, in sa_rwt
> errorhandling.dispatch_error(controller, real_func, None, e,
> *args,
> **kw)
> File "<string>", line 5, in dispatch_error
> File "/Data/LearnTG/ierr/ierr/controllers.py", line 32, in handle_IE
> log.debug("An IntegrityError (%s) ocurred in method %r of
> controller %r" %
> TypeError: not enough arguments for format string
Ooops, the sample code had a typo, it should read:
log.debug("An IntegrityError (%s) ocurred in method %r of controller %
r" %
(tg_exceptions, tg_source, controller))
(Notice that the arguments for the format string are a tuple)
> Not able to diagnose. I am using 9a7.
>
> Another point concerning me -
>
> The pattern I think to use is someting like this:
>
> @expose(template="tm.templates.form")
> def edit_person(self, tg_errors=None, tg_exceptions=None):
> if tg_errors:
> flash("Problem validating! Please correct")
> if tg_exceptions:
> flash("Problem saving! Please correct")
> .
> .
> .
>
>
> @expose()
> @turbogears.validate(form=person_form)
> @turbogears.error_handler(edit_person)
> @turbogears.exception_handler(edit_person)
> def save(self, name):
> u = User(name=name)
> u.flush()
>
> I guess this is the most easy way to handle errors and exceptions
> while
> data entry by user. Need guidence on the way to achieve this pattern
> with the patch.
Actually, the above code should work as-is ;) Just a note, if you
only want to branch to "edit_person" in case a SQLError exception is
raised by SA you can specialize exception_handler with a dispatch rule:
from sqlalchemy.exceptions import SQLError
@turbogears.exception_handler(edit_person, "isinstance(tg_exceptions,
SQLError)")
def save(....):
....
It'll probably help to take a look at
http://trac.turbogears.org/turbogears/wiki/HowDoesErrorHandlingWork
Alberto
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