Files
deb-python-pecan/pecan/hooks.py
Jonathan LaCour bed5cbfa14 After a full-scale scan with pep8.py and pyflakes, identified and
resolved most of our PEP8 compliance issues.
2012-03-11 09:52:25 -07:00

339 lines
11 KiB
Python

import sys
from inspect import getmembers
from webob.exc import HTTPFound
from util import iscontroller, _cfg
from routing import lookup_controller
__all__ = [
'PecanHook', 'TransactionHook', 'HookController',
'RequestViewerHook'
]
def walk_controller(root_class, controller, hooks):
if not isinstance(controller, (int, dict)):
for name, value in getmembers(controller):
if name == 'controller':
continue
if name.startswith('__') and name.endswith('__'):
continue
if iscontroller(value):
for hook in hooks:
value._pecan.setdefault('hooks', []).append(hook)
elif hasattr(value, '__class__'):
if name.startswith('__') and name.endswith('__'):
continue
walk_controller(root_class, value, hooks)
class HookController(object):
'''
A base class for controllers that would like to specify hooks on
their controller methods. Simply create a list of hook objects
called ``__hooks__`` as a member of the controller's namespace.
'''
__hooks__ = []
class __metaclass__(type):
def __init__(cls, name, bases, dict_):
walk_controller(cls, cls, dict_['__hooks__'])
class PecanHook(object):
'''
A base class for Pecan hooks. Inherit from this class to create your
own hooks. Set a priority on a hook by setting the ``priority``
attribute for the hook, which defaults to 100.
'''
priority = 100
def on_route(self, state):
'''
Override this method to create a hook that gets called upon
the start of routing.
:param state: The Pecan ``state`` object for the current request.
'''
return
def before(self, state):
'''
Override this method to create a hook that gets called after
routing, but before the request gets passed to your controller.
:param state: The Pecan ``state`` object for the current request.
'''
return
def after(self, state):
'''
Override this method to create a hook that gets called after
the request has been handled by the controller.
:param state: The Pecan ``state`` object for the current request.
'''
return
def on_error(self, state, e):
'''
Override this method to create a hook that gets called upon
an exception being raised in your controller.
:param state: The Pecan ``state`` object for the current request.
:param e: The ``Exception`` object that was raised.
'''
return
class TransactionHook(PecanHook):
'''
A basic framework hook for supporting wrapping requests in
transactions. By default, it will wrap all but ``GET`` and ``HEAD``
requests in a transaction. Override the ``is_transactional`` method
to define your own rules for what requests should be transactional.
'''
def __init__(self, start, start_ro, commit, rollback, clear):
'''
:param start: A callable that will bind to a writable database and
start a transaction.
:param start_ro: A callable that will bind to a readable database.
:param commit: A callable that will commit the active transaction.
:param rollback: A callable that will roll back the active
transaction.
:param clear: A callable that will clear your current context.
'''
self.start = start
self.start_ro = start_ro
self.commit = commit
self.rollback = rollback
self.clear = clear
def is_transactional(self, state):
'''
Decide if a request should be wrapped in a transaction, based
upon the state of the request. By default, wraps all but ``GET``
and ``HEAD`` requests in a transaction, along with respecting
the ``transactional`` decorator from :mod:pecan.decorators.
:param state: The Pecan state object for the current request.
'''
controller = getattr(state, 'controller', None)
if controller:
force_transactional = _cfg(controller).get('transactional', False)
else:
force_transactional = False
if state.request.method not in ('GET', 'HEAD') or force_transactional:
return True
return False
def on_route(self, state):
state.request.error = False
if self.is_transactional(state):
state.request.transactional = True
self.start()
else:
state.request.transactional = False
self.start_ro()
def before(self, state):
if self.is_transactional(state) and not state.request.transactional:
self.clear()
state.request.transactional = True
self.start()
def on_error(self, state, e):
#
# If we should ignore redirects,
# (e.g., shouldn't consider them rollback-worthy)
# don't set `state.request.error = True`.
#
trans_ignore_redirects = (
state.request.method not in ('GET', 'HEAD')
)
if state.controller is not None:
trans_ignore_redirects = (
_cfg(state.controller).get(
'transactional_ignore_redirects',
trans_ignore_redirects
)
)
if type(e) is HTTPFound and trans_ignore_redirects is True:
return
state.request.error = True
def after(self, state):
if state.request.transactional:
action_name = None
if state.request.error:
action_name = 'after_rollback'
self.rollback()
else:
action_name = 'after_commit'
self.commit()
#
# If a controller was routed to, find any
# after_* actions it may have registered, and perform
# them.
#
if action_name:
controller = getattr(state, 'controller', None)
if controller is not None:
actions = _cfg(controller).get(action_name, [])
for action in actions:
action()
self.clear()
class RequestViewerHook(PecanHook):
'''
Returns some information about what is going on in a single request. It
accepts specific items to report on but uses a default list of items when
none are passed in. Based on the requested ``url``, items can also be
blacklisted.
Configuration is flexible, can be passed in (or not) and can contain
some or all the keys supported.
``items``
---------
This key holds the items that this hook will display. When this key is
passed only the items in the list will be used. Valid items are *any*
item that the ``request`` object holds, by default it uses the
following:
* path
* status
* method
* controller
* params
* hooks
.. :note::
This key should always use a ``list`` of items to use.
``blacklist``
-------------
This key holds items that will be blacklisted based on ``url``. If
there is a need to ommit urls that start with `/javascript`, then this
key would look like::
'blacklist': ['/javascript']
As many blacklisting items as needed can be contained in the list. The hook
will verify that the url is not starting with items in this list to display
results, otherwise it will get ommited.
.. :note::
This key should always use a ``list`` of items to use.
For more detailed documentation about this hook, please see
:ref:`requestviewerhook`
'''
available = ['path', 'status', 'method', 'controller', 'params', 'hooks']
def __init__(self, config=None, writer=sys.stdout, terminal=True,
headers=True):
'''
:param config: A (optional) dictionary that can hold ``items`` and/or
``blacklist`` keys.
:param writer: The stream writer to use. Can redirect output to other
streams as long as the passed in stream has a
``write`` callable method.
:param terminal: Outputs to the chosen stream writer (usually
the terminal)
:param headers: Sets values to the X-HTTP headers
'''
if not config:
self.config = {'items': self.available}
else:
if config.__class__.__name__ == 'Config':
self.config = config.as_dict()
else:
self.config = config
self.writer = writer
self.items = self.config.get('items', self.available)
self.blacklist = self.config.get('blacklist', [])
self.terminal = terminal
self.headers = headers
def after(self, state):
# Default and/or custom response information
responses = {
'controller': lambda self, state: self.get_controller(state),
'method': lambda self, state: state.request.method,
'path': lambda self, state: state.request.path,
'params': lambda self, state: [
(p[0].encode('utf-8'), p[1].encode('utf-8'))
for p in state.request.params.items()
],
'status': lambda self, state: state.response.status,
'hooks': lambda self, state: self.format_hooks(state.app.hooks),
}
is_available = [
i for i in self.items
if i in self.available or hasattr(state.request, i)
]
terminal = []
headers = []
will_skip = [
i for i in self.blacklist
if state.request.path.startswith(i)
]
if will_skip:
return
for request_info in is_available:
try:
value = responses.get(request_info)
if not value:
value = getattr(state.request, request_info)
else:
value = value(self, state)
except Exception, e:
value = e
terminal.append('%-12s - %s\n' % (request_info, value))
headers.append((request_info, value))
if self.terminal:
self.writer.write(''.join(terminal))
self.writer.write('\n\n')
if self.headers:
for h in headers:
key = str(h[0])
value = str(h[1])
name = 'X-Pecan-%s' % key
state.response.headers[name] = value
def get_controller(self, state):
'''
Retrieves the actual controller name from the application
Specific to Pecan (not available in the request object)
'''
path = state.request.pecan['routing_path'].split('/')[1:]
controller, reminder = lookup_controller(state.app.root, path)
return controller.__str__().split()[2]
def format_hooks(self, hooks):
'''
Tries to format the hook objects to be more readable
Specific to Pecan (not available in the request object)
'''
str_hooks = [str(i).split()[0].strip('<') for i in hooks]
return [i.split('.')[-1] for i in str_hooks if '.' in i]