/usr/lib/python3/dist-packages/pecan/rest.py is in python3-pecan 1.2.1-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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import warnings
from webob import exc
import six
from .core import abort
from .decorators import expose
from .routing import lookup_controller, handle_lookup_traversal
from .util import iscontroller, getargspec
class RestController(object):
'''
A base class for ``REST`` based controllers. Inherit from this class
to implement a REST controller.
``RestController`` implements a set of routing functions which override
the default pecan routing with behavior consistent with RESTful routing.
This functionality covers navigation to the requested resource
controllers, and the appropriate handling of both the common (``GET``,
``POST``, ``PUT``, ``DELETE``) as well as custom-defined REST action
methods.
For more on developing **RESTful** web applications with Pecan, see
:ref:`rest`.
'''
_custom_actions = {}
def __new__(cls, *args, **kwargs):
"""
RestController does not support the `route` argument to
:func:`~pecan.decorators.expose`
Implement this with __new__ rather than a metaclass, because it's very
common for pecan users to mixin RestController (with other bases that
have their own metaclasses).
"""
for name, value in getmembers(cls):
if iscontroller(value) and getattr(value, 'custom_route', None):
raise ValueError(
'Path segments cannot be used in combination with '
'pecan.rest.RestController. Remove the `route` argument '
'to @pecan.expose on %s.%s.%s' % (
cls.__module__, cls.__name__, value.__name__
)
)
# object.__new__ will error if called with extra arguments, and either
# __new__ is overridden or __init__ is not overridden;
# https://hg.python.org/cpython/file/78d36d54391c/Objects/typeobject.c#l3034
# In PY3, this is actually a TypeError (in PY2, it just raises
# a DeprecationWarning)
new = super(RestController, cls).__new__
if new is object.__new__:
return new(cls)
return new(cls, *args, **kwargs)
def _get_args_for_controller(self, controller):
"""
Retrieve the arguments we actually care about. For Pecan applications
that utilize thread locals, we should truncate the first argument,
`self`. For applications that explicitly pass request/response
references as the first controller arguments, we should truncate the
first three arguments, `self, req, resp`.
"""
argspec = getargspec(controller)
from pecan import request
try:
request.path
except AttributeError:
return argspec.args[3:]
return argspec.args[1:]
def _handle_bad_rest_arguments(self, controller, remainder, request):
"""
Ensure that the argspec for a discovered controller actually matched
the positional arguments in the request path. If not, raise
a webob.exc.HTTPBadRequest.
"""
argspec = self._get_args_for_controller(controller)
fixed_args = len(argspec) - len(
request.pecan.get('routing_args', [])
)
if len(remainder) < fixed_args:
# For controllers that are missing intermediate IDs
# (e.g., /authors/books vs /authors/1/books), return a 404 for an
# invalid path.
abort(404)
def _lookup_child(self, remainder):
"""
Lookup a child controller with a named path (handling Unicode paths
properly for Python 2).
"""
try:
controller = getattr(self, remainder, None)
except UnicodeEncodeError:
return None
return controller
@expose()
def _route(self, args, request=None):
'''
Routes a request to the appropriate controller and returns its result.
Performs a bit of validation - refuses to route delete and put actions
via a GET request).
'''
if request is None:
from pecan import request
# convention uses "_method" to handle browser-unsupported methods
method = request.params.get('_method', request.method).lower()
# make sure DELETE/PUT requests don't use GET
if request.method == 'GET' and method in ('delete', 'put'):
abort(405)
# check for nested controllers
result = self._find_sub_controllers(args, request)
if result:
return result
# handle the request
handler = getattr(
self,
'_handle_%s' % method,
self._handle_unknown_method
)
try:
if len(getargspec(handler).args) == 3:
result = handler(method, args)
else:
result = handler(method, args, request)
#
# If the signature of the handler does not match the number
# of remaining positional arguments, attempt to handle
# a _lookup method (if it exists)
#
argspec = self._get_args_for_controller(result[0])
num_args = len(argspec)
if num_args < len(args):
_lookup_result = self._handle_lookup(args, request)
if _lookup_result:
return _lookup_result
except (exc.HTTPClientError, exc.HTTPNotFound,
exc.HTTPMethodNotAllowed) as e:
#
# If the matching handler results in a 400, 404, or 405, attempt to
# handle a _lookup method (if it exists)
#
_lookup_result = self._handle_lookup(args, request)
if _lookup_result:
return _lookup_result
# Build a correct Allow: header
if isinstance(e, exc.HTTPMethodNotAllowed):
def method_iter():
for func in ('get', 'get_one', 'get_all', 'new', 'edit',
'get_delete'):
if self._find_controller(func):
yield 'GET'
break
for method in ('HEAD', 'POST', 'PUT', 'DELETE', 'TRACE',
'PATCH'):
func = method.lower()
if self._find_controller(func):
yield method
e.allow = sorted(method_iter())
raise
# return the result
return result
def _handle_lookup(self, args, request=None):
if request is None:
self._raise_method_deprecation_warning(self.handle_lookup)
# filter empty strings from the arg list
args = list(six.moves.filter(bool, args))
# check for lookup controllers
lookup = getattr(self, '_lookup', None)
if args and iscontroller(lookup):
result = handle_lookup_traversal(lookup, args)
if result:
obj, remainder = result
return lookup_controller(obj, remainder, request)
def _find_controller(self, *args):
'''
Returns the appropriate controller for routing a custom action.
'''
for name in args:
obj = self._lookup_child(name)
if obj and iscontroller(obj):
return obj
return None
def _find_sub_controllers(self, remainder, request):
'''
Identifies the correct controller to route to by analyzing the
request URI.
'''
# need either a get_one or get to parse args
method = None
for name in ('get_one', 'get'):
if hasattr(self, name):
method = name
break
if not method:
return
# get the args to figure out how much to chop off
args = self._get_args_for_controller(getattr(self, method))
fixed_args = len(args) - len(
request.pecan.get('routing_args', [])
)
var_args = getargspec(getattr(self, method)).varargs
# attempt to locate a sub-controller
if var_args:
for i, item in enumerate(remainder):
controller = self._lookup_child(item)
if controller and not ismethod(controller):
self._set_routing_args(request, remainder[:i])
return lookup_controller(controller, remainder[i + 1:],
request)
elif fixed_args < len(remainder) and hasattr(
self, remainder[fixed_args]
):
controller = self._lookup_child(remainder[fixed_args])
if not ismethod(controller):
self._set_routing_args(request, remainder[:fixed_args])
return lookup_controller(
controller,
remainder[fixed_args + 1:],
request
)
def _handle_unknown_method(self, method, remainder, request=None):
'''
Routes undefined actions (like RESET) to the appropriate controller.
'''
if request is None:
self._raise_method_deprecation_warning(self._handle_unknown_method)
# try finding a post_{custom} or {custom} method first
controller = self._find_controller('post_%s' % method, method)
if controller:
return controller, remainder
# if no controller exists, try routing to a sub-controller; note that
# since this isn't a safe GET verb, any local exposes are 405'd
if remainder:
if self._find_controller(remainder[0]):
abort(405)
sub_controller = self._lookup_child(remainder[0])
if sub_controller:
return lookup_controller(sub_controller, remainder[1:],
request)
abort(405)
def _handle_get(self, method, remainder, request=None):
'''
Routes ``GET`` actions to the appropriate controller.
'''
if request is None:
self._raise_method_deprecation_warning(self._handle_get)
# route to a get_all or get if no additional parts are available
if not remainder or remainder == ['']:
remainder = list(six.moves.filter(bool, remainder))
controller = self._find_controller('get_all', 'get')
if controller:
self._handle_bad_rest_arguments(controller, remainder, request)
return controller, []
abort(405)
method_name = remainder[-1]
# check for new/edit/delete GET requests
if method_name in ('new', 'edit', 'delete'):
if method_name == 'delete':
method_name = 'get_delete'
controller = self._find_controller(method_name)
if controller:
return controller, remainder[:-1]
match = self._handle_custom_action(method, remainder, request)
if match:
return match
controller = self._lookup_child(remainder[0])
if controller and not ismethod(controller):
return lookup_controller(controller, remainder[1:], request)
# finally, check for the regular get_one/get requests
controller = self._find_controller('get_one', 'get')
if controller:
self._handle_bad_rest_arguments(controller, remainder, request)
return controller, remainder
abort(405)
def _handle_delete(self, method, remainder, request=None):
'''
Routes ``DELETE`` actions to the appropriate controller.
'''
if request is None:
self._raise_method_deprecation_warning(self._handle_delete)
if remainder:
match = self._handle_custom_action(method, remainder, request)
if match:
return match
controller = self._lookup_child(remainder[0])
if controller and not ismethod(controller):
return lookup_controller(controller, remainder[1:], request)
# check for post_delete/delete requests first
controller = self._find_controller('post_delete', 'delete')
if controller:
return controller, remainder
# if no controller exists, try routing to a sub-controller; note that
# since this is a DELETE verb, any local exposes are 405'd
if remainder:
if self._find_controller(remainder[0]):
abort(405)
sub_controller = self._lookup_child(remainder[0])
if sub_controller:
return lookup_controller(sub_controller, remainder[1:],
request)
abort(405)
def _handle_post(self, method, remainder, request=None):
'''
Routes ``POST`` requests.
'''
if request is None:
self._raise_method_deprecation_warning(self._handle_post)
# check for custom POST/PUT requests
if remainder:
match = self._handle_custom_action(method, remainder, request)
if match:
return match
controller = self._lookup_child(remainder[0])
if controller and not ismethod(controller):
return lookup_controller(controller, remainder[1:], request)
# check for regular POST/PUT requests
controller = self._find_controller(method)
if controller:
return controller, remainder
abort(405)
def _handle_put(self, method, remainder, request=None):
return self._handle_post(method, remainder, request)
def _handle_custom_action(self, method, remainder, request=None):
if request is None:
self._raise_method_deprecation_warning(self._handle_custom_action)
remainder = [r for r in remainder if r]
if remainder:
if method in ('put', 'delete'):
# For PUT and DELETE, additional arguments are supplied, e.g.,
# DELETE /foo/XYZ
method_name = remainder[0]
remainder = remainder[1:]
else:
method_name = remainder[-1]
remainder = remainder[:-1]
if method.upper() in self._custom_actions.get(method_name, []):
controller = self._find_controller(
'%s_%s' % (method, method_name),
method_name
)
if controller:
return controller, remainder
def _set_routing_args(self, request, args):
'''
Sets default routing arguments.
'''
request.pecan.setdefault('routing_args', []).extend(args)
def _raise_method_deprecation_warning(self, handler):
warnings.warn(
(
"The function signature for %s.%s.%s is changing "
"in the next version of pecan.\nPlease update to: "
"`%s(self, method, remainder, request)`." % (
self.__class__.__module__,
self.__class__.__name__,
handler.__name__,
handler.__name__
)
),
DeprecationWarning
)
|