143 lines
4.8 KiB
Python
143 lines
4.8 KiB
Python
import warnings
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from inspect import getargspec
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from webob import exc
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from .secure import handle_security, cross_boundary
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from .util import iscontroller
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__all__ = ['lookup_controller', 'find_object']
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class PecanNotFound(Exception):
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pass
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class NonCanonicalPath(Exception):
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'''
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Exception Raised when a non-canonical path is encountered when 'walking'
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the URI. This is typically a ``POST`` request which requires a trailing
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slash.
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'''
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def __init__(self, controller, remainder):
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self.controller = controller
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self.remainder = remainder
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def lookup_controller(obj, remainder, request):
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'''
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Traverses the requested url path and returns the appropriate controller
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object, including default routes.
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Handles common errors gracefully.
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'''
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notfound_handlers = []
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while True:
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try:
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obj, remainder = find_object(obj, remainder, notfound_handlers,
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request)
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handle_security(obj)
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return obj, remainder
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except (exc.HTTPNotFound, PecanNotFound):
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while notfound_handlers:
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name, obj, remainder = notfound_handlers.pop()
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if name == '_default':
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# Notfound handler is, in fact, a controller, so stop
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# traversal
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return obj, remainder
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else:
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# Notfound handler is an internal redirect, so continue
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# traversal
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result = handle_lookup_traversal(obj, remainder)
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if result:
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# If no arguments are passed to the _lookup, yet the
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# argspec requires at least one, raise a 404
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if (
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remainder == ['']
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and len(obj._pecan['argspec'].args) > 1
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):
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raise exc.HTTPNotFound
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obj_, remainder_ = result
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return lookup_controller(obj_, remainder_, request)
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else:
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raise exc.HTTPNotFound
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def handle_lookup_traversal(obj, args):
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try:
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result = obj(*args)
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if result:
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prev_obj = obj
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obj, remainder = result
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# crossing controller boundary
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cross_boundary(prev_obj, obj)
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return result
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except TypeError as te:
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msg = 'Got exception calling lookup(): %s (%s)'
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warnings.warn(
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msg % (te, te.args),
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RuntimeWarning
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)
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def find_object(obj, remainder, notfound_handlers, request):
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'''
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'Walks' the url path in search of an action for which a controller is
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implemented and returns that controller object along with what's left
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of the remainder.
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'''
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prev_obj = None
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while True:
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if obj is None:
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raise PecanNotFound
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if iscontroller(obj):
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return obj, remainder
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# are we traversing to another controller
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cross_boundary(prev_obj, obj)
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try:
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next_obj, rest = remainder[0], remainder[1:]
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if next_obj == '':
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index = getattr(obj, 'index', None)
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if iscontroller(index):
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return index, rest
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except IndexError:
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# the URL has hit an index method without a trailing slash
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index = getattr(obj, 'index', None)
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if iscontroller(index):
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raise NonCanonicalPath(index, [])
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default = getattr(obj, '_default', None)
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if iscontroller(default):
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notfound_handlers.append(('_default', default, remainder))
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lookup = getattr(obj, '_lookup', None)
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if iscontroller(lookup):
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notfound_handlers.append(('_lookup', lookup, remainder))
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route = getattr(obj, '_route', None)
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if iscontroller(route):
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if len(getargspec(route).args) == 2:
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warnings.warn(
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(
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"The function signature for %s.%s._route is changing "
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"in the next version of pecan.\nPlease update to: "
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"`def _route(self, args, request)`." % (
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obj.__class__.__module__,
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obj.__class__.__name__
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)
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),
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DeprecationWarning
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)
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next_obj, next_remainder = route(remainder)
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else:
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next_obj, next_remainder = route(remainder, request)
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cross_boundary(route, next_obj)
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return next_obj, next_remainder
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if not remainder:
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raise PecanNotFound
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prev_obj = obj
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remainder = rest
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obj = getattr(obj, next_obj, None)
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