Files
deb-python-pecan/pecan/core.py
Jonathan LaCour 076814eea6 We now include autogenerated documentation for API from source code.
Starting with the pecan.core module.
2011-03-06 14:02:20 -05:00

522 lines
19 KiB
Python

from templating import RendererFactory
from routing import lookup_controller, NonCanonicalPath
from util import _cfg
from webob import Request, Response, exc
from threading import local
from itertools import chain
from formencode import htmlfill, Invalid, variabledecode
from formencode.schema import merge_dicts
from paste.recursive import ForwardRequestException
try:
from simplejson import loads
except ImportError: # pragma: no cover
from json import loads
import os
state = local()
def proxy(key):
class ObjectProxy(object):
def __getattr__(self, attr):
obj = getattr(state, key)
if attr == 'validation_errors':
return getattr(obj, attr, {})
return getattr(obj, attr)
def __setattr__(self, attr, value):
obj = getattr(state, key)
return setattr(obj, attr, value)
def __delattr__(self, attr):
obj = getattr(state, key)
return delattr(obj, attr)
return ObjectProxy()
request = proxy('request')
response = proxy('response')
def override_template(template, content_type=None):
'''
Call within a controller to override the template that is used in
your response.
:param template: a valid path to a template file, just as you would specify in an ``@expose``.
:param content_type: a valid MIME type to use for the response.
'''
request.override_template = template
if content_type:
request.override_content_type = content_type
def abort(status_code=None, detail='', headers=None, comment=None):
'''
Raise an HTTP status code, as specified. Useful for returning status
codes like 401 Unauthorized or 403 Forbidden.
:param status_code: The HTTP status code as an integer.
:param detail: The message to send along, as a string.
:param headers: A dictionary of headers to send along with the response.
:param comment: A comment to include in the response.
'''
raise exc.status_map[status_code](detail=detail, headers=headers, comment=comment)
def redirect(location, internal=False, code=None, headers={}):
'''
Perform a redirect, either internal or external. An internal redirect
performs the redirect server-side, while the external redirect utilizes
an HTTP 302 status code.
:param location: The HTTP location to redirect to.
:param internal: A boolean indicating whether the redirect should be internal.
:param code: The HTTP status code to use for the redirect. Defaults to 302.
:param headers: Any HTTP headers to send with the response, as a dictionary.
'''
if internal:
if code is not None:
raise ValueError('Cannot specify a code for internal redirects')
raise ForwardRequestException(location)
if code is None:
code = 302
raise exc.status_map[code](location=location, headers=getattr(response, 'headers', headers))
def error_for(field):
'''
A convenience function for fetching the validation error for a
particular field in a form. Useful within templates when not using
``htmlfill`` for forms.
:param field: The name of the field to get the error for.
'''
if not request.validation_errors:
return ''
return request.validation_errors.get(field, '')
def static(name, value):
'''
When using ``htmlfill`` validation support, this function indicates
that ``htmlfill`` should not fill in a value for this field, and
should instead use the value specified.
:param name: The name of the field.
:param value: The value to specify.
'''
if 'pecan.params' not in request.environ:
request.environ['pecan.params'] = dict(request.str_params)
request.environ['pecan.params'][name] = value
return value
def render(template, namespace):
'''
Render the specified template using the Pecan rendering framework
with the specified template namespace as a dictionary. Useful in a
controller where you have no template specified in the ``@expose``.
:param template: The path to your template, as you would specify in ``@expose``.
:param namespace: The namespace to use for rendering the template, as a dictionary.
'''
renderer = state.app.renderers.get(state.app.default_renderer, state.app.template_path)
if template == 'json':
renderer = state.app.renderers.get('json', state.app.template_path)
else:
namespace['error_for'] = error_for
namespace['static'] = static
if ':' in template:
renderer = state.app.renderers.get(template.split(':')[0], state.app.template_path)
template = template.split(':')[1]
return renderer.render(template, namespace)
class ValidationException(ForwardRequestException):
'''
This exception is raised when a validation error occurs using Pecan's
built-in validation framework.
'''
def __init__(self, location=None, errors={}):
if hasattr(state, 'controller'):
cfg = _cfg(state.controller)
else:
cfg = {}
if location is None and 'error_handler' in cfg:
location = cfg['error_handler']
if callable(location):
location = location()
merge_dicts(request.validation_errors, errors)
if 'pecan.params' not in request.environ:
request.environ['pecan.params'] = dict(request.str_params)
request.environ['pecan.validation_errors'] = request.validation_errors
if cfg.get('htmlfill') is not None:
request.environ['pecan.htmlfill'] = cfg['htmlfill']
request.environ['REQUEST_METHOD'] = 'GET'
ForwardRequestException.__init__(self, location)
class Pecan(object):
'''
Base Pecan application object. Generally created using ``pecan.make_app``,
rather than being created manually.
'''
def __init__(self, root,
default_renderer = 'mako',
template_path = 'templates',
hooks = [],
custom_renderers = {},
extra_template_vars = {},
force_canonical = True
):
'''
Creates a Pecan application instance, which is a WSGI application.
:param root: The root controller object.
:param default_renderer: The default rendering engine to use. Defaults to mako.
:param template_path: The default relative path to use for templates. Defaults to 'templates'.
:param hooks: A list of Pecan hook objects to use for this application.
:param custom_renderers: Custom renderer objects, as a dictionary keyed by engine name.
:param extra_template_vars: Any variables to inject into the template namespace automatically.
:param force_canonical: A boolean indicating if this project should require canonical URLs.
'''
self.root = root
self.renderers = RendererFactory(custom_renderers, extra_template_vars)
self.default_renderer = default_renderer
self.hooks = hooks
self.template_path = template_path
self.force_canonical = force_canonical
def get_content_type(self, format):
'''
Returns a content-type for a file extension.
:param format: The file extension, such as .html, .json, or .txt.
'''
return {
'.html' : 'text/html',
'.xhtml' : 'text/html',
'.json' : 'application/json',
'.txt' : 'text/plain'
}.get(format)
def route(self, node, path):
'''
Looks up a controller from a node based upon the specified path.
:param node: The node, such as a root controller object.
:param path: The path to look up on this node.
'''
path = path.split('/')[1:]
try:
node, remainder = lookup_controller(node, path)
return node, remainder
except NonCanonicalPath, e:
if self.force_canonical and not _cfg(e.controller).get('accept_noncanonical', False):
if request.method == 'POST':
raise RuntimeError, "You have POSTed to a URL '%s' which requires a slash. Most browsers will not maintain POST data when redirected. Please update your code to POST to '%s/' or set force_canonical to False" % (request.routing_path, request.routing_path)
raise exc.HTTPFound(add_slash=True)
return e.controller, e.remainder
def determine_hooks(self, controller=None):
'''
Determines the hooks to be run, in which order.
:param controller: If specified, includes hooks for a specific controller.
'''
controller_hooks = []
if controller:
controller_hooks = _cfg(controller).get('hooks', [])
return list(
sorted(
chain(controller_hooks, self.hooks),
lambda x,y: cmp(x.priority, y.priority)
)
)
def handle_hooks(self, hook_type, *args):
'''
Processes hooks of the specified type.
:param hook_type: The type of hook, including ``before``, ``after``, ``on_error``, and ``on_route``.
:param *args: Arguments to pass to the hooks.
'''
if hook_type in ['before', 'on_route']:
hooks = state.hooks
else:
hooks = reversed(state.hooks)
for hook in hooks:
getattr(hook, hook_type)(*args)
def get_args(self, all_params, remainder, argspec, im_self):
'''
Determines the arguments for a controller based upon parameters
passed the argument specification for the controller.
'''
args = []
kwargs = dict()
valid_args = argspec[0][1:]
if im_self is not None:
args.append(im_self)
# grab the routing args from nested REST controllers
if hasattr(request, 'routing_args'):
remainder = request.routing_args + list(remainder)
delattr(request, 'routing_args')
# handle positional arguments
if valid_args and remainder:
args.extend(remainder[:len(valid_args)])
remainder = remainder[len(valid_args):]
valid_args = valid_args[len(args):]
# handle wildcard arguments
if remainder:
if not argspec[1]:
abort(404)
args.extend(remainder)
# get the default positional arguments
if argspec[3]:
defaults = dict(zip(argspec[0][-len(argspec[3]):], argspec[3]))
else:
defaults = dict()
# handle positional GET/POST params
for name in valid_args:
if name in all_params:
args.append(all_params.pop(name))
elif name in defaults:
args.append(defaults[name])
else:
break
# handle wildcard GET/POST params
if argspec[2]:
for name, value in all_params.iteritems():
if name not in argspec[0]:
kwargs[name] = value
return args, kwargs
def validate(self, schema, params, json=False, error_handler=None,
htmlfill=None, variable_decode=None):
'''
Performs validation against a schema for any passed params,
including support for ``JSON``.
:param schema: A ``formencode`` ``Schema`` object to validate against.
:param params: The dictionary of parameters to validate.
:param json: A boolean, indicating whether or not the validation should validate against JSON content.
:param error_handler: The path to a controller which will handle errors. If not specified, validation errors will raise a ``ValidationException``.
:param htmlfill: Specifies whether or not to use htmlfill.
:param variable_decode: Indicates whether or not to decode variables when using htmlfill.
'''
request.validation_errors = {}
try:
to_validate = params
if json:
to_validate = loads(request.body)
if variable_decode is not None:
to_validate = variabledecode.variable_decode(to_validate, **variable_decode)
params = schema.to_python(to_validate)
except Invalid, e:
kwargs = {}
if variable_decode is not None:
kwargs['encode_variables'] = True
kwargs.update(variable_decode)
request.validation_errors = e.unpack_errors(**kwargs)
if error_handler is not None:
raise ValidationException()
if json:
params = dict(data=params)
return params
def handle_request(self):
'''
The main request handler for Pecan applications.
'''
# get a sorted list of hooks, by priority (no controller hooks yet)
state.hooks = self.determine_hooks()
# store the routing path to allow hooks to modify it
request.routing_path = request.path
# handle "on_route" hooks
self.handle_hooks('on_route', state)
# lookup the controller, respecting content-type as requested
# by the file extension on the URI
path = request.routing_path
if state.content_type is None and '.' in path.split('/')[-1]:
path, format = os.path.splitext(path)
# store the extension for retrieval by controllers
request.extension = format
state.content_type = self.get_content_type(format)
controller, remainder = self.route(self.root, path)
cfg = _cfg(controller)
if cfg.get('generic_handler'):
raise exc.HTTPNotFound
# handle generic controllers
im_self = None
if cfg.get('generic'):
im_self = controller.im_self
handlers = cfg['generic_handlers']
controller = handlers.get(request.method, handlers['DEFAULT'])
cfg = _cfg(controller)
# add the controller to the state so that hooks can use it
state.controller = controller
# if unsure ask the controller for the default content type
if state.content_type is None:
state.content_type = cfg.get('content_type', 'text/html')
# get a sorted list of hooks, by priority
state.hooks = self.determine_hooks(controller)
# handle "before" hooks
self.handle_hooks('before', state)
# fetch and validate any parameters
params = dict(request.str_params)
if 'schema' in cfg:
params = self.validate(
cfg['schema'],
params,
json=cfg['validate_json'],
error_handler=cfg.get('error_handler'),
htmlfill=cfg.get('htmlfill'),
variable_decode=cfg.get('variable_decode')
)
elif 'pecan.validation_errors' in request.environ:
request.validation_errors = request.environ.pop('pecan.validation_errors')
# fetch the arguments for the controller
args, kwargs = self.get_args(
params,
remainder,
cfg['argspec'],
im_self
)
# get the result from the controller
result = controller(*args, **kwargs)
# a controller can return the response object which means they've taken
# care of filling it out
if result == response:
return
raw_namespace = result
# pull the template out based upon content type and handle overrides
template = cfg.get('content_types', {}).get(state.content_type)
# check if for controller override of template
template = getattr(request, 'override_template', template)
state.content_type = getattr(request, 'override_content_type', state.content_type)
# if there is a template, render it
if template:
if template == 'json':
state.content_type = self.get_content_type('.json')
result = render(template, result)
# pass the response through htmlfill (items are popped out of the
# environment even if htmlfill won't run for proper cleanup)
_htmlfill = cfg.get('htmlfill')
if _htmlfill is None and 'pecan.htmlfill' in request.environ:
_htmlfill = request.environ.pop('pecan.htmlfill')
if 'pecan.params' in request.environ:
params = request.environ.pop('pecan.params')
if request.validation_errors and _htmlfill is not None and state.content_type == 'text/html':
errors = getattr(request, 'validation_errors', {})
result = htmlfill.render(result, defaults=params, errors=errors, **_htmlfill)
# If we are in a test request put the namespace where it can be
# accessed directly
if request.environ.get('paste.testing'):
testing_variables = request.environ['paste.testing_variables']
testing_variables['namespace'] = raw_namespace
testing_variables['template_name'] = template
testing_variables['controller_output'] = result
# set the body content
if isinstance(result, unicode):
response.unicode_body = result
else:
response.body = result
# set the content type
if state.content_type:
response.content_type = state.content_type
def __call__(self, environ, start_response):
'''
Implements the WSGI specification for Pecan applications, utilizing ``WebOb``.
'''
# create the request and response object
state.request = Request(environ)
state.content_type = None
state.response = Response()
state.hooks = []
state.app = self
# handle the request
try:
# add context to the request
state.request.context = {}
self.handle_request()
except Exception, e:
# if this is an HTTP Exception, set it as the response
if isinstance(e, exc.HTTPException):
state.response = e
# if this is not an internal redirect, run error hooks
if not isinstance(e, ForwardRequestException):
self.handle_hooks('on_error', state, e)
if not isinstance(e, exc.HTTPException):
raise
finally:
# handle "after" hooks
self.handle_hooks('after', state)
# get the response
try:
return state.response(environ, start_response)
finally:
# clean up state
del state.content_type
del state.hooks
del state.request
del state.response
if hasattr(state, 'controller'):
del state.controller