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# IVLE - Informatics Virtual Learning Environment
# Copyright (C) 2007-2009 The University of Melbourne
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
# Author: Matt Giuca, Will Grant, Nick Chadwick
import os
import cgi
import urlparse
import inspect
import cjson
import genshi.template
from ivle.webapp.base.views import BaseView
from ivle.webapp.errors import BadRequest, MethodNotAllowed, Unauthorized
class RESTView(BaseView):
"""
A view which provides a RESTful interface. The content type is
unspecified (see JSONRESTView for a specific content type).
"""
content_type = "application/octet-stream"
def __init__(self, req, *args, **kwargs):
for key in kwargs:
setattr(self, key, kwargs[key])
def render(self, req):
raise NotImplementedError()
class JSONRESTView(RESTView):
"""
A special case of RESTView which deals entirely in JSON.
"""
content_type = "application/json"
_allowed_methods = property(
lambda self: [m for m in ('GET', 'PUT', 'PATCH')
if hasattr(self, m)] + ['POST'])
def authorize(self, req):
return True # Real authz performed in render().
def authorize_method(self, req, op):
if not hasattr(op, '_rest_api_permission'):
raise Unauthorized()
if op._rest_api_permission not in self.get_permissions(req.user):
raise Unauthorized()
def convert_bool(self, value):
if value in ('True', 'true', True):
return True
elif value in ('False', 'false', False):
return False
else:
raise BadRequest()
def render(self, req):
if req.method not in self._allowed_methods:
raise MethodNotAllowed(allowed=self._allowed_methods)
if req.method == 'GET':
self.authorize_method(req, self.GET)
outjson = self.GET(req)
# Since PATCH isn't yet an official HTTP method, we allow users to
# turn a PUT into a PATCH by supplying a special header.
elif req.method == 'PATCH' or (req.method == 'PUT' and
'X-IVLE-Patch-Semantics' in req.headers_in and
req.headers_in['X-IVLE-Patch-Semantics'].lower() == 'yes'):
self.authorize_method(req, self.PATCH)
try:
input = cjson.decode(req.read())
except cjson.DecodeError:
raise BadRequest('Invalid JSON data')
outjson = self.PATCH(req, input)
elif req.method == 'PUT':
self.authorize_method(req, self.PUT)
try:
input = cjson.decode(req.read())
except cjson.DecodeError:
raise BadRequest('Invalid JSON data')
outjson = self.PUT(req, input)
# POST implies named operation.
elif req.method == 'POST':
# TODO: Check Content-Type and implement multipart/form-data.
data = req.read()
opargs = dict(cgi.parse_qsl(data, keep_blank_values=1))
try:
opname = opargs['ivle.op']
del opargs['ivle.op']
except KeyError:
raise BadRequest('No named operation specified.')
try:
op = getattr(self, opname)
except AttributeError:
raise BadRequest('Invalid named operation.')
if not hasattr(op, '_rest_api_callable') or \
not op._rest_api_callable:
raise BadRequest('Invalid named operation.')
self.authorize_method(req, op)
# Find any missing arguments, except for the first two (self, req)
(args, vaargs, varkw, defaults) = inspect.getargspec(op)
args = args[2:]
# To find missing arguments, we eliminate the provided arguments
# from the set of remaining function signature arguments. If the
# remaining signature arguments are in the args[-len(defaults):],
# we are OK.
unspec = set(args) - set(opargs.keys())
if unspec and not defaults:
raise BadRequest('Missing arguments: ' + ', '.join(unspec))
unspec = [k for k in unspec if k not in args[-len(defaults):]]
if unspec:
raise BadRequest('Missing arguments: ' + ', '.join(unspec))
# We have extra arguments if the are no match args in the function
# signature, AND there is no **.
extra = set(opargs.keys()) - set(args)
if extra and not varkw:
raise BadRequest('Extra arguments: ' + ', '.join(extra))
outjson = op(req, **opargs)
req.content_type = self.content_type
self.write_json(req, outjson)
#This is a separate function to allow additional data to be passed through
def write_json(self, req, outjson):
if outjson is not None:
req.write(cjson.encode(outjson))
req.write("\n")
class XHTMLRESTView(JSONRESTView):
"""A special type of RESTView which takes enhances the standard JSON
with genshi XHTML functions.
XHTMLRESTViews should have a template, which is rendered using their
context. This is returned in the JSON as 'html'"""
template = None
ctx = genshi.template.Context()
def __init__(self, req, *args, **kwargs):
for key in kwargs:
setattr(self, key, kwargs[key])
def render_fragment(self):
if self.template is None:
raise NotImplementedError()
rest_template = os.path.join(os.path.dirname(
inspect.getmodule(self).__file__), self.template)
loader = genshi.template.TemplateLoader(".", auto_reload=True)
tmpl = loader.load(rest_template)
return tmpl.generate(self.ctx).render('xhtml', doctype='xhtml')
# This renders the template and adds it to the json
def write_json(self, req, outjson):
outjson["html"] = self.render_fragment()
req.write(cjson.encode(outjson))
req.write("\n")
class named_operation(object):
'''Declare a function to be accessible to HTTP users via the REST API.
'''
def __init__(self, permission):
self.permission = permission
def __call__(self, func):
func._rest_api_callable = True
func._rest_api_permission = self.permission
return func
class require_permission(object):
'''Declare the permission required for use of a method via the REST API.
'''
def __init__(self, permission):
self.permission = permission
def __call__(self, func):
func._rest_api_permission = self.permission
return func
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