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# Copyright 2008-2018 Canonical Ltd. All rights reserved.
# This file is part of wadllib.
#
# wadllib is free software: you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation, version 3 of the License.
#
# wadllib 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 Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with wadllib. If not, see <http://www.gnu.org/licenses/>.
"""Navigate the resources exposed by a web service.
The wadllib library helps a web client navigate the resources
exposed by a web service. The service defines its resources in a
single WADL file. wadllib parses this file and gives access to the
resources defined inside. The client code can see the capabilities of
a given resource and make the corresponding HTTP requests.
If a request returns a representation of the resource, the client can
bind the string representation to the wadllib Resource object.
"""
__metaclass__ = type
__all__ = [
'Application',
'Link',
'Method',
'NoBoundRepresentationError',
'Parameter',
'RepresentationDefinition',
'ResponseDefinition',
'Resource',
'ResourceType',
'WADLError',
]
import datetime
from email.utils import quote
import io
import json
import random
import re
import sys
import time
try:
from urllib.parse import urlencode
except ImportError:
from urllib import urlencode
try:
import xml.etree.cElementTree as ET
except ImportError:
import xml.etree.ElementTree as ET
from lazr.uri import URI, merge
from wadllib import (
_make_unicode,
_string_types,
)
from wadllib.iso_strptime import iso_strptime
NS_MAP = "xmlns:map"
XML_SCHEMA_NS_URI = 'http://www.w3.org/2001/XMLSchema'
def wadl_tag(tag_name):
"""Scope a tag name with the WADL namespace."""
return '{http://research.sun.com/wadl/2006/10}' + tag_name
def wadl_xpath(tag_name):
"""Turn a tag name into an XPath path."""
return './' + wadl_tag(tag_name)
def _merge_dicts(*dicts):
"""Merge any number of dictionaries, some of which may be None."""
final = {}
for dict in dicts:
if dict is not None:
final.update(dict)
return final
class WADLError(Exception):
"""An exception having to do with the state of the WADL application."""
pass
class NoBoundRepresentationError(WADLError):
"""An unbound resource was used where wadllib expected a bound resource.
To obtain the value of a resource's parameter, you first must bind
the resource to a representation. Otherwise the resource has no
idea what the value is and doesn't even know if you've given it a
parameter name that makes sense.
"""
class UnsupportedMediaTypeError(WADLError):
"""A media type was given that's not supported in this context.
A resource can only be bound to media types it has representations
of.
"""
class WADLBase(object):
"""A base class for objects that contain WADL-derived information."""
class HasParametersMixin:
"""A mixin class for objects that have associated Parameter objects."""
def params(self, styles, resource=None):
"""Find subsidiary parameters that have the given styles."""
if resource is None:
resource = self.resource
if resource is None:
raise ValueError("Could not find any particular resource")
if self.tag is None:
return []
param_tags = self.tag.findall(wadl_xpath('param'))
if param_tags is None:
return []
return [Parameter(resource, param_tag)
for param_tag in param_tags
if param_tag.attrib.get('style') in styles]
def validate_param_values(self, params, param_values,
enforce_completeness=True, **kw_param_values):
"""Make sure the given valueset is valid.
A valueset might be invalid because it contradicts a fixed
value or (if enforce_completeness is True) because it lacks a
required value.
:param params: A list of Parameter objects.
:param param_values: A dictionary of parameter values. May include
paramters whose names are not valid Python identifiers.
:param enforce_completeness: If True, this method will raise
an exception when the given value set lacks a value for a
required parameter.
:param kw_param_values: A dictionary of parameter values.
:return: A dictionary of validated parameter values.
"""
param_values = _merge_dicts(param_values, kw_param_values)
validated_values = {}
for param in params:
name = param.name
if param.fixed_value is not None:
if (name in param_values
and param_values[name] != param.fixed_value):
raise ValueError(("Value '%s' for parameter '%s' "
"conflicts with fixed value '%s'")
% (param_values[name], name,
param.fixed_value))
param_values[name] = param.fixed_value
options = [option.value for option in param.options]
if (len(options) > 0 and name in param_values
and param_values[name] not in options):
raise ValueError(("Invalid value '%s' for parameter '%s': "
'valid values are: "%s"') % (
param_values[name], name, '", "'.join(options)))
if (enforce_completeness and param.is_required
and not name in param_values):
raise ValueError("No value for required parameter '%s'"
% name)
if name in param_values:
validated_values[name] = param_values[name]
del param_values[name]
if len(param_values) > 0:
raise ValueError("Unrecognized parameter(s): '%s'"
% "', '".join(param_values.keys()))
return validated_values
class WADLResolvableDefinition(WADLBase):
"""A base class for objects whose definitions may be references."""
def __init__(self, application):
"""Initialize with a WADL application.
:param application: A WADLDefinition. Relative links are
assumed to be relative to this object's URL.
"""
self._definition = None
self.application = application
def resolve_definition(self):
"""Return the definition of this object, wherever it is.
Resource is a good example. A WADL <resource> tag
may contain a large number of nested tags describing a
resource, or it may just contain a 'type' attribute that
references a <resource_type> which contains those same
tags. Resource.resolve_definition() will return the original
Resource object in the first case, and a
ResourceType object in the second case.
"""
if self._definition is not None:
return self._definition
object_url = self._get_definition_url()
if object_url is None:
# The object contains its own definition.
# XXX leonardr 2008-05-28:
# This code path is not tested in Launchpad.
self._definition = self
return self
# The object makes reference to some other object. Resolve
# its URL and return it.
xml_id = self.application.lookup_xml_id(object_url)
definition = self._definition_factory(xml_id)
if definition is None:
# XXX leonardr 2008-06-
# This code path is not tested in Launchpad.
# It requires an invalid WADL file that makes
# a reference to a nonexistent tag within the
# same WADL file.
raise KeyError('No such XML ID: "%s"' % object_url)
self._definition = definition
return definition
def _definition_factory(self, id):
"""Transform an XML ID into a wadllib wrapper object.
Which kind of object it is depends on the subclass.
"""
raise NotImplementedError()
def _get_definition_url(self):
"""Find the URL that identifies an external reference.
How to do this depends on the subclass.
"""
raise NotImplementedError()
class Resource(WADLResolvableDefinition):
"""A resource, possibly bound to a representation."""
def __init__(self, application, url, resource_type,
representation=None, media_type=None,
representation_needs_processing=True,
representation_definition=None):
"""
:param application: A WADLApplication.
:param url: The URL to this resource.
:param resource_type: An ElementTree <resource> or <resource_type> tag.
:param representation: A string representation.
:param media_type: The media type of the representation.
:param representation_needs_processing: Set to False if the
'representation' parameter should be used as
is. Otherwise, it will be transformed from a string into
an appropriate Python data structure, depending on its
media type.
:param representation_definition: A RepresentationDefinition
object describing the structure of this
representation. Used in cases when the representation
isn't the result of sending a standard GET to the
resource.
"""
super(Resource, self).__init__(application)
self._url = url
if isinstance(resource_type, _string_types):
# We were passed the URL to a resource type. Look up the
# type object itself
self.tag = self.application.get_resource_type(resource_type).tag
else:
# We were passed an XML tag that describes a resource or
# resource type.
self.tag = resource_type
self.representation = None
if representation is not None:
if media_type == 'application/json':
if representation_needs_processing:
self.representation = json.loads(
_make_unicode(representation))
else:
self.representation = representation
else:
raise UnsupportedMediaTypeError(
"This resource doesn't define a representation for "
"media type %s" % media_type)
self.media_type = media_type
if representation is not None:
if representation_definition is not None:
self.representation_definition = representation_definition
else:
self.representation_definition = (
self.get_representation_definition(self.media_type))
@property
def url(self):
"""Return the URL to this resource."""
return self._url
@property
def type_url(self):
"""Return the URL to the type definition for this resource, if any."""
if self.tag is None:
return None
url = self.tag.attrib.get('type')
if url is not None:
# This resource is defined in the WADL file.
return url
type_id = self.tag.attrib.get('id')
if type_id is not None:
# This resource was obtained by following a link.
base = URI(self.application.markup_url).ensureSlash()
return str(base) + '#' + type_id
# This resource does not have any associated resource type.
return None
@property
def id(self):
"""Return the ID of this resource."""
return self.tag.attrib['id']
def bind(self, representation, media_type='application/json',
representation_needs_processing=True,
representation_definition=None):
"""Bind the resource to a representation of that resource.
:param representation: A string representation
:param media_type: The media type of the representation.
:param representation_needs_processing: Set to False if the
'representation' parameter should be used as
is.
:param representation_definition: A RepresentationDefinition
object describing the structure of this
representation. Used in cases when the representation
isn't the result of sending a standard GET to the
resource.
:return: A Resource bound to a particular representation.
"""
return Resource(self.application, self.url, self.tag,
representation, media_type,
representation_needs_processing,
representation_definition)
def get_representation_definition(self, media_type):
"""Get a description of one of this resource's representations."""
default_get_response = self.get_method('GET').response
for representation in default_get_response:
representation_tag = representation.resolve_definition().tag
if representation_tag.attrib.get('mediaType') == media_type:
return representation
raise UnsupportedMediaTypeError("No definition for representation "
"with media type %s." % media_type)
def get_method(self, http_method=None, media_type=None, query_params=None,
representation_params=None):
"""Look up one of this resource's methods by HTTP method.
:param http_method: The HTTP method used to invoke the desired
method. Case-insensitive and optional.
:param media_type: The media type of the representation
accepted by the method. Optional.
:param query_params: The names and values of any fixed query
parameters used to distinguish between
two methods that use the same HTTP
method. Optional.
:param representation_params: The names and values of any
fixed representation parameters used to
distinguish between two methods that use
the same HTTP method and have the same
media type. Optional.
:return: A MethodDefinition, or None if there's no definition
that fits the given constraints.
"""
for method_tag in self._method_tag_iter():
name = method_tag.attrib.get('name', '').lower()
if http_method is None or name == http_method.lower():
method = Method(self, method_tag)
if method.is_described_by(media_type, query_params,
representation_params):
return method
return None
def parameters(self, media_type=None):
"""A list of this resource's parameters.
:param media_type: Media type of the representation definition
whose parameters are being named. Must be present unless
this resource is bound to a representation.
:raise NoBoundRepresentationError: If this resource is not
bound to a representation and media_type was not provided.
"""
return self._find_representation_definition(
media_type).params(self)
def parameter_names(self, media_type=None):
"""A list naming this resource's parameters.
:param media_type: Media type of the representation definition
whose parameters are being named. Must be present unless
this resource is bound to a representation.
:raise NoBoundRepresentationError: If this resource is not
bound to a representation and media_type was not provided.
"""
return self._find_representation_definition(
media_type).parameter_names(self)
@property
def method_iter(self):
"""An iterator over the methods defined on this resource."""
for method_tag in self._method_tag_iter():
yield Method(self, method_tag)
def get_parameter(self, param_name, media_type=None):
"""Find a parameter within a representation definition.
:param param_name: Name of the parameter to find.
:param media_type: Media type of the representation definition
whose parameters are being named. Must be present unless
this resource is bound to a representation.
:raise NoBoundRepresentationError: If this resource is not
bound to a representation and media_type was not provided.
"""
definition = self._find_representation_definition(media_type)
representation_tag = definition.tag
for param_tag in representation_tag.findall(wadl_xpath('param')):
if param_tag.attrib.get('name') == param_name:
return Parameter(self, param_tag)
return None
def get_parameter_value(self, parameter):
"""Find the value of a parameter, given the Parameter object.
:raise ValueError: If the parameter value can't be converted into
its defined type.
"""
if self.representation is None:
raise NoBoundRepresentationError(
"Resource is not bound to any representation.")
if self.media_type == 'application/json':
# XXX leonardr 2008-05-28 A real JSONPath implementation
# should go here. It should execute tag.attrib['path']
# against the JSON representation.
#
# Right now the implementation assumes the JSON
# representation is a hash and treats tag.attrib['name'] as a
# key into the hash.
if parameter.style != 'plain':
raise NotImplementedError(
"Don't know how to find value for a parameter of "
"type %s." % parameter.style)
value = self.representation[parameter.name]
if value is not None:
namespace_url, data_type = self._dereference_namespace(
parameter.tag, parameter.type)
if (namespace_url == XML_SCHEMA_NS_URI
and data_type in ['dateTime', 'date']):
try:
# Parse it as an ISO 8601 date and time.
value = iso_strptime(value)
except ValueError:
# Parse it as an ISO 8601 date.
try:
value = datetime.datetime(
*(time.strptime(value, "%Y-%m-%d")[0:6]))
except ValueError:
# Raise an unadorned ValueError so the client
# can treat the value as a string if they
# want.
raise ValueError(value)
return value
raise NotImplementedError("Path traversal not implemented for "
"a representation of media type %s."
% self.media_type)
def _dereference_namespace(self, tag, value):
"""Splits a value into namespace URI and value.
:param tag: A tag to use as context when mapping namespace
names to URIs.
"""
if value is not None and ':' in value:
namespace, value = value.split(':', 1)
else:
namespace = ''
ns_map = tag.get(NS_MAP)
namespace_url = ns_map.get(namespace, None)
return namespace_url, value
def _definition_factory(self, id):
"""Given an ID, find a ResourceType for that ID."""
return self.application.resource_types.get(id)
def _get_definition_url(self):
"""Return the URL that shows where a resource is 'really' defined.
If a resource's capabilities are defined by reference, the
<resource> tag's 'type' attribute will contain the URL to the
<resource_type> that defines them.
"""
return self.tag.attrib.get('type')
def _find_representation_definition(self, media_type=None):
"""Get the most appropriate representation definition.
If media_type is provided, the most appropriate definition is
the definition of the representation of that media type.
If this resource is bound to a representation, the most
appropriate definition is the definition of that
representation. Otherwise, the most appropriate definition is
the definition of the representation served in response to a
standard GET.
:param media_type: Media type of the definition to find. Must
be present unless the resource is bound to a
representation.
:raise NoBoundRepresentationError: If this resource is not
bound to a representation and media_type was not provided.
:return: A RepresentationDefinition
"""
if self.representation is not None:
# We know that when this object was created, a
# representation definition was either looked up, or
# directly passed in along with the representation.
definition = self.representation_definition.resolve_definition()
elif media_type is not None:
definition = self.get_representation_definition(media_type)
else:
raise NoBoundRepresentationError(
"Resource is not bound to any representation, and no media "
"media type was specified.")
return definition.resolve_definition()
def _method_tag_iter(self):
"""Iterate over this resource's <method> tags."""
definition = self.resolve_definition().tag
for method_tag in definition.findall(wadl_xpath('method')):
yield method_tag
class Method(WADLBase):
"""A wrapper around an XML <method> tag.
"""
def __init__(self, resource, method_tag):
"""Initialize with a <method> tag.
:param method_tag: An ElementTree <method> tag.
"""
self.resource = resource
self.application = self.resource.application
self.tag = method_tag
@property
def request(self):
"""Return the definition of a request that invokes the WADL method."""
return RequestDefinition(self, self.tag.find(wadl_xpath('request')))
@property
def response(self):
"""Return the definition of the response to the WADL method."""
return ResponseDefinition(self.resource,
self.tag.find(wadl_xpath('response')))
@property
def id(self):
"""The XML ID of the WADL method definition."""
return self.tag.attrib.get('id')
@property
def name(self):
"""The name of the WADL method definition.
This is also the name of the HTTP method (GET, POST, etc.)
that should be used to invoke the WADL method.
"""
return self.tag.attrib.get('name').lower()
def build_request_url(self, param_values=None, **kw_param_values):
"""Return the request URL to use to invoke this method."""
return self.request.build_url(param_values, **kw_param_values)
def build_representation(self, media_type=None,
param_values=None, **kw_param_values):
"""Build a representation to be sent when invoking this method.
:return: A 2-tuple of (media_type, representation).
"""
return self.request.representation(
media_type, param_values, **kw_param_values)
def is_described_by(self, media_type=None, query_values=None,
representation_values=None):
"""Returns true if this method fits the given constraints.
:param media_type: The method must accept this media type as a
representation.
:param query_values: These key-value pairs must be acceptable
as values for this method's query
parameters. This need not be a complete set
of parameters acceptable to the method.
:param representation_values: These key-value pairs must be
acceptable as values for this method's
representation parameters. Again, this need
not be a complete set of parameters
acceptable to the method.
"""
representation = None
if media_type is not None:
representation = self.request.get_representation_definition(
media_type)
if representation is None:
return False
if query_values is not None and len(query_values) > 0:
request = self.request
if request is None:
# This method takes no special request
# parameters, so it can't match.
return False
try:
request.validate_param_values(
request.query_params, query_values, False)
except ValueError:
return False
# At this point we know the media type and query values match.
if (representation_values is None
or len(representation_values) == 0):
return True
if representation is not None:
return representation.is_described_by(
representation_values)
for representation in self.request.representations:
try:
representation.validate_param_values(
representation.params(self.resource),
representation_values, False)
return True
except ValueError:
pass
return False
class RequestDefinition(WADLBase, HasParametersMixin):
"""A wrapper around the description of the request invoking a method."""
def __init__(self, method, request_tag):
"""Initialize with a <request> tag.
:param resource: The resource to which this request can be sent.
:param request_tag: An ElementTree <request> tag.
"""
self.method = method
self.resource = self.method.resource
self.application = self.resource.application
self.tag = request_tag
@property
def query_params(self):
"""Return the query parameters for this method."""
return self.params(['query'])
@property
def representations(self):
for definition in self.tag.findall(wadl_xpath('representation')):
yield RepresentationDefinition(
self.application, self.resource, definition)
def get_representation_definition(self, media_type=None):
"""Return the appropriate representation definition."""
for representation in self.representations:
if media_type is None or representation.media_type == media_type:
return representation
return None
def representation(self, media_type=None, param_values=None,
**kw_param_values):
"""Build a representation to be sent along with this request.
:return: A 2-tuple of (media_type, representation).
"""
definition = self.get_representation_definition(media_type)
if definition is None:
raise TypeError("Cannot build representation of media type %s"
% media_type)
return definition.bind(param_values, **kw_param_values)
def build_url(self, param_values=None, **kw_param_values):
"""Return the request URL to use to invoke this method."""
validated_values = self.validate_param_values(
self.query_params, param_values, **kw_param_values)
url = self.resource.url
if len(validated_values) > 0:
if '?' in url:
append = '&'
else:
append = '?'
url += append + urlencode(sorted(validated_values.items()))
return url
class ResponseDefinition(HasParametersMixin):
"""A wrapper around the description of a response to a method."""
# XXX leonardr 2008-05-29 it would be nice to have
# ResponseDefinitions for POST operations and nonstandard GET
# operations say what representations and/or status codes you get
# back. Getting this to work with Launchpad requires work on the
# Launchpad side.
def __init__(self, resource, response_tag, headers=None):
"""Initialize with a <response> tag.
:param response_tag: An ElementTree <response> tag.
"""
self.application = resource.application
self.resource = resource
self.tag = response_tag
self.headers = headers
def __iter__(self):
"""Get an iterator over the representation definitions.
These are the representations returned in response to an
invocation of this method.
"""
path = wadl_xpath('representation')
for representation_tag in self.tag.findall(path):
yield RepresentationDefinition(
self.resource.application, self.resource, representation_tag)
def bind(self, headers):
"""Bind the response to a set of HTTP headers.
A WADL response can have associated header parameters, but no
other kind.
"""
return ResponseDefinition(self.resource, self.tag, headers)
def get_parameter(self, param_name):
"""Find a header parameter within the response."""
for param_tag in self.tag.findall(wadl_xpath('param')):
if (param_tag.attrib.get('name') == param_name
and param_tag.attrib.get('style') == 'header'):
return Parameter(self, param_tag)
return None
def get_parameter_value(self, parameter):
"""Find the value of a parameter, given the Parameter object."""
if self.headers is None:
raise NoBoundRepresentationError(
"Response object is not bound to any headers.")
if parameter.style != 'header':
raise NotImplementedError(
"Don't know how to find value for a parameter of "
"type %s." % parameter.style)
return self.headers.get(parameter.name)
def get_representation_definition(self, media_type):
"""Get one of the possible representations of the response."""
if self.tag is None:
return None
for representation in self:
if representation.media_type == media_type:
return representation
return None
class RepresentationDefinition(WADLResolvableDefinition, HasParametersMixin):
"""A definition of the structure of a representation."""
def __init__(self, application, resource, representation_tag):
super(RepresentationDefinition, self).__init__(application)
self.resource = resource
self.tag = representation_tag
def params(self, resource):
return super(RepresentationDefinition, self).params(
['query', 'plain'], resource)
def parameter_names(self, resource):
"""Return the names of all parameters."""
return [param.name for param in self.params(resource)]
@property
def media_type(self):
"""The media type of the representation described here."""
return self.resolve_definition().tag.attrib['mediaType']
def _make_boundary(self, all_parts):
"""Make a random boundary that does not appear in `all_parts`."""
_width = len(repr(sys.maxsize - 1))
_fmt = '%%0%dd' % _width
token = random.randrange(sys.maxsize)
boundary = ('=' * 15) + (_fmt % token) + '=='
if all_parts is None:
return boundary
b = boundary
counter = 0
while True:
pattern = ('^--' + re.escape(b) + '(--)?$').encode('ascii')
if not re.search(pattern, all_parts, flags=re.MULTILINE):
break
b = boundary + '.' + str(counter)
counter += 1
return b
def _write_headers(self, buf, headers):
"""Write MIME headers to a file object."""
for key, value in headers:
buf.write(key.encode('UTF-8'))
buf.write(b': ')
buf.write(value.encode('UTF-8'))
buf.write(b'\r\n')
buf.write(b'\r\n')
def _write_boundary(self, buf, boundary, closing=False):
"""Write a multipart boundary to a file object."""
buf.write(b'--')
buf.write(boundary.encode('UTF-8'))
if closing:
buf.write(b'--')
buf.write(b'\r\n')
def _generate_multipart_form(self, parts):
"""Generate a multipart/form-data message.
This is very loosely based on the email module in the Python standard
library. However, that module doesn't really support directly embedding
binary data in a form: various versions of Python have mangled line
separators in different ways, and none of them get it quite right.
Since we only need a tiny subset of MIME here, it's easier to implement
it ourselves.
:return: a tuple of two elements: the Content-Type of the message, and
the entire encoded message as a byte string.
"""
# Generate the subparts first so that we can calculate a safe boundary.
encoded_parts = []
for is_binary, name, value in parts:
buf = io.BytesIO()
if is_binary:
ctype = 'application/octet-stream'
# RFC 7578 says that the filename parameter isn't mandatory
# in our case, but without it cgi.FieldStorage tries to
# decode as text on Python 3.
cdisp = 'form-data; name="%s"; filename="%s"' % (
quote(name), quote(name))
else:
ctype = 'text/plain; charset="utf-8"'
cdisp = 'form-data; name="%s"' % quote(name)
self._write_headers(buf, [
('MIME-Version', '1.0'),
('Content-Type', ctype),
('Content-Disposition', cdisp),
])
if is_binary:
if not isinstance(value, bytes):
raise TypeError('bytes payload expected: %s' % type(value))
buf.write(value)
else:
if not isinstance(value, _string_types):
raise TypeError(
'string payload expected: %s' % type(value))
lines = re.split(r'\r\n|\r|\n', value)
for line in lines[:-1]:
buf.write(line.encode('UTF-8'))
buf.write(b'\r\n')
buf.write(lines[-1].encode('UTF-8'))
encoded_parts.append(buf.getvalue())
# Create a suitable boundary.
boundary = self._make_boundary(b'\r\n'.join(encoded_parts))
# Now we can write the multipart headers, followed by all the parts.
buf = io.BytesIO()
ctype = 'multipart/form-data; boundary="%s"' % quote(boundary)
self._write_headers(buf, [
('MIME-Version', '1.0'),
('Content-Type', ctype),
])
for encoded_part in encoded_parts:
self._write_boundary(buf, boundary)
buf.write(encoded_part)
buf.write(b'\r\n')
self._write_boundary(buf, boundary, closing=True)
return ctype, buf.getvalue()
def bind(self, param_values, **kw_param_values):
"""Bind the definition to parameter values, creating a document.
:return: A 2-tuple (media_type, document).
"""
definition = self.resolve_definition()
params = definition.params(self.resource)
validated_values = self.validate_param_values(
params, param_values, **kw_param_values)
media_type = self.media_type
if media_type == 'application/x-www-form-urlencoded':
doc = urlencode(sorted(validated_values.items()))
elif media_type == 'multipart/form-data':
parts = []
missing = object()
for param in params:
value = validated_values.get(param.name, missing)
if value is not missing:
parts.append((param.type == 'binary', param.name, value))
media_type, doc = self._generate_multipart_form(parts)
elif media_type == 'application/json':
doc = json.dumps(validated_values)
else:
raise ValueError("Unsupported media type: '%s'" % media_type)
return media_type, doc
def _definition_factory(self, id):
"""Turn a representation ID into a RepresentationDefinition."""
return self.application.representation_definitions.get(id)
def _get_definition_url(self):
"""Find the URL containing the representation's 'real' definition.
If a representation's structure is defined by reference, the
<representation> tag's 'href' attribute will contain the URL
to the <representation> that defines the structure.
"""
return self.tag.attrib.get('href')
class Parameter(WADLBase):
"""One of the parameters of a representation definition."""
def __init__(self, value_container, tag):
"""Initialize with respect to a value container.
:param value_container: Usually the resource whose representation
has this parameter. If the resource is bound to a representation,
you'll be able to find the value of this parameter in the
representation. This may also be a server response whose headers
define a value for this parameter.
:tag: The ElementTree <param> tag for this parameter.
"""
self.application = value_container.application
self.value_container = value_container
self.tag = tag
@property
def name(self):
"""The name of this parameter."""
return self.tag.attrib.get('name')
@property
def style(self):
"""The style of this parameter."""
return self.tag.attrib.get('style')
@property
def type(self):
"""The XSD type of this parameter."""
return self.tag.attrib.get('type')
@property
def fixed_value(self):
"""The value to which this parameter is fixed, if any.
A fixed parameter must be present in invocations of a WADL
method, and it must have a particular value. This is commonly
used to designate one parameter as containing the name of the
server-side operation to be invoked.
"""
return self.tag.attrib.get('fixed')
@property
def is_required(self):
"""Whether or not a value for this parameter is required."""
return (self.tag.attrib.get('required', 'false').lower()
in ['1', 'true'])
def get_value(self):
"""The value of this parameter in the bound representation/headers.
:raise NoBoundRepresentationError: If this parameter's value
container is not bound to a representation or a set of
headers.
"""
return self.value_container.get_parameter_value(self)
@property
def options(self):
"""Return the set of acceptable values for this parameter."""
return [Option(self, option_tag)
for option_tag in self.tag.findall(wadl_xpath('option'))]
@property
def link(self):
"""Get the link to another resource.
The link may be examined and, if its type is of a known WADL
description, it may be followed.
:return: A Link object, or None.
"""
link_tag = self.tag.find(wadl_xpath('link'))
if link_tag is None:
return None
return Link(self, link_tag)
@property
def linked_resource(self):
"""Follow a link from this parameter to a new resource.
This only works for parameters whose WADL definition includes a
<link> tag that points to a known WADL description.
:return: A Resource object for the resource at the other end
of the link.
"""
link = self.link
if link is None:
raise ValueError("This parameter isn't a link to anything.")
return link.follow
class Option(WADLBase):
"""One of a set of possible values for a parameter."""
def __init__(self, parameter, option_tag):
"""Initialize the option.
:param parameter: A Parameter.
:param link_tag: An ElementTree <option> tag.
"""
self.parameter = parameter
self.tag = option_tag
@property
def value(self):
return self.tag.attrib.get('value')
class Link(WADLResolvableDefinition):
"""A link from one resource to another.
Calling resolve_definition() on a Link will give you a Resource for the
type of resource linked to. An alias for this is 'follow'.
"""
def __init__(self, parameter, link_tag):
"""Initialize the link.
:param parameter: A Parameter.
:param link_tag: An ElementTree <link> tag.
"""
super(Link, self).__init__(parameter.application)
self.parameter = parameter
self.tag = link_tag
@property
def follow(self):
"""Follow the link to another Resource."""
if not self.can_follow:
raise WADLError("Cannot follow a link when the target has no "
"WADL description. Try using a general HTTP "
"client instead.")
return self.resolve_definition()
@property
def can_follow(self):
"""Can this link be followed within wadllib?
wadllib can follow a link if it points to a resource that has
a WADL definition.
"""
try:
definition_url = self._get_definition_url()
except WADLError:
return False
return True
def _definition_factory(self, id):
"""Turn a resource type ID into a ResourceType."""
return Resource(
self.application, self.parameter.get_value(),
self.application.resource_types.get(id).tag)
def _get_definition_url(self):
"""Find the URL containing the definition ."""
type = self.tag.attrib.get('resource_type')
if type is None:
raise WADLError("Parameter is a link, but not to a resource "
"with a known WADL description.")
return type
class ResourceType(WADLBase):
"""A wrapper around an XML <resource_type> tag."""
def __init__(self, resource_type_tag):
"""Initialize with a <resource_type> tag.
:param resource_type_tag: An ElementTree <resource_type> tag.
"""
self.tag = resource_type_tag
class Application(WADLBase):
"""A WADL document made programmatically accessible."""
def __init__(self, markup_url, markup):
"""Parse WADL and find the most important parts of the document.
:param markup_url: The URL from which this document was obtained.
:param markup: The WADL markup itself, or an open filehandle to it.
"""
self.markup_url = markup_url
if hasattr(markup, 'read'):
self.doc = self._from_stream(markup)
else:
self.doc = self._from_string(markup)
self.resources = self.doc.find(wadl_xpath('resources'))
self.resource_base = self.resources.attrib.get('base')
self.representation_definitions = {}
self.resource_types = {}
for representation in self.doc.findall(wadl_xpath('representation')):
id = representation.attrib.get('id')
if id is not None:
definition = RepresentationDefinition(
self, None, representation)
self.representation_definitions[id] = definition
for resource_type in self.doc.findall(wadl_xpath('resource_type')):
id = resource_type.attrib['id']
self.resource_types[id] = ResourceType(resource_type)
def _from_stream(self, stream):
"""Turns markup into a document.
Just a wrapper around ElementTree which keeps track of namespaces.
"""
events = "start", "start-ns", "end-ns"
root = None
ns_map = []
for event, elem in ET.iterparse(stream, events):
if event == "start-ns":
ns_map.append(elem)
elif event == "end-ns":
ns_map.pop()
elif event == "start":
if root is None:
root = elem
elem.set(NS_MAP, dict(ns_map))
return ET.ElementTree(root)
def _from_string(self, markup):
"""Turns markup into a document."""
if not isinstance(markup, bytes):
markup = markup.encode("UTF-8")
return self._from_stream(io.BytesIO(markup))
def get_resource_type(self, resource_type_url):
"""Retrieve a resource type by the URL of its description."""
xml_id = self.lookup_xml_id(resource_type_url)
resource_type = self.resource_types.get(xml_id)
if resource_type is None:
raise KeyError('No such XML ID: "%s"' % resource_type_url)
return resource_type
def lookup_xml_id(self, url):
"""A helper method for locating a part of a WADL document.
:param url: The URL (with anchor) of the desired part of the
WADL document.
:return: The XML ID corresponding to the anchor.
"""
markup_uri = URI(self.markup_url).ensureNoSlash()
markup_uri.fragment = None
if url.startswith('http'):
# It's an absolute URI.
this_uri = URI(url).ensureNoSlash()
else:
# It's a relative URI.
this_uri = markup_uri.resolve(url)
possible_xml_id = this_uri.fragment
this_uri.fragment = None
if this_uri == markup_uri:
# The URL pointed elsewhere within the same WADL document.
# Return its fragment.
return possible_xml_id
# XXX leonardr 2008-05-28:
# This needs to be implemented eventually for Launchpad so
# that a script using this client can navigate from a WADL
# representation of a non-root resource to its definition at
# the server root.
raise NotImplementedError("Can't look up definition in another "
"url (%s)" % url)
def get_resource_by_path(self, path):
"""Locate one of the resources described by this document.
:param path: The path to the resource.
"""
# XXX leonardr 2008-05-27 This method only finds top-level
# resources. That's all we need for Launchpad because we don't
# define nested resources yet.
matching = [resource for resource in self.resources
if resource.attrib['path'] == path]
if len(matching) < 1:
return None
if len(matching) > 1:
raise WADLError("More than one resource defined with path %s"
% path)
return Resource(
self, merge(self.resource_base, path, True), matching[0])
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