377 lines
10 KiB
Python
377 lines
10 KiB
Python
# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import abc
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import collections
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import six
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from six.moves.urllib import parse as url_parse
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from openstack import exceptions
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from openstack import utils
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class prop(object):
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"""A helper for defining properties on a Resource.
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A Resource.prop defines some known attributes within a resource's values.
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For example we know a User resource will have a name:
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>>> class User(Resource):
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... name = prop('name')
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...
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>>> u = User()
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>>> u.name = 'John Doe'
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>>> print u['name']
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John Doe
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User objects can now be accessed via the User().name attribute. The 'name'
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value we pass as an attribute is the name of the attribute in the message.
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This means that you don't need to use the same name for your attribute as
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will be set within the object. For example:
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>>> class User(Resource):
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... name = prop('userName')
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...
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>>> u = User()
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>>> u.name = 'John Doe'
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>>> print u['userName']
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John Doe
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There is limited validation ability in props.
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You can validate the type of values that are set:
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>>> class User(Resource):
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... name = prop('userName')
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... age = prop('age', type=int)
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...
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>>> u = User()
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>>> u.age = 'thirty'
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TypeError: Invalid type for attr age
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"""
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def __init__(self, name, type=None):
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self.name = name
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self.type = type
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def __get__(self, instance, owner):
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try:
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return instance._attrs[self.name]
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except KeyError:
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raise AttributeError('Unset property: %s', self.name)
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def __set__(self, instance, value):
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if self.type and not isinstance(value, self.type):
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raise TypeError('Invalid type for attr %s' % self.name)
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instance._attrs[self.name] = value
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def __delete__(self, instance):
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try:
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del instance._attrs[self.name]
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except KeyError:
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raise AttributeError('Unset property: %s', self.name)
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@six.add_metaclass(abc.ABCMeta)
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class Resource(collections.MutableMapping):
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"""A base class that represents a remote resource.
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Attributes of the resource are defined by the responses from the server
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rather than in code so that we don't have to try and keep up with all
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possible attributes and extensions. This may be changed in the future.
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For update management we maintain a dirty list so when updating an object
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only the attributes that have actually been changed are sent to the server.
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There is some support here for lazy loading that needs improvement.
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"""
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# the singular and plural forms of the key element
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resource_key = None
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resources_key = None
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# The attribute associated with the name
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name_attribute = 'name'
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# the base part of the url for this resource
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base_path = ''
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# The service this belongs to. e.g. 'identity'
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# (unused, is a session/auth_plugin attribute for determining URL)
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service = None
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# limit the abilities of a subclass. You should set these to true if your
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# resource supports that function.
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allow_create = False
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allow_retrieve = False
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allow_update = False
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allow_delete = False
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allow_list = False
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def __init__(self, attrs=None, loaded=False):
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if attrs is None:
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attrs = {}
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self._id = attrs.pop('id', None)
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self._attrs = attrs
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self._dirty = set() if loaded else set(attrs.keys())
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self._loaded = loaded
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def __repr__(self):
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if self._id is not None:
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d = {'id': self._id}
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d.update(self._attrs)
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else:
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d = self._attrs
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return "%s: %s" % (self.resource_key, d)
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##
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# CONSTRUCTORS
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##
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@classmethod
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def new(cls, **kwargs):
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"""Create a new instance of this resource.
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Internally set flags such that it is marked as not present on the
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server.
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"""
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return cls(kwargs, loaded=False)
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@classmethod
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def existing(cls, **kwargs):
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"""Create a new object representation of an existing resource.
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It is marked as an exact replication of a resource present on a server.
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"""
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return cls(kwargs, loaded=True)
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##
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# MUTABLE MAPPING IMPLEMENTATION
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##
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def __getitem__(self, name):
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return self._attrs[name]
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def __setitem__(self, name, value):
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try:
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orig = self._attrs[name]
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except KeyError:
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changed = True
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else:
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changed = orig != value
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if changed:
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self._attrs[name] = value
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self._dirty.add(name)
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def __delitem__(self, name):
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del self._attrs[name]
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self._dirty.add(name)
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def __len__(self):
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return len(self._attrs)
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def __iter__(self):
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return iter(self._attrs)
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##
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# BASE PROPERTIES/OPERATIONS
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##
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@property
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def id(self):
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# id is read only
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return self._id
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@id.deleter
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def id_del(self):
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self._id = None
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@property
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def is_dirty(self):
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return len(self._dirty) > 0
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def _reset_dirty(self):
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self._dirty = set()
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##
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# CRUD OPERATIONS
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##
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@classmethod
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def create_by_id(cls, session, attrs, r_id=None):
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if not cls.allow_create:
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raise exceptions.MethodNotSupported('create')
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if cls.resource_key:
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body = {cls.resource_key: attrs}
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else:
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body = attrs
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if r_id:
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url = utils.urljoin(cls.base_path, r_id)
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resp = session.put(url, service=cls.service, json=body).body
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else:
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resp = session.post(cls.base_path, service=cls.service,
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json=body).body
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if cls.resource_key:
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resp = resp[cls.resource_key]
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return resp
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def create(self, session):
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resp = self.create_by_id(session, self._attrs, self.id)
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self._id = resp.pop('id')
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self._reset_dirty()
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@classmethod
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def get_data_by_id(cls, session, r_id):
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if not cls.allow_retrieve:
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raise exceptions.MethodNotSupported('retrieve')
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url = utils.urljoin(cls.base_path, r_id)
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body = session.get(url, service=cls.service).body
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if cls.resource_key:
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body = body[cls.resource_key]
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return body
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@classmethod
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def get_by_id(cls, session, r_id):
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body = cls.get_data_by_id(session, r_id)
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return cls.existing(**body)
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def get(self, session):
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body = self.get_data_by_id(session, self.id)
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self._attrs.update(body)
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self._loaded = True
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@classmethod
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def head_data_by_id(cls, session, r_id):
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if not cls.allow_retrieve:
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raise exceptions.MethodNotSupported('retrieve')
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url = utils.urljoin(cls.base_path, r_id)
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data = session.head(url, service=cls.service, accept=None).headers
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resp_id = data.pop("X-Trans-Id", None)
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if resp_id:
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data["id"] = resp_id
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return data
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@classmethod
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def head_by_id(cls, session, r_id):
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data = cls.head_data_by_id(session, r_id)
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return cls.existing(**data)
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def head(self, session):
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data = self.head_data_by_id(session, self.id)
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self._attrs.update(data)
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self._loaded = True
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@classmethod
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def update_by_id(cls, session, r_id, attrs):
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if not cls.allow_update:
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raise exceptions.MethodNotSupported('update')
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if cls.resource_key:
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body = {cls.resource_key: attrs}
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else:
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body = attrs
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url = utils.urljoin(cls.base_path, r_id)
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resp = session.patch(url, service=cls.service, json=body).body
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if cls.resource_key:
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resp = resp[cls.resource_key]
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return resp
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def update(self, session):
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if not self.is_dirty:
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return
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dirty_attrs = dict((k, self._attrs[k]) for k in self._dirty)
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resp = self.update_by_id(session, self.id, dirty_attrs)
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try:
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resp_id = resp.pop('id')
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except KeyError:
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pass
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else:
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assert resp_id == self.id
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self._reset_dirty()
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@classmethod
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def delete_by_id(cls, session, r_id):
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if not cls.allow_delete:
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raise exceptions.MethodNotSupported('delete')
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url = utils.urljoin(cls.base_path, r_id)
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session.delete(url, service=cls.service, accept=None)
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def delete(self, session):
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self.delete_by_id(session, self.id)
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@classmethod
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def list(cls, session, limit=None, marker=None, **params):
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# NOTE(jamielennox): Is it possible we can return a generator from here
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# and allow us to keep paging rather than limit and marker?
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if not cls.allow_list:
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raise exceptions.MethodNotSupported('retrieve')
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filters = {}
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if limit:
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filters['limit'] = limit
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if marker:
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filters['marker'] = marker
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url = cls.base_path
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if filters:
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url = '%s?%s' % (url, url_parse.urlencode(filters))
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resp = session.get(url, service=cls.service, params=params).body
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if cls.resources_key:
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resp = resp[cls.resources_key]
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return [cls.existing(**data) for data in resp]
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@classmethod
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def find(cls, session, name_or_id):
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try:
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info = cls.list(session, id=name_or_id, fields='id')
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if len(info) == 1:
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return info[0]
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except exceptions.HttpException:
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pass
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if cls.name_attribute:
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params = {cls.name_attribute: name_or_id, 'fields': 'id'}
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info = cls.list(session, **params)
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if len(info) == 1:
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return info[0]
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if len(info) > 1:
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msg = "More than one %s exists with the name '%s'."
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msg = (msg % (cls.resource_key, name_or_id))
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raise exceptions.DuplicateResource(msg)
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msg = ("No %s with a name or ID of '%s' exists." %
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(cls.resource_key, name_or_id))
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raise exceptions.ResourceNotFound(msg)
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