# Copyright 2014 Google Inc. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Create / interact with gcloud datastore keys."""
import copy
import six
from gcloud.datastore._generated import entity_pb2 as _entity_pb2
class Key(object):
"""An immutable representation of a datastore Key.
To create a basic key:
>>> Key('EntityKind', 1234)
<Key[{'kind': 'EntityKind', 'id': 1234}]>
>>> Key('EntityKind', 'foo')
<Key[{'kind': 'EntityKind', 'name': 'foo'}]>
To create a key with a parent:
>>> Key('Parent', 'foo', 'Child', 1234)
<Key[{'kind': 'Parent', 'name': 'foo'}, {'kind': 'Child', 'id': 1234}]>
>>> Key('Child', 1234, parent=parent_key)
<Key[{'kind': 'Parent', 'name': 'foo'}, {'kind': 'Child', 'id': 1234}]>
To create a partial key:
>>> Key('Parent', 'foo', 'Child')
<Key[{'kind': 'Parent', 'name': 'foo'}, {'kind': 'Child'}]>
:type path_args: tuple of string and integer
:param path_args: May represent a partial (odd length) or full (even
length) key path.
:type kwargs: dict
:param kwargs: Keyword arguments to be passed in.
Accepted keyword arguments are
* namespace (string): A namespace identifier for the key.
* project (string): The project associated with the key.
* parent (:class:`gcloud.datastore.key.Key`): The parent of the key.
The project argument is required unless it has been set implicitly.
"""
def __init__(self, *path_args, **kwargs):
self._flat_path = path_args
parent = self._parent = kwargs.get('parent')
self._namespace = kwargs.get('namespace')
project = kwargs.get('project')
self._project = _validate_project(project, parent)
# _flat_path, _parent, _namespace and _project must be set before
# _combine_args() is called.
self._path = self._combine_args()
def __eq__(self, other):
"""Compare two keys for equality.
Incomplete keys never compare equal to any other key.
Completed keys compare equal if they have the same path, project,
and namespace.
:rtype: bool
:returns: True if the keys compare equal, else False.
"""
if not isinstance(other, Key):
return False
if self.is_partial or other.is_partial:
return False
return (self.flat_path == other.flat_path and
self.project == other.project and
self.namespace == other.namespace)
def __ne__(self, other):
"""Compare two keys for inequality.
Incomplete keys never compare equal to any other key.
Completed keys compare equal if they have the same path, project,
and namespace.
:rtype: bool
:returns: False if the keys compare equal, else True.
"""
return not self.__eq__(other)
def __hash__(self):
"""Hash a keys for use in a dictionary lookp.
:rtype: integer
:returns: a hash of the key's state.
"""
return (hash(self.flat_path) +
hash(self.project) +
hash(self.namespace))
@staticmethod
def _parse_path(path_args):
"""Parses positional arguments into key path with kinds and IDs.
:type path_args: tuple
:param path_args: A tuple from positional arguments. Should be
alternating list of kinds (string) and ID/name
parts (int or string).
:rtype: :class:`list` of :class:`dict`
:returns: A list of key parts with kind and ID or name set.
:raises: :class:`ValueError` if there are no ``path_args``, if one of
the kinds is not a string or if one of the IDs/names is not
a string or an integer.
"""
if len(path_args) == 0:
raise ValueError('Key path must not be empty.')
kind_list = path_args[::2]
id_or_name_list = path_args[1::2]
# Dummy sentinel value to pad incomplete key to even length path.
partial_ending = object()
if len(path_args) % 2 == 1:
id_or_name_list += (partial_ending,)
result = []
for kind, id_or_name in zip(kind_list, id_or_name_list):
curr_key_part = {}
if isinstance(kind, six.string_types):
curr_key_part['kind'] = kind
else:
raise ValueError(kind, 'Kind was not a string.')
if isinstance(id_or_name, six.string_types):
curr_key_part['name'] = id_or_name
elif isinstance(id_or_name, six.integer_types):
curr_key_part['id'] = id_or_name
elif id_or_name is not partial_ending:
raise ValueError(id_or_name,
'ID/name was not a string or integer.')
result.append(curr_key_part)
return result
def _combine_args(self):
"""Sets protected data by combining raw data set from the constructor.
If a ``_parent`` is set, updates the ``_flat_path`` and sets the
``_namespace`` and ``_project`` if not already set.
:rtype: :class:`list` of :class:`dict`
:returns: A list of key parts with kind and ID or name set.
:raises: :class:`ValueError` if the parent key is not complete.
"""
child_path = self._parse_path(self._flat_path)
if self._parent is not None:
if self._parent.is_partial:
raise ValueError('Parent key must be complete.')
# We know that _parent.path() will return a copy.
child_path = self._parent.path + child_path
self._flat_path = self._parent.flat_path + self._flat_path
if (self._namespace is not None and
self._namespace != self._parent.namespace):
raise ValueError('Child namespace must agree with parent\'s.')
self._namespace = self._parent.namespace
if (self._project is not None and
self._project != self._parent.project):
raise ValueError('Child project must agree with parent\'s.')
self._project = self._parent.project
return child_path
def _clone(self):
"""Duplicates the Key.
Most attributes are simple types, so don't require copying. Other
attributes like ``parent`` are long-lived and so we re-use them.
:rtype: :class:`gcloud.datastore.key.Key`
:returns: A new ``Key`` instance with the same data as the current one.
"""
cloned_self = self.__class__(*self.flat_path,
project=self.project,
namespace=self.namespace)
# If the current parent has already been set, we re-use
# the same instance
cloned_self._parent = self._parent
return cloned_self
def completed_key(self, id_or_name):
"""Creates new key from existing partial key by adding final ID/name.
:type id_or_name: string or integer
:param id_or_name: ID or name to be added to the key.
:rtype: :class:`gcloud.datastore.key.Key`
:returns: A new ``Key`` instance with the same data as the current one
and an extra ID or name added.
:raises: :class:`ValueError` if the current key is not partial or if
``id_or_name`` is not a string or integer.
"""
if not self.is_partial:
raise ValueError('Only a partial key can be completed.')
id_or_name_key = None
if isinstance(id_or_name, six.string_types):
id_or_name_key = 'name'
elif isinstance(id_or_name, six.integer_types):
id_or_name_key = 'id'
else:
raise ValueError(id_or_name,
'ID/name was not a string or integer.')
new_key = self._clone()
new_key._path[-1][id_or_name_key] = id_or_name
new_key._flat_path += (id_or_name,)
return new_key
def to_protobuf(self):
"""Return a protobuf corresponding to the key.
:rtype: :class:`gcloud.datastore._generated.entity_pb2.Key`
:returns: The protobuf representing the key.
"""
key = _entity_pb2.Key()
key.partition_id.project_id = self.project
if self.namespace:
key.partition_id.namespace_id = self.namespace
for item in self.path:
element = key.path.add()
if 'kind' in item:
element.kind = item['kind']
if 'id' in item:
element.id = item['id']
if 'name' in item:
element.name = item['name']
return key
@property
def is_partial(self):
"""Boolean indicating if the key has an ID (or name).
:rtype: bool
:returns: ``True`` if the last element of the key's path does not have
an ``id`` or a ``name``.
"""
return self.id_or_name is None
@property
def namespace(self):
"""Namespace getter.
:rtype: string
:returns: The namespace of the current key.
"""
return self._namespace
@property
def path(self):
"""Path getter.
Returns a copy so that the key remains immutable.
:rtype: :class:`list` of :class:`dict`
:returns: The (key) path of the current key.
"""
return copy.deepcopy(self._path)
@property
def flat_path(self):
"""Getter for the key path as a tuple.
:rtype: tuple of string and integer
:returns: The tuple of elements in the path.
"""
return self._flat_path
@property
def kind(self):
"""Kind getter. Based on the last element of path.
:rtype: string
:returns: The kind of the current key.
"""
return self.path[-1]['kind']
@property
def id(self):
"""ID getter. Based on the last element of path.
:rtype: integer
:returns: The (integer) ID of the key.
"""
return self.path[-1].get('id')
@property
def name(self):
"""Name getter. Based on the last element of path.
:rtype: string
:returns: The (string) name of the key.
"""
return self.path[-1].get('name')
@property
def id_or_name(self):
"""Getter. Based on the last element of path.
:rtype: integer (if ``id``) or string (if ``name``)
:returns: The last element of the key's path if it is either an ``id``
or a ``name``.
"""
return self.id or self.name
@property
def project(self):
"""Project getter.
:rtype: string
:returns: The key's project.
"""
return self._project
def _make_parent(self):
"""Creates a parent key for the current path.
Extracts all but the last element in the key path and creates a new
key, while still matching the namespace and the project.
:rtype: :class:`gcloud.datastore.key.Key` or :class:`NoneType`
:returns: A new ``Key`` instance, whose path consists of all but the
last element of current path. If the current key has only
one path element, returns ``None``.
"""
if self.is_partial:
parent_args = self.flat_path[:-1]
else:
parent_args = self.flat_path[:-2]
if parent_args:
return self.__class__(*parent_args, project=self.project,
namespace=self.namespace)
@property
def parent(self):
"""The parent of the current key.
:rtype: :class:`gcloud.datastore.key.Key` or :class:`NoneType`
:returns: A new ``Key`` instance, whose path consists of all but the
last element of current path. If the current key has only
one path element, returns ``None``.
"""
if self._parent is None:
self._parent = self._make_parent()
return self._parent
def __repr__(self):
return '<Key%s, project=%s>' % (self.path, self.project)
def _validate_project(project, parent):
"""Ensure the project is set appropriately.
If ``parent`` is passed, skip the test (it will be checked / fixed up
later).
If ``project`` is unset, attempt to infer the project from the environment.
:type project: string
:param project: A project.
:type parent: :class:`gcloud.datastore.key.Key` or ``NoneType``
:param parent: The parent of the key or ``None``.
:rtype: string
:returns: The ``project`` passed in, or implied from the environment.
:raises: :class:`ValueError` if ``project`` is ``None`` and no project
can be inferred from the parent.
"""
if parent is None:
if project is None:
raise ValueError("A Key must have a project set.")
return project