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named.py
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# Copyright 2013-2017 DataStax, Inc.
#
# 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.
from cassandra.util import OrderedDict
from cassandra.cqlengine import CQLEngineException
from cassandra.cqlengine.columns import Column
from cassandra.cqlengine.connection import get_cluster
from cassandra.cqlengine.models import UsingDescriptor, BaseModel
from cassandra.cqlengine.query import AbstractQueryableColumn, SimpleQuerySet
from cassandra.cqlengine.query import DoesNotExist as _DoesNotExist
from cassandra.cqlengine.query import MultipleObjectsReturned as _MultipleObjectsReturned
class QuerySetDescriptor(object):
"""
returns a fresh queryset for the given model
it's declared on everytime it's accessed
"""
def __get__(self, obj, model):
""" :rtype: ModelQuerySet """
if model.__abstract__:
raise CQLEngineException('cannot execute queries against abstract models')
return SimpleQuerySet(obj)
def __call__(self, *args, **kwargs):
"""
Just a hint to IDEs that it's ok to call this
:rtype: ModelQuerySet
"""
raise NotImplementedError
class NamedColumn(AbstractQueryableColumn):
"""
A column that is not coupled to a model class, or type
"""
def __init__(self, name):
self.name = name
def __unicode__(self):
return self.name
def _get_column(self):
""" :rtype: NamedColumn """
return self
@property
def db_field_name(self):
return self.name
@property
def cql(self):
return self.get_cql()
def get_cql(self):
return '"{0}"'.format(self.name)
def to_database(self, val):
return val
class NamedTable(object):
"""
A Table that is not coupled to a model class
"""
__abstract__ = False
objects = QuerySetDescriptor()
__partition_keys = None
_partition_key_index = None
__connection__ = None
_connection = None
using = UsingDescriptor()
_get_connection = BaseModel._get_connection
class DoesNotExist(_DoesNotExist):
pass
class MultipleObjectsReturned(_MultipleObjectsReturned):
pass
def __init__(self, keyspace, name):
self.keyspace = keyspace
self.name = name
self._connection = None
@property
def _partition_keys(self):
if not self.__partition_keys:
self._get_partition_keys()
return self.__partition_keys
def _get_partition_keys(self):
try:
table_meta = get_cluster(self._get_connection()).metadata.keyspaces[self.keyspace].tables[self.name]
self.__partition_keys = OrderedDict((pk.name, Column(primary_key=True, partition_key=True, db_field=pk.name)) for pk in table_meta.partition_key)
except Exception as e:
raise CQLEngineException("Failed inspecting partition keys for {0}."
"Ensure cqlengine is connected before attempting this with NamedTable.".format(self.column_family_name()))
def column(self, name):
return NamedColumn(name)
def column_family_name(self, include_keyspace=True):
"""
Returns the column family name if it's been defined
otherwise, it creates it from the module and class name
"""
if include_keyspace:
return '{0}.{1}'.format(self.keyspace, self.name)
else:
return self.name
def _get_column(self, name):
"""
Returns the column matching the given name
:rtype: Column
"""
return self.column(name)
# def create(self, **kwargs):
# return self.objects.create(**kwargs)
def all(self):
return self.objects.all()
def filter(self, *args, **kwargs):
return self.objects.filter(*args, **kwargs)
def get(self, *args, **kwargs):
return self.objects.get(*args, **kwargs)
class NamedKeyspace(object):
"""
A keyspace
"""
def __init__(self, name):
self.name = name
def table(self, name):
"""
returns a table descriptor with the given
name that belongs to this keyspace
"""
return NamedTable(self.name, name)