# Copyright 2015 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.
import logging
import re
import six
import warnings
from cassandra.cqlengine import CQLEngineException, ValidationError
from cassandra.cqlengine import columns
from cassandra.cqlengine import connection
from cassandra.cqlengine import query
from cassandra.cqlengine.query import DoesNotExist as _DoesNotExist
from cassandra.cqlengine.query import MultipleObjectsReturned as _MultipleObjectsReturned
from cassandra.util import OrderedDict
log = logging.getLogger(__name__)
class ModelException(CQLEngineException):
pass
class ModelDefinitionException(ModelException):
pass
class PolymorphicModelException(ModelException):
pass
class UndefinedKeyspaceWarning(Warning):
pass
DEFAULT_KEYSPACE = None
class hybrid_classmethod(object):
"""
Allows a method to behave as both a class method and
normal instance method depending on how it's called
"""
def __init__(self, clsmethod, instmethod):
self.clsmethod = clsmethod
self.instmethod = instmethod
def __get__(self, instance, owner):
if instance is None:
return self.clsmethod.__get__(owner, owner)
else:
return self.instmethod.__get__(instance, owner)
def __call__(self, *args, **kwargs):
"""
Just a hint to IDEs that it's ok to call this
"""
raise NotImplementedError
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')
queryset = model.__queryset__(model)
# if this is a concrete polymorphic model, and the discriminator
# key is an indexed column, add a filter clause to only return
# logical rows of the proper type
if model._is_polymorphic and not model._is_polymorphic_base:
name, column = model._discriminator_column_name, model._discriminator_column
if column.partition_key or column.index:
# look for existing poly types
return queryset.filter(**{name: model.__discriminator_value__})
return queryset
def __call__(self, *args, **kwargs):
"""
Just a hint to IDEs that it's ok to call this
:rtype: ModelQuerySet
"""
raise NotImplementedError
class TransactionDescriptor(object):
"""
returns a query set descriptor
"""
def __get__(self, instance, model):
if instance:
def transaction_setter(*prepared_transaction, **unprepared_transactions):
if len(prepared_transaction) > 0:
transactions = prepared_transaction[0]
else:
transactions = instance.objects.iff(**unprepared_transactions)._transaction
instance._transaction = transactions
return instance
return transaction_setter
qs = model.__queryset__(model)
def transaction_setter(**unprepared_transactions):
transactions = model.objects.iff(**unprepared_transactions)._transaction
qs._transaction = transactions
return qs
return transaction_setter
def __call__(self, *args, **kwargs):
raise NotImplementedError
class TTLDescriptor(object):
"""
returns a query set descriptor
"""
def __get__(self, instance, model):
if instance:
# instance = copy.deepcopy(instance)
# instance method
def ttl_setter(ts):
instance._ttl = ts
return instance
return ttl_setter
qs = model.__queryset__(model)
def ttl_setter(ts):
qs._ttl = ts
return qs
return ttl_setter
def __call__(self, *args, **kwargs):
raise NotImplementedError
class TimestampDescriptor(object):
"""
returns a query set descriptor with a timestamp specified
"""
def __get__(self, instance, model):
if instance:
# instance method
def timestamp_setter(ts):
instance._timestamp = ts
return instance
return timestamp_setter
return model.objects.timestamp
def __call__(self, *args, **kwargs):
raise NotImplementedError
class IfNotExistsDescriptor(object):
"""
return a query set descriptor with a if_not_exists flag specified
"""
def __get__(self, instance, model):
if instance:
# instance method
def ifnotexists_setter(ife):
instance._if_not_exists = ife
return instance
return ifnotexists_setter
return model.objects.if_not_exists
def __call__(self, *args, **kwargs):
raise NotImplementedError
class ConsistencyDescriptor(object):
"""
returns a query set descriptor if called on Class, instance if it was an instance call
"""
def __get__(self, instance, model):
if instance:
# instance = copy.deepcopy(instance)
def consistency_setter(consistency):
instance.__consistency__ = consistency
return instance
return consistency_setter
qs = model.__queryset__(model)
def consistency_setter(consistency):
qs._consistency = consistency
return qs
return consistency_setter
def __call__(self, *args, **kwargs):
raise NotImplementedError
class ColumnQueryEvaluator(query.AbstractQueryableColumn):
"""
Wraps a column and allows it to be used in comparator
expressions, returning query operators
ie:
Model.column == 5
"""
def __init__(self, column):
self.column = column
def __unicode__(self):
return self.column.db_field_name
def _get_column(self):
""" :rtype: ColumnQueryEvaluator """
return self.column
class ColumnDescriptor(object):
"""
Handles the reading and writing of column values to and from
a model instance's value manager, as well as creating
comparator queries
"""
def __init__(self, column):
"""
:param column:
:type column: columns.Column
:return:
"""
self.column = column
self.query_evaluator = ColumnQueryEvaluator(self.column)
def __get__(self, instance, owner):
"""
Returns either the value or column, depending
on if an instance is provided or not
:param instance: the model instance
:type instance: Model
"""
try:
return instance._values[self.column.column_name].getval()
except AttributeError:
return self.query_evaluator
def __set__(self, instance, value):
"""
Sets the value on an instance, raises an exception with classes
TODO: use None instance to create update statements
"""
if instance:
return instance._values[self.column.column_name].setval(value)
else:
raise AttributeError('cannot reassign column values')
def __delete__(self, instance):
"""
Sets the column value to None, if possible
"""
if instance:
if self.column.can_delete:
instance._values[self.column.column_name].delval()
else:
raise AttributeError('cannot delete {} columns'.format(self.column.column_name))
class BaseModel(object):
"""
The base model class, don't inherit from this, inherit from Model, defined below
"""
class DoesNotExist(_DoesNotExist):
pass
class MultipleObjectsReturned(_MultipleObjectsReturned):
pass
objects = QuerySetDescriptor()
ttl = TTLDescriptor()
consistency = ConsistencyDescriptor()
iff = TransactionDescriptor()
# custom timestamps, see USING TIMESTAMP X
timestamp = TimestampDescriptor()
if_not_exists = IfNotExistsDescriptor()
# _len is lazily created by __len__
__table_name__ = None
__keyspace__ = None
__default_ttl__ = None
__polymorphic_key__ = None # DEPRECATED
__discriminator_value__ = None
# compaction options
__compaction__ = None
__compaction_tombstone_compaction_interval__ = None
__compaction_tombstone_threshold__ = None
# compaction - size tiered options
__compaction_bucket_high__ = None
__compaction_bucket_low__ = None
__compaction_max_threshold__ = None
__compaction_min_threshold__ = None
__compaction_min_sstable_size__ = None
# compaction - leveled options
__compaction_sstable_size_in_mb__ = None
# end compaction
# the queryset class used for this class
__queryset__ = query.ModelQuerySet
__dmlquery__ = query.DMLQuery
__consistency__ = None # can be set per query
# Additional table properties
__bloom_filter_fp_chance__ = None
__caching__ = None
__comment__ = None
__dclocal_read_repair_chance__ = None
__default_time_to_live__ = None
__gc_grace_seconds__ = None
__index_interval__ = None
__memtable_flush_period_in_ms__ = None
__populate_io_cache_on_flush__ = None
__read_repair_chance__ = None
__replicate_on_write__ = None
_timestamp = None # optional timestamp to include with the operation (USING TIMESTAMP)
_if_not_exists = False # optional if_not_exists flag to check existence before insertion
def __init__(self, **values):
self._values = {}
self._ttl = self.__default_ttl__
self._timestamp = None
self._transaction = None
for name, column in self._columns.items():
value = values.get(name, None)
if value is not None or isinstance(column, columns.BaseContainerColumn):
value = column.to_python(value)
value_mngr = column.value_manager(self, column, value)
if name in values:
value_mngr.explicit = True
self._values[name] = value_mngr
# a flag set by the deserializer to indicate
# that update should be used when persisting changes
self._is_persisted = False
self._batch = None
self._timeout = connection.NOT_SET
def __repr__(self):
return '{}({})'.format(self.__class__.__name__,
', '.join('{}={!r}'.format(k, getattr(self, k))
for k in self._defined_columns.keys()
if k != self._discriminator_column_name))
def __str__(self):
"""
Pretty printing of models by their primary key
"""
return '{} <{}>'.format(self.__class__.__name__,
', '.join('{}={}'.format(k, getattr(self, k)) for k in self._primary_keys.keys()))
@classmethod
def _discover_polymorphic_submodels(cls):
if not cls._is_polymorphic_base:
raise ModelException('_discover_polymorphic_submodels can only be called on polymorphic base classes')
def _discover(klass):
if not klass._is_polymorphic_base and klass.__discriminator_value__ is not None:
cls._discriminator_map[klass.__discriminator_value__] = klass
for subklass in klass.__subclasses__():
_discover(subklass)
_discover(cls)
@classmethod
def _get_model_by_discriminator_value(cls, key):
if not cls._is_polymorphic_base:
raise ModelException('_get_model_by_discriminator_value can only be called on polymorphic base classes')
return cls._discriminator_map.get(key)
@classmethod
def _construct_instance(cls, values):
"""
method used to construct instances from query results
this is where polymorphic deserialization occurs
"""
# we're going to take the values, which is from the DB as a dict
# and translate that into our local fields
# the db_map is a db_field -> model field map
items = values.items()
field_dict = dict([(cls._db_map.get(k, k), v) for k, v in items])
if cls._is_polymorphic:
disc_key = field_dict.get(cls._discriminator_column_name)
if disc_key is None:
raise PolymorphicModelException('discriminator value was not found in values')
poly_base = cls if cls._is_polymorphic_base else cls._polymorphic_base
klass = poly_base._get_model_by_discriminator_value(disc_key)
if klass is None:
poly_base._discover_polymorphic_submodels()
klass = poly_base._get_model_by_discriminator_value(disc_key)
if klass is None:
raise PolymorphicModelException(
'unrecognized discriminator column {} for class {}'.format(disc_key, poly_base.__name__)
)
if not issubclass(klass, cls):
raise PolymorphicModelException(
'{} is not a subclass of {}'.format(klass.__name__, cls.__name__)
)
field_dict = {k: v for k, v in field_dict.items() if k in klass._columns.keys()}
else:
klass = cls
instance = klass(**field_dict)
instance._is_persisted = True
return instance
def _can_update(self):
"""
Called by the save function to check if this should be
persisted with update or insert
:return:
"""
if not self._is_persisted:
return False
return all([not self._values[k].changed for k in self._primary_keys])
@classmethod
def _get_keyspace(cls):
"""
Returns the manual keyspace, if set, otherwise the default keyspace
"""
return cls.__keyspace__ or DEFAULT_KEYSPACE
@classmethod
def _get_column(cls, name):
"""
Returns the column matching the given name, raising a key error if
it doesn't exist
:param name: the name of the column to return
:rtype: Column
"""
return cls._columns[name]
def __eq__(self, other):
if self.__class__ != other.__class__:
return False
# check attribute keys
keys = set(self._columns.keys())
other_keys = set(other._columns.keys())
if keys != other_keys:
return False
# check that all of the attributes match
for key in other_keys:
if getattr(self, key, None) != getattr(other, key, None):
return False
return True
def __ne__(self, other):
return not self.__eq__(other)
@classmethod
def column_family_name(cls, include_keyspace=True):
"""
Returns the column family name if it's been defined
otherwise, it creates it from the module and class name
"""
cf_name = ''
if cls.__table_name__:
cf_name = cls.__table_name__.lower()
else:
# get polymorphic base table names if model is polymorphic
if cls._is_polymorphic and not cls._is_polymorphic_base:
return cls._polymorphic_base.column_family_name(include_keyspace=include_keyspace)
camelcase = re.compile(r'([a-z])([A-Z])')
ccase = lambda s: camelcase.sub(lambda v: '{}_{}'.format(v.group(1), v.group(2).lower()), s)
cf_name += ccase(cls.__name__)
# trim to less than 48 characters or cassandra will complain
cf_name = cf_name[-48:]
cf_name = cf_name.lower()
cf_name = re.sub(r'^_+', '', cf_name)
if not include_keyspace:
return cf_name
return '{}.{}'.format(cls._get_keyspace(), cf_name)
def validate(self):
"""
Cleans and validates the field values
"""
for name, col in self._columns.items():
v = getattr(self, name)
if v is None and not self._values[name].explicit and col.has_default:
v = col.get_default()
val = col.validate(v)
setattr(self, name, val)
# Let an instance be used like a dict of its columns keys/values
def __iter__(self):
""" Iterate over column ids. """
for column_id in self._columns.keys():
yield column_id
def __getitem__(self, key):
""" Returns column's value. """
if not isinstance(key, six.string_types):
raise TypeError
if key not in self._columns.keys():
raise KeyError
return getattr(self, key)
def __setitem__(self, key, val):
""" Sets a column's value. """
if not isinstance(key, six.string_types):
raise TypeError
if key not in self._columns.keys():
raise KeyError
return setattr(self, key, val)
def __len__(self):
"""
Returns the number of columns defined on that model.
"""
try:
return self._len
except:
self._len = len(self._columns.keys())
return self._len
def keys(self):
""" Returns a list of column IDs. """
return [k for k in self]
def values(self):
""" Returns list of column values. """
return [self[k] for k in self]
def items(self):
""" Returns a list of column ID/value tuples. """
return [(k, self[k]) for k in self]
def _as_dict(self):
""" Returns a map of column names to cleaned values """
values = self._dynamic_columns or {}
for name, col in self._columns.items():
values[name] = col.to_database(getattr(self, name, None))
return values
@classmethod
def create(cls, **kwargs):
"""
Create an instance of this model in the database.
Takes the model column values as keyword arguments.
Returns the instance.
"""
extra_columns = set(kwargs.keys()) - set(cls._columns.keys())
if extra_columns:
raise ValidationError("Incorrect columns passed: {}".format(extra_columns))
return cls.objects.create(**kwargs)
@classmethod
def all(cls):
"""
Returns a queryset representing all stored objects
This is a pass-through to the model objects().all()
"""
return cls.objects.all()
@classmethod
def filter(cls, *args, **kwargs):
"""
Returns a queryset based on filter parameters.
This is a pass-through to the model objects().:method:`~cqlengine.queries.filter`.
"""
return cls.objects.filter(*args, **kwargs)
@classmethod
def get(cls, *args, **kwargs):
"""
Returns a single object based on the passed filter constraints.
This is a pass-through to the model objects().:method:`~cqlengine.queries.get`.
"""
return cls.objects.get(*args, **kwargs)
def timeout(self, timeout):
"""
Sets a timeout for use in :meth:`~.save`, :meth:`~.update`, and :meth:`~.delete`
operations
"""
assert self._batch is None, 'Setting both timeout and batch is not supported'
self._timeout = timeout
return self
def save(self):
"""
Saves an object to the database.
.. code-block:: python
#create a person instance
person = Person(first_name='Kimberly', last_name='Eggleston')
#saves it to Cassandra
person.save()
"""
# handle polymorphic models
if self._is_polymorphic:
if self._is_polymorphic_base:
raise PolymorphicModelException('cannot save polymorphic base model')
else:
setattr(self, self._discriminator_column_name, self.__discriminator_value__)
self.validate()
self.__dmlquery__(self.__class__, self,
batch=self._batch,
ttl=self._ttl,
timestamp=self._timestamp,
consistency=self.__consistency__,
if_not_exists=self._if_not_exists,
transaction=self._transaction,
timeout=self._timeout).save()
# reset the value managers
for v in self._values.values():
v.reset_previous_value()
self._is_persisted = True
self._ttl = self.__default_ttl__
self._timestamp = None
return self
def update(self, **values):
"""
Performs an update on the model instance. You can pass in values to set on the model
for updating, or you can call without values to execute an update against any modified
fields. If no fields on the model have been modified since loading, no query will be
performed. Model validation is performed normally.
It is possible to do a blind update, that is, to update a field without having first selected the object out of the database.
See :ref:`Blind Updates <blind_updates>`
"""
for k, v in values.items():
col = self._columns.get(k)
# check for nonexistant columns
if col is None:
raise ValidationError("{}.{} has no column named: {}".format(self.__module__, self.__class__.__name__, k))
# check for primary key update attempts
if col.is_primary_key:
raise ValidationError("Cannot apply update to primary key '{}' for {}.{}".format(k, self.__module__, self.__class__.__name__))
setattr(self, k, v)
# handle polymorphic models
if self._is_polymorphic:
if self._is_polymorphic_base:
raise PolymorphicModelException('cannot update polymorphic base model')
else:
setattr(self, self._discriminator_column_name, self.__disciminator_value__)
self.validate()
self.__dmlquery__(self.__class__, self,
batch=self._batch,
ttl=self._ttl,
timestamp=self._timestamp,
consistency=self.__consistency__,
transaction=self._transaction,
timeout=self._timeout).update()
# reset the value managers
for v in self._values.values():
v.reset_previous_value()
self._is_persisted = True
self._ttl = self.__default_ttl__
self._timestamp = None
return self
def delete(self):
"""
Deletes the object from the database
"""
self.__dmlquery__(self.__class__, self,
batch=self._batch,
timestamp=self._timestamp,
consistency=self.__consistency__,
timeout=self._timeout).delete()
def get_changed_columns(self):
"""
Returns a list of the columns that have been updated since instantiation or save
"""
return [k for k, v in self._values.items() if v.changed]
@classmethod
def _class_batch(cls, batch):
return cls.objects.batch(batch)
def _inst_batch(self, batch):
assert self._timeout is connection.NOT_SET, 'Setting both timeout and batch is not supported'
self._batch = batch
return self
batch = hybrid_classmethod(_class_batch, _inst_batch)
class ModelMetaClass(type):
def __new__(cls, name, bases, attrs):
# move column definitions into columns dict
# and set default column names
column_dict = OrderedDict()
primary_keys = OrderedDict()
pk_name = None
# get inherited properties
inherited_columns = OrderedDict()
for base in bases:
for k, v in getattr(base, '_defined_columns', {}).items():
inherited_columns.setdefault(k, v)
# short circuit __abstract__ inheritance
is_abstract = attrs['__abstract__'] = attrs.get('__abstract__', False)
# short circuit __discriminator_value__ inheritance
# __polymorphic_key__ is deprecated
poly_key = attrs.get('__polymorphic_key__', None)
if poly_key:
msg = '__polymorphic_key__ is deprecated. Use __discriminator_value__ instead'
warnings.warn(msg, DeprecationWarning)
log.warning(msg)
attrs['__discriminator_value__'] = attrs.get('__discriminator_value__', poly_key)
attrs['__polymorphic_key__'] = attrs['__discriminator_value__']
def _transform_column(col_name, col_obj):
column_dict[col_name] = col_obj
if col_obj.primary_key:
primary_keys[col_name] = col_obj
col_obj.set_column_name(col_name)
# set properties
attrs[col_name] = ColumnDescriptor(col_obj)
column_definitions = [(k, v) for k, v in attrs.items() if isinstance(v, columns.Column)]
column_definitions = sorted(column_definitions, key=lambda x: x[1].position)
is_polymorphic_base = any([c[1].discriminator_column for c in column_definitions])
column_definitions = [x for x in inherited_columns.items()] + column_definitions
discriminator_columns = [c for c in column_definitions if c[1].discriminator_column]
is_polymorphic = len(discriminator_columns) > 0
if len(discriminator_columns) > 1:
raise ModelDefinitionException('only one discriminator_column (polymorphic_key (deprecated)) can be defined in a model, {} found'.format(len(discriminator_columns)))
if attrs['__discriminator_value__'] and not is_polymorphic:
raise ModelDefinitionException('__discriminator_value__ specified, but no base columns defined with discriminator_column=True')
discriminator_column_name, discriminator_column = discriminator_columns[0] if discriminator_columns else (None, None)
if isinstance(discriminator_column, (columns.BaseContainerColumn, columns.Counter)):
raise ModelDefinitionException('counter and container columns cannot be used as discriminator columns (polymorphic_key (deprecated)) ')
# find polymorphic base class
polymorphic_base = None
if is_polymorphic and not is_polymorphic_base:
def _get_polymorphic_base(bases):
for base in bases:
if getattr(base, '_is_polymorphic_base', False):
return base
klass = _get_polymorphic_base(base.__bases__)
if klass:
return klass
polymorphic_base = _get_polymorphic_base(bases)
defined_columns = OrderedDict(column_definitions)
# check for primary key
if not is_abstract and not any([v.primary_key for k, v in column_definitions]):
raise ModelDefinitionException("At least 1 primary key is required.")
counter_columns = [c for c in defined_columns.values() if isinstance(c, columns.Counter)]
data_columns = [c for c in defined_columns.values() if not c.primary_key and not isinstance(c, columns.Counter)]
if counter_columns and data_columns:
raise ModelDefinitionException('counter models may not have data columns')
has_partition_keys = any(v.partition_key for (k, v) in column_definitions)
# transform column definitions
for k, v in column_definitions:
# don't allow a column with the same name as a built-in attribute or method
if k in BaseModel.__dict__:
raise ModelDefinitionException("column '{}' conflicts with built-in attribute/method".format(k))
# counter column primary keys are not allowed
if (v.primary_key or v.partition_key) and isinstance(v, (columns.Counter, columns.BaseContainerColumn)):
raise ModelDefinitionException('counter columns and container columns cannot be used as primary keys')
# this will mark the first primary key column as a partition
# key, if one hasn't been set already
if not has_partition_keys and v.primary_key:
v.partition_key = True
has_partition_keys = True
_transform_column(k, v)
partition_keys = OrderedDict(k for k in primary_keys.items() if k[1].partition_key)
clustering_keys = OrderedDict(k for k in primary_keys.items() if not k[1].partition_key)
# setup partition key shortcut
if len(partition_keys) == 0:
if not is_abstract:
raise ModelException("at least one partition key must be defined")
if len(partition_keys) == 1:
pk_name = [x for x in partition_keys.keys()][0]
attrs['pk'] = attrs[pk_name]
else:
# composite partition key case, get/set a tuple of values
_get = lambda self: tuple(self._values[c].getval() for c in partition_keys.keys())
_set = lambda self, val: tuple(self._values[c].setval(v) for (c, v) in zip(partition_keys.keys(), val))
attrs['pk'] = property(_get, _set)
# some validation
col_names = set()
for v in column_dict.values():
# check for duplicate column names
if v.db_field_name in col_names:
raise ModelException("{} defines the column {} more than once".format(name, v.db_field_name))
if v.clustering_order and not (v.primary_key and not v.partition_key):
raise ModelException("clustering_order may be specified only for clustering primary keys")
if v.clustering_order and v.clustering_order.lower() not in ('asc', 'desc'):
raise ModelException("invalid clustering order {} for column {}".format(repr(v.clustering_order), v.db_field_name))
col_names.add(v.db_field_name)
# create db_name -> model name map for loading
db_map = {}
for field_name, col in column_dict.items():
db_map[col.db_field_name] = field_name
# add management members to the class
attrs['_columns'] = column_dict
attrs['_primary_keys'] = primary_keys
attrs['_defined_columns'] = defined_columns
# maps the database field to the models key
attrs['_db_map'] = db_map
attrs['_pk_name'] = pk_name
attrs['_dynamic_columns'] = {}
attrs['_partition_keys'] = partition_keys
attrs['_clustering_keys'] = clustering_keys
attrs['_has_counter'] = len(counter_columns) > 0
# add polymorphic management attributes
attrs['_is_polymorphic_base'] = is_polymorphic_base
attrs['_is_polymorphic'] = is_polymorphic
attrs['_polymorphic_base'] = polymorphic_base
attrs['_discriminator_column'] = discriminator_column
attrs['_discriminator_column_name'] = discriminator_column_name
attrs['_discriminator_map'] = {} if is_polymorphic_base else None
# setup class exceptions
DoesNotExistBase = None
for base in bases:
DoesNotExistBase = getattr(base, 'DoesNotExist', None)
if DoesNotExistBase is not None:
break
DoesNotExistBase = DoesNotExistBase or attrs.pop('DoesNotExist', BaseModel.DoesNotExist)
attrs['DoesNotExist'] = type('DoesNotExist', (DoesNotExistBase,), {})
MultipleObjectsReturnedBase = None
for base in bases:
MultipleObjectsReturnedBase = getattr(base, 'MultipleObjectsReturned', None)
if MultipleObjectsReturnedBase is not None:
break
MultipleObjectsReturnedBase = DoesNotExistBase or attrs.pop('MultipleObjectsReturned', BaseModel.MultipleObjectsReturned)
attrs['MultipleObjectsReturned'] = type('MultipleObjectsReturned', (MultipleObjectsReturnedBase,), {})
# create the class and add a QuerySet to it
klass = super(ModelMetaClass, cls).__new__(cls, name, bases, attrs)
udts = []
for col in column_dict.values():
columns.resolve_udts(col, udts)
for user_type in set(udts):
user_type.register_for_keyspace(klass._get_keyspace())
return klass
@six.add_metaclass(ModelMetaClass)
[docs]class Model(BaseModel):
__abstract__ = True
"""
*Optional.* Indicates that this model is only intended to be used as a base class for other models.
You can't create tables for abstract models, but checks around schema validity are skipped during class construction.
"""
__table_name__ = None
"""
*Optional.* Sets the name of the CQL table for this model. If left blank, the table name will be the name of the model, with it's module name as it's prefix. Manually defined table names are not inherited.
"""
__keyspace__ = None
"""
Sets the name of the keyspace used by this model.
"""
__default_ttl__ = None
"""
*Optional* The default ttl used by this model.
This can be overridden by using the :meth:`~.ttl` method.
"""
__polymorphic_key__ = None
"""
*Deprecated.*
see :attr:`~.__discriminator_value__`
"""
__discriminator_value__ = None
"""
*Optional* Specifies a value for the discriminator column when using model inheritance.
"""