704 lines
24 KiB
Python
704 lines
24 KiB
Python
from collections import OrderedDict
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import re
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from cqlengine import columns
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from cqlengine.exceptions import ModelException, CQLEngineException, ValidationError
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from cqlengine.query import ModelQuerySet, DMLQuery, AbstractQueryableColumn
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from cqlengine.query import DoesNotExist as _DoesNotExist
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from cqlengine.query import MultipleObjectsReturned as _MultipleObjectsReturned
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class ModelDefinitionException(ModelException): pass
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class PolyMorphicModelException(ModelException): pass
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DEFAULT_KEYSPACE = 'cqlengine'
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class hybrid_classmethod(object):
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"""
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Allows a method to behave as both a class method and
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normal instance method depending on how it's called
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"""
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def __init__(self, clsmethod, instmethod):
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self.clsmethod = clsmethod
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self.instmethod = instmethod
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def __get__(self, instance, owner):
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if instance is None:
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return self.clsmethod.__get__(owner, owner)
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else:
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return self.instmethod.__get__(instance, owner)
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def __call__(self, *args, **kwargs):
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"""
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Just a hint to IDEs that it's ok to call this
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"""
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raise NotImplementedError
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class QuerySetDescriptor(object):
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"""
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returns a fresh queryset for the given model
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it's declared on everytime it's accessed
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"""
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def __get__(self, obj, model):
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""" :rtype: ModelQuerySet """
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if model.__abstract__:
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raise CQLEngineException('cannot execute queries against abstract models')
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queryset = model.__queryset__(model)
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# if this is a concrete polymorphic model, and the polymorphic
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# key is an indexed column, add a filter clause to only return
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# logical rows of the proper type
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if model._is_polymorphic and not model._is_polymorphic_base:
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name, column = model._polymorphic_column_name, model._polymorphic_column
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if column.partition_key or column.index:
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# look for existing poly types
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return queryset.filter(**{name: model.__polymorphic_key__})
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return queryset
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def __call__(self, *args, **kwargs):
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"""
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Just a hint to IDEs that it's ok to call this
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:rtype: ModelQuerySet
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"""
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raise NotImplementedError
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class TTLDescriptor(object):
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"""
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returns a query set descriptor
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"""
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def __get__(self, instance, model):
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if instance:
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#instance = copy.deepcopy(instance)
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# instance method
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def ttl_setter(ts):
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instance._ttl = ts
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return instance
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return ttl_setter
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qs = model.__queryset__(model)
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def ttl_setter(ts):
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qs._ttl = ts
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return qs
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return ttl_setter
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def __call__(self, *args, **kwargs):
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raise NotImplementedError
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class TimestampDescriptor(object):
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"""
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returns a query set descriptor with a timestamp specified
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"""
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def __get__(self, instance, model):
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if instance:
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# instance method
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def timestamp_setter(ts):
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instance._timestamp = ts
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return instance
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return timestamp_setter
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return model.objects.timestamp
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def __call__(self, *args, **kwargs):
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raise NotImplementedError
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class ConsistencyDescriptor(object):
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"""
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returns a query set descriptor if called on Class, instance if it was an instance call
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"""
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def __get__(self, instance, model):
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if instance:
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#instance = copy.deepcopy(instance)
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def consistency_setter(consistency):
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instance.__consistency__ = consistency
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return instance
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return consistency_setter
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qs = model.__queryset__(model)
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def consistency_setter(consistency):
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qs._consistency = consistency
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return qs
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return consistency_setter
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def __call__(self, *args, **kwargs):
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raise NotImplementedError
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class ColumnQueryEvaluator(AbstractQueryableColumn):
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"""
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Wraps a column and allows it to be used in comparator
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expressions, returning query operators
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ie:
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Model.column == 5
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"""
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def __init__(self, column):
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self.column = column
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def __unicode__(self):
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return self.column.db_field_name
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def _get_column(self):
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""" :rtype: ColumnQueryEvaluator """
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return self.column
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class ColumnDescriptor(object):
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"""
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Handles the reading and writing of column values to and from
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a model instance's value manager, as well as creating
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comparator queries
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"""
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def __init__(self, column):
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"""
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:param column:
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:type column: columns.Column
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:return:
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"""
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self.column = column
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self.query_evaluator = ColumnQueryEvaluator(self.column)
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def __get__(self, instance, owner):
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"""
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Returns either the value or column, depending
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on if an instance is provided or not
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:param instance: the model instance
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:type instance: Model
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"""
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if instance:
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return instance._values[self.column.column_name].getval()
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else:
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return self.query_evaluator
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def __set__(self, instance, value):
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"""
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Sets the value on an instance, raises an exception with classes
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TODO: use None instance to create update statements
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"""
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if instance:
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return instance._values[self.column.column_name].setval(value)
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else:
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raise AttributeError('cannot reassign column values')
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def __delete__(self, instance):
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"""
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Sets the column value to None, if possible
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"""
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if instance:
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if self.column.can_delete:
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instance._values[self.column.column_name].delval()
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else:
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raise AttributeError('cannot delete {} columns'.format(self.column.column_name))
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class BaseModel(object):
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"""
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The base model class, don't inherit from this, inherit from Model, defined below
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"""
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class DoesNotExist(_DoesNotExist): pass
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class MultipleObjectsReturned(_MultipleObjectsReturned): pass
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objects = QuerySetDescriptor()
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ttl = TTLDescriptor()
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consistency = ConsistencyDescriptor()
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# custom timestamps, see USING TIMESTAMP X
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timestamp = TimestampDescriptor()
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# table names will be generated automatically from it's model
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# however, you can also define them manually here
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__table_name__ = None
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# the keyspace for this model
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__keyspace__ = None
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# polymorphism options
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__polymorphic_key__ = None
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# compaction options
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__compaction__ = None
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__compaction_tombstone_compaction_interval__ = None
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__compaction_tombstone_threshold__ = None
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# compaction - size tiered options
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__compaction_bucket_high__ = None
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__compaction_bucket_low__ = None
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__compaction_max_threshold__ = None
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__compaction_min_threshold__ = None
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__compaction_min_sstable_size__ = None
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# compaction - leveled options
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__compaction_sstable_size_in_mb__ = None
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# end compaction
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# the queryset class used for this class
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__queryset__ = ModelQuerySet
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__dmlquery__ = DMLQuery
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#__ttl__ = None # this doesn't seem to be used
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__consistency__ = None # can be set per query
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__read_repair_chance__ = 0.1
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_timestamp = None # optional timestamp to include with the operation (USING TIMESTAMP)
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def __init__(self, **values):
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self._values = {}
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self._ttl = None
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self._timestamp = None
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for name, column in self._columns.items():
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value = values.get(name, None)
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if value is not None or isinstance(column, columns.BaseContainerColumn):
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value = column.to_python(value)
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value_mngr = column.value_manager(self, column, value)
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self._values[name] = value_mngr
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# a flag set by the deserializer to indicate
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# that update should be used when persisting changes
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self._is_persisted = False
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self._batch = None
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def __repr__(self):
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"""
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Pretty printing of models by their primary key
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"""
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return '{} <{}>'.format(self.__class__.__name__,
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', '.join(('{}={}'.format(k, getattr(self, k)) for k,v in self._primary_keys.iteritems()))
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)
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@classmethod
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def _discover_polymorphic_submodels(cls):
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if not cls._is_polymorphic_base:
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raise ModelException('_discover_polymorphic_submodels can only be called on polymorphic base classes')
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def _discover(klass):
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if not klass._is_polymorphic_base and klass.__polymorphic_key__ is not None:
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cls._polymorphic_map[klass.__polymorphic_key__] = klass
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for subklass in klass.__subclasses__():
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_discover(subklass)
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_discover(cls)
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@classmethod
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def _get_model_by_polymorphic_key(cls, key):
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if not cls._is_polymorphic_base:
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raise ModelException('_get_model_by_polymorphic_key can only be called on polymorphic base classes')
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return cls._polymorphic_map.get(key)
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@classmethod
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def _construct_instance(cls, names, values):
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"""
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method used to construct instances from query results
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this is where polymorphic deserialization occurs
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"""
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field_dict = dict((cls._db_map.get(k, k), v) for k, v in zip(names, values))
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if cls._is_polymorphic:
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poly_key = field_dict.get(cls._polymorphic_column_name)
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if poly_key is None:
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raise PolyMorphicModelException('polymorphic key was not found in values')
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poly_base = cls if cls._is_polymorphic_base else cls._polymorphic_base
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klass = poly_base._get_model_by_polymorphic_key(poly_key)
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if klass is None:
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poly_base._discover_polymorphic_submodels()
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klass = poly_base._get_model_by_polymorphic_key(poly_key)
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if klass is None:
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raise PolyMorphicModelException(
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'unrecognized polymorphic key {} for class {}'.format(poly_key, poly_base.__name__)
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)
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if not issubclass(klass, cls):
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raise PolyMorphicModelException(
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'{} is not a subclass of {}'.format(klass.__name__, cls.__name__)
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)
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field_dict = {k: v for k, v in field_dict.items() if k in klass._columns.keys()}
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else:
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klass = cls
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instance = klass(**field_dict)
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instance._is_persisted = True
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return instance
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def _can_update(self):
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"""
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Called by the save function to check if this should be
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persisted with update or insert
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:return:
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"""
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if not self._is_persisted: return False
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pks = self._primary_keys.keys()
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return all([not self._values[k].changed for k in self._primary_keys])
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@classmethod
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def _get_keyspace(cls):
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""" Returns the manual keyspace, if set, otherwise the default keyspace """
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return cls.__keyspace__ or DEFAULT_KEYSPACE
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@classmethod
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def _get_column(cls, name):
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"""
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Returns the column matching the given name, raising a key error if
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it doesn't exist
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:param name: the name of the column to return
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:rtype: Column
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"""
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return cls._columns[name]
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def __eq__(self, other):
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if self.__class__ != other.__class__:
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return False
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# check attribute keys
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keys = set(self._columns.keys())
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other_keys = set(self._columns.keys())
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if keys != other_keys:
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return False
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# check that all of the attributes match
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for key in other_keys:
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if getattr(self, key, None) != getattr(other, key, None):
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return False
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return True
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def __ne__(self, other):
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return not self.__eq__(other)
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@classmethod
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def column_family_name(cls, include_keyspace=True):
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"""
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Returns the column family name if it's been defined
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otherwise, it creates it from the module and class name
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"""
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cf_name = ''
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if cls.__table_name__:
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cf_name = cls.__table_name__.lower()
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else:
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# get polymorphic base table names if model is polymorphic
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if cls._is_polymorphic and not cls._is_polymorphic_base:
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return cls._polymorphic_base.column_family_name(include_keyspace=include_keyspace)
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camelcase = re.compile(r'([a-z])([A-Z])')
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ccase = lambda s: camelcase.sub(lambda v: '{}_{}'.format(v.group(1), v.group(2).lower()), s)
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cf_name += ccase(cls.__name__)
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#trim to less than 48 characters or cassandra will complain
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cf_name = cf_name[-48:]
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cf_name = cf_name.lower()
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cf_name = re.sub(r'^_+', '', cf_name)
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if not include_keyspace: return cf_name
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return '{}.{}'.format(cls._get_keyspace(), cf_name)
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def validate(self):
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""" Cleans and validates the field values """
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for name, col in self._columns.items():
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val = col.validate(getattr(self, name))
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setattr(self, name, val)
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def _as_dict(self):
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""" Returns a map of column names to cleaned values """
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values = self._dynamic_columns or {}
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for name, col in self._columns.items():
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values[name] = col.to_database(getattr(self, name, None))
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return values
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@classmethod
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def create(cls, **kwargs):
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extra_columns = set(kwargs.keys()) - set(cls._columns.keys())
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if extra_columns:
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raise ValidationError("Incorrect columns passed: {}".format(extra_columns))
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return cls.objects.create(**kwargs)
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@classmethod
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def all(cls):
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return cls.objects.all()
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@classmethod
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def filter(cls, *args, **kwargs):
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return cls.objects.filter(*args, **kwargs)
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@classmethod
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def get(cls, *args, **kwargs):
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return cls.objects.get(*args, **kwargs)
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def save(self):
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# handle polymorphic models
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if self._is_polymorphic:
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if self._is_polymorphic_base:
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raise PolyMorphicModelException('cannot save polymorphic base model')
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else:
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setattr(self, self._polymorphic_column_name, self.__polymorphic_key__)
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is_new = self.pk is None
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self.validate()
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self.__dmlquery__(self.__class__, self,
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batch=self._batch,
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ttl=self._ttl,
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timestamp=self._timestamp,
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consistency=self.__consistency__).save()
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#reset the value managers
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for v in self._values.values():
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v.reset_previous_value()
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self._is_persisted = True
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self._ttl = None
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self._timestamp = None
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return self
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def update(self, **values):
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for k, v in values.items():
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col = self._columns.get(k)
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# check for nonexistant columns
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if col is None:
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raise ValidationError("{}.{} has no column named: {}".format(self.__module__, self.__class__.__name__, k))
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# check for primary key update attempts
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if col.is_primary_key:
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raise ValidationError("Cannot apply update to primary key '{}' for {}.{}".format(k, self.__module__, self.__class__.__name__))
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setattr(self, k, v)
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# handle polymorphic models
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if self._is_polymorphic:
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if self._is_polymorphic_base:
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raise PolyMorphicModelException('cannot update polymorphic base model')
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else:
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setattr(self, self._polymorphic_column_name, self.__polymorphic_key__)
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self.validate()
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self.__dmlquery__(self.__class__, self,
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batch=self._batch,
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ttl=self._ttl,
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timestamp=self._timestamp,
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consistency=self.__consistency__).update()
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#reset the value managers
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for v in self._values.values():
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v.reset_previous_value()
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self._is_persisted = True
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self._ttl = None
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self._timestamp = None
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return self
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def delete(self):
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""" Deletes this instance """
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self.__dmlquery__(self.__class__, self, batch=self._batch, timestamp=self._timestamp, consistency=self.__consistency__).delete()
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def get_changed_columns(self):
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""" returns a list of the columns that have been updated since instantiation or save """
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return [k for k,v in self._values.items() if v.changed]
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@classmethod
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def _class_batch(cls, batch):
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return cls.objects.batch(batch)
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def _inst_batch(self, batch):
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self._batch = batch
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return self
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batch = hybrid_classmethod(_class_batch, _inst_batch)
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class ModelMetaClass(type):
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def __new__(cls, name, bases, attrs):
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"""
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"""
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#move column definitions into columns dict
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#and set default column names
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column_dict = OrderedDict()
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primary_keys = OrderedDict()
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pk_name = None
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#get inherited properties
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inherited_columns = OrderedDict()
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for base in bases:
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for k,v in getattr(base, '_defined_columns', {}).items():
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inherited_columns.setdefault(k,v)
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#short circuit __abstract__ inheritance
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is_abstract = attrs['__abstract__'] = attrs.get('__abstract__', False)
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#short circuit __polymorphic_key__ inheritance
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attrs['__polymorphic_key__'] = attrs.get('__polymorphic_key__', None)
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def _transform_column(col_name, col_obj):
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column_dict[col_name] = col_obj
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if col_obj.primary_key:
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primary_keys[col_name] = col_obj
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col_obj.set_column_name(col_name)
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#set properties
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attrs[col_name] = ColumnDescriptor(col_obj)
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|
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|
column_definitions = [(k,v) for k,v in attrs.items() if isinstance(v, columns.Column)]
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column_definitions = sorted(column_definitions, lambda x,y: cmp(x[1].position, y[1].position))
|
|
|
|
is_polymorphic_base = any([c[1].polymorphic_key for c in column_definitions])
|
|
|
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column_definitions = inherited_columns.items() + column_definitions
|
|
|
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polymorphic_columns = [c for c in column_definitions if c[1].polymorphic_key]
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|
is_polymorphic = len(polymorphic_columns) > 0
|
|
if len(polymorphic_columns) > 1:
|
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raise ModelDefinitionException('only one polymorphic_key can be defined in a model, {} found'.format(len(polymorphic_columns)))
|
|
|
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polymorphic_column_name, polymorphic_column = polymorphic_columns[0] if polymorphic_columns else (None, None)
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|
|
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if isinstance(polymorphic_column, (columns.BaseContainerColumn, columns.Counter)):
|
|
raise ModelDefinitionException('counter and container columns cannot be used for polymorphic keys')
|
|
|
|
# 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)
|
|
|
|
#TODO: check that the defined columns don't conflict with any of the Model API's existing attributes/methods
|
|
#transform column definitions
|
|
for k, v in column_definitions:
|
|
# 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 = 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
|
|
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['_polymorphic_column'] = polymorphic_column
|
|
attrs['_polymorphic_column_name'] = polymorphic_column_name
|
|
attrs['_polymorphic_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)
|
|
return klass
|
|
|
|
|
|
class Model(BaseModel):
|
|
"""
|
|
the db name for the column family can be set as the attribute db_name, or
|
|
it will be genertaed from the class name
|
|
"""
|
|
__abstract__ = True
|
|
__metaclass__ = ModelMetaClass
|
|
|
|
|