Source code for cassandra.cqlengine.columns

# Copyright 2013-2016 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 copy import deepcopy, copy
from datetime import date, datetime, timedelta
import logging
import six
from uuid import UUID as _UUID

from cassandra import util
from cassandra.cqltypes import SimpleDateType, _cqltypes, UserType
from cassandra.cqlengine import ValidationError
from cassandra.cqlengine.functions import get_total_seconds

log = logging.getLogger(__name__)


class BaseValueManager(object):

    def __init__(self, instance, column, value):
        self.instance = instance
        self.column = column
        self.value = value
        self.previous_value = None
        self.explicit = False

    @property
    def deleted(self):
        return self.column._val_is_null(self.value) and (self.explicit or self.previous_value is not None)

    @property
    def changed(self):
        """
        Indicates whether or not this value has changed.

        :rtype: boolean

        """
        return self.value != self.previous_value

    def reset_previous_value(self):
        self.previous_value = deepcopy(self.value)

    def getval(self):
        return self.value

    def setval(self, val):
        self.value = val

    def delval(self):
        self.value = None

    def get_property(self):
        _get = lambda slf: self.getval()
        _set = lambda slf, val: self.setval(val)
        _del = lambda slf: self.delval()

        if self.column.can_delete:
            return property(_get, _set, _del)
        else:
            return property(_get, _set)


[docs]class Column(object): # the cassandra type this column maps to db_type = None value_manager = BaseValueManager instance_counter = 0 _python_type_hashable = True primary_key = False """ bool flag, indicates this column is a primary key. The first primary key defined on a model is the partition key (unless partition keys are set), all others are cluster keys """ partition_key = False """ indicates that this column should be the partition key, defining more than one partition key column creates a compound partition key """ index = False """ bool flag, indicates an index should be created for this column """ db_field = None """ the fieldname this field will map to in the database """ default = None """ the default value, can be a value or a callable (no args) """ required = False """ boolean, is the field required? Model validation will raise and exception if required is set to True and there is a None value assigned """ clustering_order = None """ only applicable on clustering keys (primary keys that are not partition keys) determines the order that the clustering keys are sorted on disk """ discriminator_column = False """ boolean, if set to True, this column will be used for discriminating records of inherited models. Should only be set on a column of an abstract model being used for inheritance. There may only be one discriminator column per model. See :attr:`~.__discriminator_value__` for how to specify the value of this column on specialized models. """ static = False """ boolean, if set to True, this is a static column, with a single value per partition """ def __init__(self, primary_key=False, partition_key=False, index=False, db_field=None, default=None, required=False, clustering_order=None, discriminator_column=False, static=False): self.partition_key = partition_key self.primary_key = partition_key or primary_key self.index = index self.db_field = db_field self.default = default self.required = required self.clustering_order = clustering_order self.discriminator_column = discriminator_column # the column name in the model definition self.column_name = None self._partition_key_index = None self.static = static self.value = None # keep track of instantiation order self.position = Column.instance_counter Column.instance_counter += 1 def validate(self, value): """ Returns a cleaned and validated value. Raises a ValidationError if there's a problem """ if value is None: if self.required: raise ValidationError('{0} - None values are not allowed'.format(self.column_name or self.db_field)) return value def to_python(self, value): """ Converts data from the database into python values raises a ValidationError if the value can't be converted """ return value def to_database(self, value): """ Converts python value into database value """ if value is None and self.has_default: return self.get_default() return value @property def has_default(self): return self.default is not None @property def is_primary_key(self): return self.primary_key @property def can_delete(self): return not self.primary_key def get_default(self): if self.has_default: if callable(self.default): return self.default() else: return self.default def get_column_def(self): """ Returns a column definition for CQL table definition """ static = "static" if self.static else "" return '{0} {1} {2}'.format(self.cql, self.db_type, static) # TODO: make columns use cqltypes under the hood # until then, this bridges the gap in using types along with cassandra.metadata for CQL generation def cql_parameterized_type(self): return self.db_type def set_column_name(self, name): """ Sets the column name during document class construction This value will be ignored if db_field is set in __init__ """ self.column_name = name @property def db_field_name(self): """ Returns the name of the cql name of this column """ return self.db_field or self.column_name @property def db_index_name(self): """ Returns the name of the cql index """ return 'index_{0}'.format(self.db_field_name) @property def cql(self): return self.get_cql() def get_cql(self): return '"{0}"'.format(self.db_field_name) def _val_is_null(self, val): """ determines if the given value equates to a null value for the given column type """ return val is None @property def sub_types(self): return [] @property def cql_type(self): return _cqltypes[self.db_type]
[docs]class Blob(Column): """ Stores a raw binary value """ db_type = 'blob' def to_database(self, value): if not isinstance(value, (six.binary_type, bytearray)): raise Exception("expecting a binary, got a %s" % type(value)) val = super(Bytes, self).to_database(value) return bytearray(val)
Bytes = Blob
[docs]class Ascii(Column): """ Stores a US-ASCII character string """ db_type = 'ascii'
class Inet(Column): """ Stores an IP address in IPv4 or IPv6 format """ db_type = 'inet'
[docs]class Text(Column): """ Stores a UTF-8 encoded string """ db_type = 'text' def __init__(self, min_length=None, max_length=None, **kwargs): """ :param int min_length: Sets the minimum length of this string, for validation purposes. Defaults to 1 if this is a ``required`` column. Otherwise, None. :param int max_length: Sets the maximum length of this string, for validation purposes. """ self.min_length = min_length or (1 if kwargs.get('required', False) else None) self.max_length = max_length super(Text, self).__init__(**kwargs) def validate(self, value): value = super(Text, self).validate(value) if value is None: return if not isinstance(value, (six.string_types, bytearray)) and value is not None: raise ValidationError('{0} {1} is not a string'.format(self.column_name, type(value))) if self.max_length: if len(value) > self.max_length: raise ValidationError('{0} is longer than {1} characters'.format(self.column_name, self.max_length)) if self.min_length: if len(value) < self.min_length: raise ValidationError('{0} is shorter than {1} characters'.format(self.column_name, self.min_length)) return value
[docs]class Integer(Column): """ Stores a 32-bit signed integer value """ db_type = 'int' def validate(self, value): val = super(Integer, self).validate(value) if val is None: return try: return int(val) except (TypeError, ValueError): raise ValidationError("{0} {1} can't be converted to integral value".format(self.column_name, value)) def to_python(self, value): return self.validate(value) def to_database(self, value): return self.validate(value)
[docs]class TinyInt(Integer): """ Stores an 8-bit signed integer value .. versionadded:: 2.6.0 requires C* 2.2+ and protocol v4+ """ db_type = 'tinyint'
[docs]class SmallInt(Integer): """ Stores a 16-bit signed integer value .. versionadded:: 2.6.0 requires C* 2.2+ and protocol v4+ """ db_type = 'smallint'
[docs]class BigInt(Integer): """ Stores a 64-bit signed integer value """ db_type = 'bigint'
[docs]class VarInt(Column): """ Stores an arbitrary-precision integer """ db_type = 'varint' def validate(self, value): val = super(VarInt, self).validate(value) if val is None: return try: return int(val) except (TypeError, ValueError): raise ValidationError( "{0} {1} can't be converted to integral value".format(self.column_name, value)) def to_python(self, value): return self.validate(value) def to_database(self, value): return self.validate(value)
class CounterValueManager(BaseValueManager): def __init__(self, instance, column, value): super(CounterValueManager, self).__init__(instance, column, value) self.value = self.value or 0 self.previous_value = self.previous_value or 0
[docs]class Counter(Integer): """ Stores a counter that can be inremented and decremented """ db_type = 'counter' value_manager = CounterValueManager def __init__(self, index=False, db_field=None, required=False): super(Counter, self).__init__( primary_key=False, partition_key=False, index=index, db_field=db_field, default=0, required=required, )
[docs]class DateTime(Column): """ Stores a datetime value """ db_type = 'timestamp' truncate_microseconds = False """ Set this ``True`` to have model instances truncate the date, quantizing it in the same way it will be in the database. This allows equality comparison between assigned values and values read back from the database:: DateTime.truncate_microseconds = True assert Model.create(id=0, d=datetime.utcnow()) == Model.objects(id=0).first() Defaults to ``False`` to preserve legacy behavior. May change in the future. """ def to_python(self, value): if value is None: return if isinstance(value, datetime): if DateTime.truncate_microseconds: us = value.microsecond truncated_us = us // 1000 * 1000 return value - timedelta(microseconds=us - truncated_us) else: return value elif isinstance(value, date): return datetime(*(value.timetuple()[:6])) return datetime.utcfromtimestamp(value) def to_database(self, value): value = super(DateTime, self).to_database(value) if value is None: return if not isinstance(value, datetime): if isinstance(value, date): value = datetime(value.year, value.month, value.day) else: raise ValidationError("{0} '{1}' is not a datetime object".format(self.column_name, value)) epoch = datetime(1970, 1, 1, tzinfo=value.tzinfo) offset = get_total_seconds(epoch.tzinfo.utcoffset(epoch)) if epoch.tzinfo else 0 return int((get_total_seconds(value - epoch) - offset) * 1000)
[docs]class Date(Column): """ Stores a simple date, with no time-of-day .. versionchanged:: 2.6.0 removed overload of Date and DateTime. DateTime is a drop-in replacement for legacy models requires C* 2.2+ and protocol v4+ """ db_type = 'date' def to_database(self, value): value = super(Date, self).to_database(value) if value is None: return # need to translate to int version because some dates are not representable in # string form (datetime limitation) d = value if isinstance(value, util.Date) else util.Date(value) return d.days_from_epoch + SimpleDateType.EPOCH_OFFSET_DAYS
[docs]class Time(Column): """ Stores a timezone-naive time-of-day, with nanosecond precision .. versionadded:: 2.6.0 requires C* 2.2+ and protocol v4+ """ db_type = 'time' def to_database(self, value): value = super(Time, self).to_database(value) if value is None: return # str(util.Time) yields desired CQL encoding return value if isinstance(value, util.Time) else util.Time(value)
[docs]class UUID(Column): """ Stores a type 1 or 4 UUID """ db_type = 'uuid' def validate(self, value): val = super(UUID, self).validate(value) if val is None: return if isinstance(val, _UUID): return val if isinstance(val, six.string_types): try: return _UUID(val) except ValueError: # fall-through to error pass raise ValidationError("{0} {1} is not a valid uuid".format( self.column_name, value)) def to_python(self, value): return self.validate(value) def to_database(self, value): return self.validate(value)
[docs]class TimeUUID(UUID): """ UUID containing timestamp """ db_type = 'timeuuid'
[docs]class Boolean(Column): """ Stores a boolean True or False value """ db_type = 'boolean' def validate(self, value): """ Always returns a Python boolean. """ value = super(Boolean, self).validate(value) if value is not None: value = bool(value) return value def to_python(self, value): return self.validate(value)
class BaseFloat(Column): def validate(self, value): value = super(BaseFloat, self).validate(value) if value is None: return try: return float(value) except (TypeError, ValueError): raise ValidationError("{0} {1} is not a valid float".format(self.column_name, value)) def to_python(self, value): return self.validate(value) def to_database(self, value): return self.validate(value)
[docs]class Float(BaseFloat): """ Stores a single-precision floating-point value """ db_type = 'float'
[docs]class Double(BaseFloat): """ Stores a double-precision floating-point value """ db_type = 'double'
[docs]class Decimal(Column): """ Stores a variable precision decimal value """ db_type = 'decimal' def validate(self, value): from decimal import Decimal as _Decimal from decimal import InvalidOperation val = super(Decimal, self).validate(value) if val is None: return try: return _Decimal(repr(val)) if isinstance(val, float) else _Decimal(val) except InvalidOperation: raise ValidationError("{0} '{1}' can't be coerced to decimal".format(self.column_name, val)) def to_python(self, value): return self.validate(value) def to_database(self, value): return self.validate(value)
class BaseCollectionColumn(Column): """ Base Container type for collection-like columns. https://cassandra.apache.org/doc/cql3/CQL.html#collections """ def __init__(self, types, **kwargs): """ :param types: a sequence of sub types in this collection """ instances = [] for t in types: inheritance_comparator = issubclass if isinstance(t, type) else isinstance if not inheritance_comparator(t, Column): raise ValidationError("%s is not a column class" % (t,)) if t.db_type is None: raise ValidationError("%s is an abstract type" % (t,)) inst = t() if isinstance(t, type) else t if isinstance(t, BaseCollectionColumn): inst._freeze_db_type() instances.append(inst) self.types = instances super(BaseCollectionColumn, self).__init__(**kwargs) def validate(self, value): value = super(BaseCollectionColumn, self).validate(value) # It is dangerous to let collections have more than 65535. # See: https://issues.apache.org/jira/browse/CASSANDRA-5428 if value is not None and len(value) > 65535: raise ValidationError("{0} Collection can't have more than 65535 elements.".format(self.column_name)) return value def _val_is_null(self, val): return not val def _freeze_db_type(self): if not self.db_type.startswith('frozen'): self.db_type = "frozen<%s>" % (self.db_type,) @property def sub_types(self): return self.types @property def cql_type(self): return _cqltypes[self.__class__.__name__.lower()].apply_parameters([c.cql_type for c in self.types]) class Tuple(BaseCollectionColumn): """ Stores a fixed-length set of positional values http://docs.datastax.com/en/cql/3.1/cql/cql_reference/tupleType.html """ def __init__(self, *args, **kwargs): """ :param args: column types representing tuple composition """ if not args: raise ValueError("Tuple must specify at least one inner type") super(Tuple, self).__init__(args, **kwargs) self.db_type = 'tuple<{0}>'.format(', '.join(typ.db_type for typ in self.types)) def validate(self, value): val = super(Tuple, self).validate(value) if val is None: return if len(val) > len(self.types): raise ValidationError("Value %r has more fields than tuple definition (%s)" % (val, ', '.join(t for t in self.types))) return tuple(t.validate(v) for t, v in zip(self.types, val)) def to_python(self, value): if value is None: return tuple() return tuple(t.to_python(v) for t, v in zip(self.types, value)) def to_database(self, value): if value is None: return return tuple(t.to_database(v) for t, v in zip(self.types, value)) class BaseContainerColumn(BaseCollectionColumn): pass
[docs]class Set(BaseContainerColumn): """ Stores a set of unordered, unique values http://www.datastax.com/documentation/cql/3.1/cql/cql_using/use_set_t.html """ _python_type_hashable = False def __init__(self, value_type, strict=True, default=set, **kwargs): """ :param value_type: a column class indicating the types of the value :param strict: sets whether non set values will be coerced to set type on validation, or raise a validation error, defaults to True """ self.strict = strict super(Set, self).__init__((value_type,), default=default, **kwargs) self.value_col = self.types[0] if not self.value_col._python_type_hashable: raise ValidationError("Cannot create a Set with unhashable value type (see PYTHON-494)") self.db_type = 'set<{0}>'.format(self.value_col.db_type) def validate(self, value): val = super(Set, self).validate(value) if val is None: return types = (set, util.SortedSet) if self.strict else (set, util.SortedSet, list, tuple) if not isinstance(val, types): if self.strict: raise ValidationError('{0} {1} is not a set object'.format(self.column_name, val)) else: raise ValidationError('{0} {1} cannot be coerced to a set object'.format(self.column_name, val)) if None in val: raise ValidationError("{0} None not allowed in a set".format(self.column_name)) # TODO: stop doing this conversion because it doesn't support non-hashable collections as keys (cassandra does) # will need to start using the cassandra.util types in the next major rev (PYTHON-494) return set(self.value_col.validate(v) for v in val) def to_python(self, value): if value is None: return set() return set(self.value_col.to_python(v) for v in value) def to_database(self, value): if value is None: return None return set(self.value_col.to_database(v) for v in value)
[docs]class List(BaseContainerColumn): """ Stores a list of ordered values http://www.datastax.com/documentation/cql/3.1/cql/cql_using/use_list_t.html """ _python_type_hashable = False def __init__(self, value_type, default=list, **kwargs): """ :param value_type: a column class indicating the types of the value """ super(List, self).__init__((value_type,), default=default, **kwargs) self.value_col = self.types[0] self.db_type = 'list<{0}>'.format(self.value_col.db_type) def validate(self, value): val = super(List, self).validate(value) if val is None: return if not isinstance(val, (set, list, tuple)): raise ValidationError('{0} {1} is not a list object'.format(self.column_name, val)) if None in val: raise ValidationError("{0} None is not allowed in a list".format(self.column_name)) return [self.value_col.validate(v) for v in val] def to_python(self, value): if value is None: return [] return [self.value_col.to_python(v) for v in value] def to_database(self, value): if value is None: return None return [self.value_col.to_database(v) for v in value]
[docs]class Map(BaseContainerColumn): """ Stores a key -> value map (dictionary) http://www.datastax.com/documentation/cql/3.1/cql/cql_using/use_map_t.html """ _python_type_hashable = False def __init__(self, key_type, value_type, default=dict, **kwargs): """ :param key_type: a column class indicating the types of the key :param value_type: a column class indicating the types of the value """ super(Map, self).__init__((key_type, value_type), default=default, **kwargs) self.key_col = self.types[0] self.value_col = self.types[1] if not self.key_col._python_type_hashable: raise ValidationError("Cannot create a Map with unhashable key type (see PYTHON-494)") self.db_type = 'map<{0}, {1}>'.format(self.key_col.db_type, self.value_col.db_type) def validate(self, value): val = super(Map, self).validate(value) if val is None: return if not isinstance(val, (dict, util.OrderedMap)): raise ValidationError('{0} {1} is not a dict object'.format(self.column_name, val)) if None in val: raise ValidationError("{0} None is not allowed in a map".format(self.column_name)) # TODO: stop doing this conversion because it doesn't support non-hashable collections as keys (cassandra does) # will need to start using the cassandra.util types in the next major rev (PYTHON-494) return dict((self.key_col.validate(k), self.value_col.validate(v)) for k, v in val.items()) def to_python(self, value): if value is None: return {} if value is not None: return dict((self.key_col.to_python(k), self.value_col.to_python(v)) for k, v in value.items()) def to_database(self, value): if value is None: return None return dict((self.key_col.to_database(k), self.value_col.to_database(v)) for k, v in value.items())
class UDTValueManager(BaseValueManager): @property def changed(self): return self.value != self.previous_value or (self.value is not None and self.value.has_changed_fields()) def reset_previous_value(self): if self.value is not None: self.value.reset_changed_fields() self.previous_value = copy(self.value)
[docs]class UserDefinedType(Column): """ User Defined Type column http://www.datastax.com/documentation/cql/3.1/cql/cql_using/cqlUseUDT.html These columns are represented by a specialization of :class:`cassandra.cqlengine.usertype.UserType`. Please see :ref:`user_types` for examples and discussion. """ value_manager = UDTValueManager def __init__(self, user_type, **kwargs): """ :param type user_type: specifies the :class:`~.cqlengine.usertype.UserType` model of the column """ self.user_type = user_type self.db_type = "frozen<%s>" % user_type.type_name() super(UserDefinedType, self).__init__(**kwargs) @property def sub_types(self): return list(self.user_type._fields.values()) @property def cql_type(self): return UserType.make_udt_class(keyspace='', udt_name=self.user_type.type_name(), field_names=[c.db_field_name for c in self.user_type._fields.values()], field_types=[c.cql_type for c in self.user_type._fields.values()])
def resolve_udts(col_def, out_list): for col in col_def.sub_types: resolve_udts(col, out_list) if isinstance(col_def, UserDefinedType): out_list.append(col_def.user_type) class _PartitionKeysToken(Column): """ virtual column representing token of partition columns. Used by filter(pk__token=Token(...)) filters """ def __init__(self, model): self.partition_columns = model._partition_keys.values() super(_PartitionKeysToken, self).__init__(partition_key=True) @property def db_field_name(self): return 'token({0})'.format(', '.join(['"{0}"'.format(c.db_field_name) for c in self.partition_columns]))