110 lines
3.2 KiB
Python
110 lines
3.2 KiB
Python
from datetime import datetime
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from uuid import uuid1
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from cqlengine.exceptions import ValidationError
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class QueryValue(object):
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"""
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Base class for query filter values. Subclasses of these classes can
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be passed into .filter() keyword args
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"""
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_cql_string = ':{}'
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def __init__(self, value, identifier=None):
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self.value = value
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self.identifier = uuid1().hex if identifier is None else identifier
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def get_cql(self):
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return self._cql_string.format(self.identifier)
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def get_value(self):
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return self.value
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def get_dict(self, column):
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return {self.identifier: column.to_database(self.get_value())}
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@property
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def cql(self):
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return self.get_cql()
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class BaseQueryFunction(QueryValue):
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"""
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Base class for filtering functions. Subclasses of these classes can
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be passed into .filter() and will be translated into CQL functions in
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the resulting query
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"""
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class MinTimeUUID(BaseQueryFunction):
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"""
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return a fake timeuuid corresponding to the smallest possible timeuuid for the given timestamp
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http://cassandra.apache.org/doc/cql3/CQL.html#timeuuidFun
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"""
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_cql_string = 'MinTimeUUID(:{})'
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def __init__(self, value):
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"""
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:param value: the time to create a maximum time uuid from
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:type value: datetime
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"""
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if not isinstance(value, datetime):
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raise ValidationError('datetime instance is required')
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super(MinTimeUUID, self).__init__(value)
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def get_value(self):
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epoch = datetime(1970, 1, 1)
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return long((self.value - epoch).total_seconds() * 1000)
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def get_dict(self, column):
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return {self.identifier: self.get_value()}
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class MaxTimeUUID(BaseQueryFunction):
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"""
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return a fake timeuuid corresponding to the largest possible timeuuid for the given timestamp
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http://cassandra.apache.org/doc/cql3/CQL.html#timeuuidFun
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"""
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_cql_string = 'MaxTimeUUID(:{})'
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def __init__(self, value):
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"""
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:param value: the time to create a minimum time uuid from
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:type value: datetime
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"""
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if not isinstance(value, datetime):
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raise ValidationError('datetime instance is required')
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super(MaxTimeUUID, self).__init__(value)
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def get_value(self):
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epoch = datetime(1970, 1, 1)
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return long((self.value - epoch).total_seconds() * 1000)
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def get_dict(self, column):
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return {self.identifier: self.get_value()}
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class Token(BaseQueryFunction):
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"""
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compute the token for a given partition key
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http://cassandra.apache.org/doc/cql3/CQL.html#tokenFun
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"""
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def __init__(self, *values):
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if len(values) == 1 and isinstance(values[0], (list, tuple)):
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values = values[0]
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super(Token, self).__init__(values, [uuid1().hex for i in values])
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def get_dict(self, column):
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items = zip(self.identifier, self.value, column.partition_columns)
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return dict(
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(id, col.to_database(val)) for id, val, col in items
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)
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def get_cql(self):
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token_args = ', '.join(':{}'.format(id) for id in self.identifier)
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return "token({})".format(token_args)
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