aa8fb55e87
Initial commit of the event schema for the database. This includes models and alembic migration.
238 lines
7.5 KiB
Python
238 lines
7.5 KiB
Python
from datetime import datetime
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from enum import IntEnum
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from sqlalchemy import event
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from sqlalchemy import literal_column
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from sqlalchemy import Column, Table, ForeignKey, Index, UniqueConstraint
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from sqlalchemy import Float, Boolean, Text, DateTime, Integer, String
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from sqlalchemy import cast, null, case
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from sqlalchemy.orm.interfaces import PropComparator
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from sqlalchemy.ext.hybrid import hybrid_property
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from sqlalchemy.dialects.mysql import DECIMAL
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from sqlalchemy.ext.declarative import declarative_base
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from sqlalchemy.ext.associationproxy import association_proxy
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from sqlalchemy.orm import backref
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from sqlalchemy.orm import relationship
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from sqlalchemy.orm.collections import attribute_mapped_collection
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from sqlalchemy.types import TypeDecorator, DATETIME
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class Datatype(IntEnum):
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none = 0
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string = 1
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int = 2
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float = 3
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datetime = 4
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class PreciseTimestamp(TypeDecorator):
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"""Represents a timestamp precise to the microsecond."""
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impl = DATETIME
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def load_dialect_impl(self, dialect):
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if dialect.name == 'mysql':
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return dialect.type_descriptor(DECIMAL(precision=20,
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scale=6,
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asdecimal=True))
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return dialect.type_descriptor(DATETIME())
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def process_bind_param(self, value, dialect):
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if value is None:
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return value
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elif dialect.name == 'mysql':
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return utils.dt_to_decimal(value)
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return value
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def process_result_value(self, value, dialect):
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if value is None:
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return value
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elif dialect.name == 'mysql':
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return utils.decimal_to_dt(value)
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return value
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class ProxiedDictMixin(object):
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"""Adds obj[name] access to a mapped class.
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This class basically proxies dictionary access to an attribute
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called ``_proxied``. The class which inherits this class
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should have an attribute called ``_proxied`` which points to a dictionary.
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"""
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def __len__(self):
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return len(self._proxied)
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def __iter__(self):
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return iter(self._proxied)
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def __getitem__(self, name):
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return self._proxied[name]
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def __contains__(self, name):
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return name in self._proxied
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def __setitem__(self, name, value):
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self._proxied[name] = value
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def __delitem__(self, name):
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del self._proxied[name]
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class PolymorphicVerticalProperty(object):
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"""A name/value pair with polymorphic value storage."""
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def __init__(self, name, value=None):
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self.name = name
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self.value = value
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@hybrid_property
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def value(self):
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fieldname, discriminator = self.type_map[self.type]
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if fieldname is None:
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return None
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else:
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return getattr(self, fieldname)
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@value.setter
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def value(self, value):
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py_type = type(value)
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fieldname, discriminator = self.type_map[py_type]
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self.type = discriminator
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if fieldname is not None:
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setattr(self, fieldname, value)
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@value.deleter
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def value(self):
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self._set_value(None)
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@value.comparator
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class value(PropComparator):
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"""A comparator for .value, builds a polymorphic comparison via CASE.
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"""
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def __init__(self, cls):
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self.cls = cls
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def _case(self):
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pairs = set(self.cls.type_map.values())
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whens = [
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(
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literal_column("'%s'" % discriminator),
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cast(getattr(self.cls, attribute), String)
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) for attribute, discriminator in pairs
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if attribute is not None
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]
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return case(whens, self.cls.type, null())
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def __eq__(self, other):
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return self._case() == cast(other, String)
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def __ne__(self, other):
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return self._case() != cast(other, String)
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def __repr__(self):
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return '<%s %r=%r>' % (self.__class__.__name__, self.name, self.value)
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@event.listens_for(PolymorphicVerticalProperty, "mapper_configured", propagate=True)
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def on_new_class(mapper, cls_):
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"""Add type lookup info for polymorphic value columns.
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"""
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info_dict = {}
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info_dict[type(None)] = (None, Datatype.none)
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info_dict[Datatype.none] = (None, Datatype.none)
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for k in mapper.c.keys():
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col = mapper.c[k]
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if 'type' in col.info:
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python_type, discriminator = col.info['type']
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info_dict[python_type] = (k, discriminator)
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info_dict[discriminator] = (k, discriminator)
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cls_.type_map = info_dict
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Base = declarative_base()
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class Trait(PolymorphicVerticalProperty, Base):
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__tablename__ = 'trait'
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__table_args__ = (
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Index('ix_trait_t_int', 't_int'),
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Index('ix_trait_t_string', 't_string'),
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Index('ix_trait_t_datetime', 't_datetime'),
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Index('ix_trait_t_float', 't_float'),
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)
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event_id = Column(Integer, ForeignKey('event.id'), primary_key=True)
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name = Column(String(100), primary_key=True)
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type = Column(Integer)
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t_string = Column(String(255), info=dict(type=(str, Datatype.string)),
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nullable=True, default=None)
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t_float = Column(Float, info=dict(type=(float, Datatype.float)),
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nullable=True, default=None)
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t_int = Column(Integer, info=dict(type=(int, Datatype.int)),
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nullable=True, default=None)
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t_datetime = Column(PreciseTimestamp(), info=dict(type=(datetime, Datatype.datetime)),
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nullable=True, default=None)
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def __repr__(self):
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return "<Trait(%s) %s=%s/%s/%s/%s on %s>" % (self.name,
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self.type,
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self.t_string,
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self.t_float,
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self.t_int,
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self.t_datetime,
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self.event_id)
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class EventType(Base):
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"""Types of event records."""
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__tablename__ = 'event_type'
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id = Column(Integer, primary_key=True)
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desc = Column(String(255), unique=True)
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def __init__(self, event_type):
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self.desc = event_type
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def __repr__(self):
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return "<EventType: %s>" % self.desc
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class Event(ProxiedDictMixin, Base):
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__tablename__ = 'event'
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__table_args__ = (
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Index('ix_event_message_id', 'message_id'),
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Index('ix_event_type_id', 'event_type_id'),
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Index('ix_event_generated', 'generated')
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)
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id = Column(Integer, primary_key=True)
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message_id = Column(String(50), unique=True)
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generated = Column(PreciseTimestamp())
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event_type_id = Column(Integer, ForeignKey('event_type.id'))
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event_type = relationship("EventType", backref=backref('event_type'))
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traits = relationship("Trait",
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collection_class=attribute_mapped_collection('name'))
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_proxied = association_proxy("traits", "value",
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creator=lambda name, value: Trait(name=name, value=value))
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def __init__(self, message_id, event_type, generated):
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self.message_id = message_id
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self.event_type = event_type
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self.generated = generated
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def __repr__(self):
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return "<Event %s ('Event: %s %s, Generated: %s')>" % (self.id,
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self.message_id,
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self.event_type,
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self.generated)
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