74 lines
2.1 KiB
Python
74 lines
2.1 KiB
Python
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# third-party imports
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from sqlalchemy import Column, Integer
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from sqlalchemy.ext.declarative import declarative_base
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from sqlalchemy import create_engine
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from sqlalchemy.orm import sessionmaker
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Model = declarative_base(name='Model')
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class SessionBase(Model):
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"""The base object for all SQLAlchemy enabled models. All other models must extend this.
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"""
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__abstract__ = True
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id = Column(Integer, primary_key=True)
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engine = None
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"""Database connection engine of the running aplication"""
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sessionmaker = None
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"""Factory object responsible for creating sessions from the connection pool"""
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transactional = True
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"""Whether the database backend supports query transactions. Should be explicitly set by initialization code"""
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poolable = True
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"""Whether the database backend supports query transactions. Should be explicitly set by initialization code"""
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@staticmethod
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def create_session():
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"""Creates a new database session.
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"""
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return SessionBase.sessionmaker()
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@staticmethod
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def _set_engine(engine):
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"""Sets the database engine static property
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"""
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SessionBase.engine = engine
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SessionBase.sessionmaker = sessionmaker(bind=SessionBase.engine)
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@staticmethod
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def connect(dsn, debug=False):
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"""Create new database connection engine and connect to database backend.
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:param dsn: DSN string defining connection.
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:type dsn: str
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"""
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e = None
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if SessionBase.poolable:
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e = create_engine(
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dsn,
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max_overflow=50,
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pool_pre_ping=True,
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pool_size=20,
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pool_recycle=10,
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echo=debug,
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)
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else:
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e = create_engine(
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dsn,
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echo=debug,
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)
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SessionBase._set_engine(e)
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@staticmethod
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def disconnect():
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"""Disconnect from database and free resources.
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"""
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SessionBase.engine.dispose()
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SessionBase.engine = None
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