chainsyncer/cic_syncer/db/models/base.py

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2021-02-03 20:55:39 +01:00
# third-party imports
from sqlalchemy import Column, Integer
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker
Model = declarative_base(name='Model')
class SessionBase(Model):
"""The base object for all SQLAlchemy enabled models. All other models must extend this.
"""
__abstract__ = True
id = Column(Integer, primary_key=True)
engine = None
"""Database connection engine of the running aplication"""
sessionmaker = None
"""Factory object responsible for creating sessions from the connection pool"""
transactional = True
"""Whether the database backend supports query transactions. Should be explicitly set by initialization code"""
poolable = True
"""Whether the database backend supports query transactions. Should be explicitly set by initialization code"""
@staticmethod
def create_session():
"""Creates a new database session.
"""
return SessionBase.sessionmaker()
@staticmethod
def _set_engine(engine):
"""Sets the database engine static property
"""
SessionBase.engine = engine
SessionBase.sessionmaker = sessionmaker(bind=SessionBase.engine)
@staticmethod
def connect(dsn, debug=False):
"""Create new database connection engine and connect to database backend.
:param dsn: DSN string defining connection.
:type dsn: str
"""
e = None
if SessionBase.poolable:
e = create_engine(
dsn,
max_overflow=50,
pool_pre_ping=True,
pool_size=20,
pool_recycle=10,
echo=debug,
)
else:
e = create_engine(
dsn,
echo=debug,
)
SessionBase._set_engine(e)
@staticmethod
def disconnect():
"""Disconnect from database and free resources.
"""
SessionBase.engine.dispose()
SessionBase.engine = None