We are using sqlalchemy's autoload feature to do column mapping to prevent hardcoding in our code.
class users(Base):
__tablename__ = 'users'
__table_args__ = {
'autoload': True,
'mysql_engine': 'InnoDB',
'mysql_charset': 'utf8'
}
Is there a way to serialize or cache autoloaded metadata/orms so we don't have to go through the autoload process every time we need to reference our orm classes from other scripts/functions?
I have looked at beaker caching and pickle but haven't found a clear answer if it is possible or how to do it.
Ideally we run the autload mapping script only when we have committed changes to our database structure but reference a non-autoload/persistent/cached version of our database mapping from all other scripts/functions,
Any ideas?
What I am doing now is to pickle the metadata after running the reflection through a database connection (MySQL) and once a pickle is available use that pickled metadata to reflect on the schema with the metadata bound to an SQLite engine.
cachefile='orm.p'
dbfile='database'
engine_dev = create_engine(#db connect, echo=True)
engine_meta = create_engine('sqlite:///%s' % dbfile,echo=True)
Base = declarative_base()
Base.metadata.bind = engine_dev
metadata = MetaData(bind=engine_dev)
# load from pickle
try:
with open(cachefile, 'r') as cache:
metadata2 = pickle.load(cache)
metadata2.bind = engine_meta
cache.close()
class Users(Base):
__table__ = Table('users', metadata2, autoload=True)
print "ORM loaded from pickle"
# if no pickle, use reflect through database connection
except:
class Users(Base):
__table__ = Table('users', metadata, autoload=True)
print "ORM through database autoload"
# create metapickle
metadata.create_all()
with open(cachefile, 'w') as cache:
pickle.dump(metadata, cache)
cache.close()
Any comments if this is alright (it works) or there is something I can improve?
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