The Simple Thread-local Session Maker

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SQLAlchemy-Rope provides simple thread-local session maker for SQLAlchemy. Github – Simple example

I recommend to use sqlalchemy.orm.scoping.scoped_session explicitly. There is some possibility of SessionJenny dirty your code. This library is only for lazy people just like me.

Instllation

Install with pip:

$pip install sqlalchemy_rope

Configuring Application

make instance of SessionJenny with sessionmaker

from sqlalchemy import Integer, Column
from sqlalchemy.orm.session import sessionmaker
import sqlalchemy.ext.declarative

from sqlalchemy_rope import SessionJenny

Base = sqlalchemy.ext.declarative.declarative_base()

url = "sqlite:///database.db"


class Data(Base):
    __tablename__ = "database"
    id = Column(Integer, primary_key=True)


engine = sqlalchemy.create_engine(url)
Base.metadata.create_all(engine)
SessionMaker = sessionmaker(bind=engine)

jenny = SessionJenny(SessionMaker)

How It Works

Making SessionRope

You can access Session object with SessionJenny().session

data = Data()

jenny.session.add(data)
jenny.session.commit()

SessionJenny object make SessionRope object when you call or use attribute of SessionJenny.rope

And SessionJenny.session returns SessionJenny.rope.session, So using SessionJenny.session also makes SessionRope object.

Where the SessionRope object go? It’s set as the local variable of first outer scope of SessionJenny automatically. variable’s name will be the return value of SessionJenny.create_rope_name()

If you want to set explicitly, call SessionJenny.set_rope(frame=None). if frame is given, SessionRope will be set as local variable of frame, or not, set as the local variable of first outer scope of SessionJenny.

Calling SessionRope

SessionJenny object has _ropes attribute. This is WeakValueDictionary which key is SessionJenny.create_rope_name(), value is SessionRope made by using SessionJenny.rope or SessionJenny.session.

Every time you use SessionJenny.rope or SessionJenny.session, SessionJenny will make SessionRope if there is no SessionJenny object stored in SessionJenny._ropes which key is SessionJenny.create_rope_name().

Exiting Scope

SessionJenny object make SessionRope object as local variable. So, when exiting scope(finish running function/generator/coroutine), SessionRope object will be deleted.

SessionRope object run SessionRope.remove() which is same as SQLAlchemy.orm.scoping.scoped_session.remove().

Documentation

SessionJenny(session_factory, scopefunc=None)

Initialize SessionJenny. All arguments will be passed to SQLAlchemy.orm.scoping.scoped_session

SessionJenny._rope_name_callback

settable callback returns str which will be SessionRope variable’s name. This has to be callable. Default is None

SessionJenny.set_rope(frame=None)

Create SessionRope object and set as local variable to frame.f_locals if frame is provided. Otherwise, first outer scope of SessionJenny.

SessionJenny.rope

Create SessionRope object and set as local variable to first outer scope of SessionJenny if there is no SessionJenny object stored in SessionJenny._ropes which key is SessionJenny.create_rope_name(). And return SessionRope object.

SessionJenny.session

Return SessionJenny.rope.session

SessionJenny.remove(rope_name=None)

Do as SQLAlchemy.orm.scoping.scoped_session.remove(). And remove data stored in SessionJenny._ropes which key is rope_name if rope_name provided. Otherwise, SessionJenny._ropes which key is SessionJenny.create_rope_name() will be deleted.

SessionRope(registry)

In usual use, I recommend to use SessionJenny, not SessionRope. But if you want to create SessionRope explicitly, Use this. register must be an instance of ScopedRegistry or ThreadLocalRegistry

SessionRope.session

Return self.registry()

SessionRope.remove()

Do as SQLAlchemy.orm.scoping.scoped_session.remove().

Usage Example

import responder

from sqlalchemy import Integer, Column
from sqlalchemy.orm.session import sessionmaker
import sqlalchemy.ext.declarative

from sqlalchemy_rope import SessionJenny

api = responder.API()
Base = sqlalchemy.ext.declarative.declarative_base()

url = "sqlite:///data.db"


class Data(Base):
    __tablename__ = "data"
    id = Column(Integer, primary_key=True)
    count = Column(Integer, default=0)


engine = sqlalchemy.create_engine(url, echo=False)
Base.metadata.create_all(engine)
SessionMaker = sessionmaker(bind=engine)

jenny = SessionJenny(SessionMaker)

if not jenny.session.query(Data).all():
    data = Data()
    jenny.session.add(data)
    jenny.session.commit()


@api.route("/")
def index(req, resp):
    data = jenny.session.query(Data).first()
    data.count += 1
    jenny.session.commit()
    resp.content = str(data.count)


def session_id():
    return id(jenny.session)


if __name__ == "__main__":
    api.run()

Indices and tables

• Index
• Module Index
• Search Page

In End

Sorry for my poor English. I want you to join us and send many pull requests about Doc, code, features and more!!