tartiflette-request-sqlalchemy-session 0.9.1

Middleware for the [tartiflette](https://tartiflette.io/) GraphQL server implementation to have a SQLAlchemy Session generated on each server request which is then injected into the resolver context.

Tartiflette Request SQLAlchemy Session

Middleware for the tartiflette GraphQL server implementation to have a SQLAlchemy Session generated on each server request which is then injected into the resolver context.

1. A provided session is unique to the request.
2. A provided session is shared across queries on a request.
3. Must work for queries, mutations, and subscriptions.

Installation

pip install tartiflette-request-sqlalchemy-session[psycopg2]

Currently only supports PostgreSQL through psycopg. Pull requests for other adaptors are welcome.

Configuration

Note: If you have a working project you won't need to change the Alembic configuration. This is mainly useful for a new project.

Alembic configuration

In env.py add:

from tartiflette_request_sa_session import Database

db_config = Database(
    db='db_name',
    engine='db_engine', # e.g. postgres+psycopg2
    host='db_host',
    password='db_password',
    port='db_port',
    user='db_username',
)
database = Database(**db_config)

Update env.py to use:

config = context.config
config.set_main_option('sqlalchemy.url', database.connection_string)

App.py configuration

This configuration will not usually provide an out of the box working example of a tartiflette aiohttp setup. This should be used as guidance to fit into your configuration.

from tartiflette_request_context_hooks import RequestContextHooks, middleware
from tartiflette_request_sa_session import Database,\
    SQLAlchemyRequestContextHooks

def run():
    # As with Alembic add:
    db_manager = Database(
        db='db_name',
        engine='db_engine', # e.g. postgres+psycopg2
        host='db_host',
        password='db_password',
        port='db_port',
        user='db_username',
    )

    # database request-based middleware setup
    sa_hooks = RequestContextHooks(
        context_manager=SQLAlchemyRequestContextHooks(db_manager=db_manager),
        server_middleware=middleware.aiohttp,
    )
    # configure app - tweak to fit own configuration
    app = web.Application(middlewares=[
        sa_hooks.middleware,
    ])
    engine = create_engine(
        sdl=os.path.dirname(os.path.abspath(__file__)) + '/sdl',
        modules=[
            # configure as necessary
        ],
    )

    ctx = {
        'db_session_service': sa_hooks.service,
    }
    web.run_app(
        register_graphql_handlers(
            # ... your other settings ...
            executor_context=ctx,
        )
    )

Use

In your resolver you can now access a new session for each request.

Resolver example: query_resolvers.py

async def resolve_new_request(parent, args, ctx, info):
    session = await ctx['db_session_service']()
    u = session.query(YourModel).filter_by(uuid=args['uuid']).first()
    return u

Notes

1. Currently works using "Tartiflette Request Context Hooks" for middleware handling which only supports aiohttp. Other servers supporting tartiflette could be supported via pull requests on that project.