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.
- A provided session is unique to the request.
- A provided session is shared across queries on a request.
- 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 uNotes
- 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.
