SQLAlchemy¶

FastAPI Users provides the necessary tools to work with SQL databases thanks to SQLAlchemy Core and encode/databases package for full async support.

Installation¶

Install the database driver that corresponds to your DBMS:

pip install 'databases[postgresql]'

pip install 'databases[mysql]'

pip install 'databases[sqlite]'

For the sake of this tutorial from now on, we'll use a simple SQLite databse.

Setup User table¶

Let's declare our SQLAlchemy User table.

import databases
import sqlalchemy
from fastapi_users.db import SQLAlchemyBaseUserTable, SQLAlchemyUserDatabase
from sqlalchemy.ext.declarative import DeclarativeMeta, declarative_base

from .models import UserDB

DATABASE_URL = "sqlite:///./test.db"
database = databases.Database(DATABASE_URL)
Base: DeclarativeMeta = declarative_base()


class UserTable(Base, SQLAlchemyBaseUserTable):
    pass


engine = sqlalchemy.create_engine(
    DATABASE_URL, connect_args={"check_same_thread": False}
)
Base.metadata.create_all(engine)

users = UserTable.__table__


def get_user_db():
    yield SQLAlchemyUserDatabase(UserDB, database, users)

As you can see, FastAPI Users provides a mixin that will include base fields for our User table. You can of course add you own fields there to fit to your needs!

Create the tables¶

We'll now create an SQLAlchemy engine and ask it to create all the defined tables.

import databases
import sqlalchemy
from fastapi_users.db import SQLAlchemyBaseUserTable, SQLAlchemyUserDatabase
from sqlalchemy.ext.declarative import DeclarativeMeta, declarative_base

from .models import UserDB

DATABASE_URL = "sqlite:///./test.db"
database = databases.Database(DATABASE_URL)
Base: DeclarativeMeta = declarative_base()


class UserTable(Base, SQLAlchemyBaseUserTable):
    pass


engine = sqlalchemy.create_engine(
    DATABASE_URL, connect_args={"check_same_thread": False}
)
Base.metadata.create_all(engine)

users = UserTable.__table__


def get_user_db():
    yield SQLAlchemyUserDatabase(UserDB, database, users)

Warning

In production, it's strongly recommended to setup a migration system to update your SQL schemas. See Alembic.

Create the database adapter dependency¶

The database adapter of FastAPI Users makes the link between your database configuration and the users logic. It should be generated by a FastAPI dependency.

import databases
import sqlalchemy
from fastapi_users.db import SQLAlchemyBaseUserTable, SQLAlchemyUserDatabase
from sqlalchemy.ext.declarative import DeclarativeMeta, declarative_base

from .models import UserDB

DATABASE_URL = "sqlite:///./test.db"
database = databases.Database(DATABASE_URL)
Base: DeclarativeMeta = declarative_base()


class UserTable(Base, SQLAlchemyBaseUserTable):
    pass


engine = sqlalchemy.create_engine(
    DATABASE_URL, connect_args={"check_same_thread": False}
)
Base.metadata.create_all(engine)

users = UserTable.__table__


def get_user_db():
    yield SQLAlchemyUserDatabase(UserDB, database, users)

Notice that we pass it three things:

A reference to your UserDB model.
A database instance, which allows us to do asynchronous request to the database.
The users variable, which is the actual SQLAlchemy table behind the table class.

What about SQLAlchemy ORM?¶

The primary objective was to use pure async approach as much as possible. However, we understand that ORM is convenient and useful for many developers. If this feature becomes very demanded, we will add a database adapter for SQLAlchemy ORM.