Python SQLAlchemy
SQLAlchemy is the Python SQL toolkit and Object Relational Mapper (ORM) that gives application developers the full power and flexibility of SQL.
Installation
pip install SQLAlchemyConnecting to a Database
To connect to a database, we use create_engine():
from sqlalchemy import create_engine
# SQLite database
engine = create_engine('sqlite:///example.db', echo=True)Declarative Mapping
SQLAlchemy uses a system known as Declarative to define classes that map to database tables.
from sqlalchemy.orm import declarative_base
from sqlalchemy import Column, Integer, String
Base = declarative_base()
class User(Base):
__tablename__ = 'users'
id = Column(Integer, primary_key=True)
name = Column(String)
fullname = Column(String)
nickname = Column(String)
def __repr__(self):
return f"<User(name='{self.name}', fullname='{self.fullname}', nickname='{self.nickname}')>"Creating the Schema
Base.metadata.create_all(engine)Creating a Session
The Session is the handle to the database.
from sqlalchemy.orm import sessionmaker
Session = sessionmaker(bind=engine)
session = Session()CRUD Operations
Create
ed_user = User(name='ed', fullname='Ed Jones', nickname='edsnickname')
session.add(ed_user)
session.commit()Read
our_user = session.query(User).filter_by(name='ed').first()
print(our_user)Update
ed_user.nickname = 'eddie'
session.commit()Delete
session.delete(ed_user)
session.commit()