flask 使用 SQLAlchemy 的两种方式

1. 使用 flask-SQLAlchemy 扩展

# flask-ext-sqlalchemy.py

from flask import Flask
from flask.ext.sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite://'
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = True
db = SQLAlchemy(app)

# 定义ORM
class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(80), unique=True)
    email = db.Column(db.String(120), unique=True)

    def __init__(self, name, email):
        self.name = name
        self.email = email

    def __repr__(self):
        return '<User %r>' % self.name

# 创建表格、插入数据
@app.before_first_request
def setup():
    # Recreate database each time for demo
    db.create_all()

    admin = User('admin', 'admin@example.com')
    db.session.add(admin)

    guestes = [User('guest1', 'guest1@example.com'),
               User('guest2', 'guest2@example.com'),
               User('guest3', 'guest3@example.com'),
               User('guest4', 'guest4@example.com')]
    db.session.add_all(guestes)
    db.session.commit()

# 查询
@app.route('/user')
def users():
    users = User.query.all()
    return "<br>".join(["{0}: {1}".format(user.name, user.email) for user in users])

# 查询
@app.route('/user/<int:id>')
def user(id):
    user = User.query.filter_by(id=id).one()
    return "{0}: {1}".format(user.name, user.email)

# 运行
if __name__ == '__main__':
    app.run('127.0.0.1', 5000) 

2. 使用原生 SQLAlchemy

# flask-pure-sqlalchemy.py

from flask import Flask
from sqlalchemy import Column, Integer, String
from sqlalchemy import create_engine
from sqlalchemy.orm import Session
from sqlalchemy.ext.declarative import declarative_base

app =  Flask(__name__)

Base = declarative_base()
# 定义ORM
class User(Base):
    __tablename__ = 'users'

    id = Column(Integer, primary_key=True)
    name = Column(String(50), unique=True)
    email = Column(String(120), unique=True)

    def __init__(self, name=None, email=None):
        self.name = name
        self.email = email

    def __repr__(self):
        return '<User %r>' % (self.name)

# 创建表格、插入数据
@app.before_first_request
def setup():
    # Recreate database each time for demo
    engine = create_engine('sqlite://', echo=True)
    global session
    session = Session(engine)

    Base.metadata.drop_all(bind=engine)
    Base.metadata.create_all(bind=engine)

    admin = User('admin', 'admin@example.com')
    session.add(admin)

    guestes = [User('guest1', 'guest1@example.com'),
               User('guest2', 'guest2@example.com'),
               User('guest3', 'guest3@example.com'),
               User('guest4', 'guest4@example.com')]
    session.add_all(guestes)
    session.commit()

# 查询
@app.route('/user')
def users():
    users = session.query(User).all()
    return "<br>".join(["{0}: {1}".format(user.name, user.email) for user in users])

@app.route('/user/<int:id>')
def user(id):
    user = session.query(User).filter(User.id == id).one()
    return "{0}: {1}".format(user.name, user.email)

if __name__ == '__main__':
    app.run('127.0.0.1', 5000) 

区别