FlaskにMIXINはどのように実装できますか？

Question

ベースクラスを使用するのではなく、Mixinを使用したい、私はFLASKでMixinsを使用することに関する多くの文書を見つけられませんでした。私はこの抽象的な基本クラスの代わりにミックスインをどのように実装することができますか？ミックスインとSQLAlchemyの上

class Base(db.Model): 
    """ 
    Base class for models. 

    Define the base class for the models so others can inherit from it. 
    """ 

    __abstract__ = True 

    def save(self): 
     """ 
     Save to database. 

     Save instance of the object to database and commit. 
     """ 
     db.session.add(self) 
     db.session.commit() 

    def delete(self): 
     """ 
     Delete from database. 

     Deletes instance of an object from database 
     """ 
     db.session.delete(self) 
     db.session.commit() 


class User(Base): 
    """ 
    Set up the User model. 

    Set up the properties of the User object and the table name too. 
    """ 

    __tablename__ = 'users' 
    user_id = db.Column(db.Integer, primary_key=True) 
    username = db.Column(db.String(32), unique=True, index=True, 
         nullable=False) 
    password_hash = db.Column(db.String(128), nullable=False) 
    date_created = db.Column(
     db.DateTime, default=datetime.now(), nullable=False) 
    date_modified = db.Column(
     db.DateTime, default=datetime.now(), 
     onupdate=datetime.now(), nullable=False) 

    def hash_password(self, password): 
     """ 
     Hash user password. 

     Passwords shouldn't be stored as string so we hash them. 
     """ 
     self.password_hash = generate_password_hash(password) 

Answer 1

ドキュメントはここにある：あなたの具体的な例http://docs.sqlalchemy.org/en/latest/orm/extensions/declarative/mixins.html

、ここにあなたのためにいくつかのコードは、次にあなたがそのミックスインを使用することができますhttps://github.com/mjhea0/flask-tracking

from app import db 

class CRUDMixin(object): 
    __table_args__ = {'extend_existing': True} 

    id = Column(db.Integer, primary_key=True) 

    @classmethod 
    def get_by_id(cls, id): 
     if any(
      (isinstance(id, str) and id.isdigit(), 
      isinstance(id, (int, float))), 
     ): 
      return cls.query.get(int(id)) 
     return None 

    @classmethod 
    def create(cls, **kwargs): 
     instance = cls(**kwargs) 
     return instance.save() 

    def update(self, commit=True, **kwargs): 
     for attr, value in kwargs.iteritems(): 
      setattr(self, attr, value) 
     return commit and self.save() or self 

    def save(self, commit=True): 
     db.session.add(self) 
     if commit: 
      db.session.commit() 
     return self 

    def delete(self, commit=True): 
     db.session.delete(self) 
     return commit and db.session.commit() 

に基づき、次のとおりです。

from app import db 
from mymixins import CRUDMixin 

class User(CRUDMixin, db.Model): 

    """ 
    Set up the User model. 

    Set up the properties of the User object and the table name too. 
    """ 

    __tablename__ = 'users' 
    username = db.Column(db.String(32), unique=True, index=True, 
         nullable=False) 
    password_hash = db.Column(db.String(128), nullable=False) 
    date_created = db.Column(
     db.DateTime, default=datetime.now(), nullable=False) 
    date_modified = db.Column(
     db.DateTime, default=datetime.now(), 
     onupdate=datetime.now(), nullable=False) 

    def hash_password(self, password): 
     """ 
     Hash user password. 

     Passwords shouldn't be stored as string so we hash them. 
     """ 
     self.password_hash = generate_password_hash(password)