5.Marshmallow-SQLAlchemy轻量级序列化和反序列化包

Marshmallow，中文译作：棉花糖。是一个轻量级的数据格式转换的模块，也叫序列化和反序列化模块，常用于将复杂的orm模型对象与python原生数据类型之间相互转换。marshmallow提供了丰富的api功能

基本使用

import sqlalchemy as sa
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import scoped_session, sessionmaker, relationship, backref

engine = sa.create_engine("sqlite:///:memory:")
session = scoped_session(sessionmaker(bind=engine))
Base = declarative_base()


class Author(Base):
    __tablename__ = "authors"
    id = sa.Column(sa.Integer, primary_key=True)
    name = sa.Column(sa.String, nullable=False)

    def __repr__(self):
        return "".format(self=self)


class Book(Base):
    __tablename__ = "books"
    id = sa.Column(sa.Integer, primary_key=True)
    title = sa.Column(sa.String)
    author_id = sa.Column(sa.Integer, sa.ForeignKey("authors.id"))
    author = relationship("Author", backref=backref("books"))


Base.metadata.create_all(engine)

from marshmallow_sqlalchemy import SQLAlchemyAutoSchema


class AuthorSchema(SQLAlchemyAutoSchema):
    class Meta:
        model = Author
        include_relationships = True
        load_instance = True


class BookSchema(SQLAlchemyAutoSchema):
    class Meta:
        model = Book
        include_fk = True
        load_instance = True

author = Author(name="Chuck Paluhniuk")
author_schema = AuthorSchema()
book = Book(title="Fight Club", author=author)
session.add(author)
session.add(book)
session.commit()

dump_data = author_schema.dump(author)
print(dump_data)
# {'id': 1, 'name': 'Chuck Paluhniuk', 'books': [1]}

load_data = author_schema.load(dump_data, session=session)
print(load_data)
# 

2.模型构造器(ModelSchema)

class UserSchema(SQLAlchemyAutoSchema):
    class Meta:
        model = 模型类名    # table = models.Album.__table__
        include_relationships = True  # 输出模型对象时同时对外键，是否也一并进行处理
        include_fk = True # 序序列阶段是否也一并返回主键
        load_instance = True  # 反序列化阶段时，直接返回模型对象
        sql_session = db.session # 数据库连接会话对象
        # fields= ["id","name"] # 启动的字段列表
        exclude = ["id","name"] # 排除字段列表

注意：flask_marshmallow在0.12.0版本以后已经移除了ModelSchema和TableSchema这两个模型构造器类，官方转而推荐了使用SQLAlchemyAutoSchema和SQLAlchemySchema这2个类，前后两者用法类似