sqlalchemy-nest 1.1.1

easy create nested models for sqlalchemy

sqlalchemy-nest

sqlalchemy-nest is easy create nested models for sqlalchemy

Installation

pip install sqlalchemy-nest

Create Nested Model

1. Set declarative_base constructor

   use declarative_nested_model_constructor for declarative_base constructor

   from sqlalchemy import Column, ForeignKey, Integer, String
   from sqlalchemy.orm import declarative_base, relationship
   from sqlalchemy_nest import declarative_nested_model_constructor
   
   Base = declarative_base(constructor=declarative_nested_model_constructor)
   
   class Root(Base):
       __tablename__ = "root"
       
       id = Column(Integer, primary_key=True, autoincrement=True)
       name = Column(String(100))
       
       branches = relationship("Branch", back_populates="root", uselist=True, lazy="joined")
       
   class Branch(Base):
       __tablename__ = "branch"
       
       id = Column(Integer, primary_key=True, autoincrement=True)
       name = Column(String(100))
       root_id = Column(Integer, ForeignKey("root.id"))
       
       root = relationship("Root")
   

2. Initialization from **kwargs

   sets attributes on the constructed instance using the names and values in kwargs.

   root = {
       'name': 'root',
       'branches': [
           {
               'name': 'branch',
           },
       ] 
   }
   >>> session.add(Root(**root))
   >>> session.commit()
   >>> added_root: Root = session.query(Root).filter(Root.id == 1).first()
   Root(id=1, name='root', branches=[Branch(id=1, name='branch', root_id=1)])
   

Merge Nested Model

1. Set declarative_base constructor and cls

   use declarative_nested_model_constructor and BaseModel for declarative_base

   ⚠ sqlalchemy-nest checks viewonly to decide whether to update or not, so please set the viewonly property in the relationship. ⚠

   from sqlalchemy import Column, ForeignKey, Integer, String
   from sqlalchemy.orm import declarative_base, relationship
   from sqlalchemy_nest import declarative_nested_model_constructor
   from sqlalchemy_nest.orm import BaseModel
   
   Base = declarative_base(cls=BaseModel, constructor=declarative_nested_model_constructor)
   
   class Root(Base):
       __tablename__ = "root"
       
       id = Column(Integer, primary_key=True, autoincrement=True)
       name = Column(String(100))
       
       branches = relationship("Branch", back_populates="root", uselist=True, lazy="joined")
       
   class Branch(Base):
       __tablename__ = "branch"
       
       id = Column(Integer, primary_key=True, autoincrement=True)
       name = Column(String(100))
       root_id = Column(Integer, ForeignKey("root.id"))
       
       root = relationship("Root", viewonly=True)
   

2. Update from **kwargs

   root = {
       'name': 'root',
       'branches': [
           {
               'name': 'branch',
           },
       ] 
   }
   >>> session.add(Root(**root))
   >>> session.commit()
   >>> added_root: Root = session.query(Root).filter(Root.id == 1).first()
   Root(id=1, name='root', branches=[Branch(id=1, name='branch', root_id=1)])
   
   update_root = {
       'id': 1,
       'name': 'updated_root',
       'branches': [
           {
               'id': 1,
               'name': 'updated_branch',
           },
           {
               'name': 'created_branch',
           },
       ] 
   }
   >>> added_root.merge(**update_root)
   >>> session.commit()
   >>> updated_root: Root = session.query(Root).filter(Root.id == 1).first()
   Root(id=1, name='updated_root', branches=[Branch(id=1, name='updated_branch', root_id=1), Branch(id=2, name='created_branch', root_id=1)])