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utility for portable model definition of sqlalchemy models

Project description

  • utility for portable model definition with sqlalchemy
  • black magic? of cource.

what is portable model definition?

sqlalchemy, it is ok that just definition declarative model class depends on another model. (e.g. We have two model, Group and User. User depends on Group Model.)

But,when providing model classes like these as a library, we are thinking about portability.

  • Library User: creating Operator model depends on User. but User class is provided by Library.
  • Library Author: We have convinient User Model, so, share it.
  • (Both of Two): but’s what tablename is this Model?(e.g. User,user,users,mylib_users?)

This package’s motibation is solving such a problem like above.

How to use this?

Library Author code:

#foo/auth.py
import sqlalchemy as sa
from sqlalchemy.orm import relationship
from sqlaqb import (
    ModelCreation,
    ModuleProvider,
    ModelSeed,
    with_tablename,
    with_modelname,
)

creation = ModelCreation()
_provider = ModuleProvider(creation)
create_models = _provider

@creation.register("Group")
class Group(ModelSeed):
    id=sa.Column(sa.Integer, primary_key=True, nullable=False)
    name=sa.Column(sa.String(255), nullable=False)

@creation.register("User", depends=["Group"])
class User(ModelSeed):
    id=sa.Column(sa.Integer, primary_key=True, nullable=False)
    name=sa.Column(sa.String(255), nullable=False)

    @with_tablename("Group")
    def group_id(cls, group_table_name):
        return sa.Column(sa.Integer, sa.ForeignKey("{}.id".format(group_table_name)), nullable=True)

    @with_modelname("Group")
    def group(cls, name):
        return relationship(name)

    def verify_password(self, password):
        return self.password_digest == password

Library User can decide table name provided by library.

Library User code:

from foo.auth import create_models
from sqlalchemy.ext.declarative import declarative_base

Base = declarative_base()
contract = {"User": {"table_name": "users"},
            "Group": {"table_name": "groups", "model_name": "_Group"}}
models = create_models(Base, contract)

models._Group # Group model defined in foo.auth.py
models.User # User model defined in foo.auth.py

more over, also enable to inject dependents model.

Library User code:

from foo.auth import create_models
from sqlalchemy.ext.declarative import declarative_base

Base = declarative_base()
class MyGroup(Base):
    id = sa.Column(sa.Integer, primary_key=True, nullable=False)
    special = sa.Column(sa.String("32"), doc="this is special")
    __tablename__ = "my_groups"

contract = {"User": {"table_name": "users"},
            "Group": {"model": MyGroup}}

models = create_models(Base, contract)

models.Group # Group model define by library user
models.User # User model defined in foo.auth.py

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