SQLAlchemy introspect column type with inheritance

Question

Considering this code (and using SQLAlchemy 0.7.7):

class Document(Base):
    __tablename__ = \'document\'
    __table_args__ = {
        \'schema\': \'app\'
            


        

Answer 1

You need the abstract special directive or the mixin pattern.

For a mixin, you'd use something like this:

class MyMixin(object):
    __tablename__ = 'document'
    __table_args__ = {
        'schema': 'app'
    }

    id = Column(types.Integer, primary_key=True)
    nom = Column(types.Unicode(256), nullable=False)
    date = Column(types.Date())

class Arrete(MyMixin, Base):
    __tablename__ = 'arrete'

    __mapper_args__ = {'polymorphic_identity': 'arrete'}

    foreign_id = Column(types.Integer, ForeignKey('app.document.id'), primary_key=True)
    numero_arrete = Column(types.Integer)
    date_arrete = Column(types.Date())


class Document(MyMixin, Base):
    __tablename__ = 'Document'
    type_document = Column(types.Enum('arrete', 'photographie',
        name='TYPES_DOCUMENT_ENUM'))
    __mapper_args__ = {'polymorphic_on': type_document}

Shared stuff goes in the mixin, non shared stuff in the sub classes.