SQL

flask sqlalchemy single table inheritance

class User(db.Model):
    __tablename__ = 'tbl_user'
    type = db.Column(db.String(32)) 
    ...
    __mapper_args__ = {
        'polymorphic_identity': 'user',
        'polymorphic_on': type,
    }  # remove with_polymorphic

class Tourist(User):
    __tablename__ = None  # Add table name to be None
    __mapper_args__ = {
        'polymorphic_identity': 'tourist'
    }
    ...

class Guide(User):
    __tablename__ = None  # Add table name to be None
    __mapper_args__ = {
        'polymorphic_identity': 'guide'
    }
    ...

flask-sqlalchemy inheritance

import sqlalchemy as sa
from flask import Flask

from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_ECHO'] = True
db = SQLAlchemy(app)


class BaseModel(db.Model):
    __abstract__ = True
    id = sa.Column(sa.Integer, primary_key=True)


class A(BaseModel):
    a_name = sa.Column(sa.String)
    a_type = sa.Column(sa.String)
    __mapper_args__ = {
        'polymorphic_on': a_type,
        'polymorphic_identity': 'a',
    }


class B(BaseModel):
    b_name = sa.Column(sa.String)
    b_type = sa.Column(sa.String)
    __mapper_args__ = {
        'polymorphic_identity': 'b',
        'polymorphic_on': b_type
    }


class Inheritance(A, B):
    a_id = sa.Column(sa.ForeignKey(A.id), primary_key=True)
    b_id = sa.Column(sa.ForeignKey(B.id), primary_key=True)
    name = sa.Column(sa.String)


db.create_all()
db.session.add_all((A(), B()))
db.session.commit()
db.session.add(Inheritance(a_id=1, b_id=1))
db.session.commit()