Modify flask configuration with naming convention

[maham360]

I added this naming convention in my models.py file:

db = SQLAlchemy(metadata=MetaData(naming_convention={
    'pk': 'pk_%(table_name)s',
    'fk': 'fk_%(table_name)s_%(column_0_name)s_%(referred_table_name)s',
    'ix': 'ix_%(table_name)s_%(column_0_name)s',
    'uq': 'uq_%(table_name)s_%(column_0_name)s',
    'ck': 'ck_%(table_name)s_%(constraint_name)s',
}))
Base = declarative_base(metadata=db)

And when I run flask db migrate I get the error:

sqlalchemy.exc.InvalidRequestError: When initializing mapper mapped class User->users, expression 'user_to_service' failed to locate a name ("name 'user_to_service' is not defined"). If this is a class name, consider adding this relationship() to the <class 'app.model.user.User'> class after both dependent classes have been defined.

Here is the traceback for that error:

Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/ext/declarative/clsregistry.py", line 326, in __call__
    x = eval(self.arg, globals(), self._dict)
  File "<string>", line 1, in <module>
NameError: name 'user_to_service' is not defined

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/usr/local/bin/flask", line 8, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.8/site-packages/flask/cli.py", line 966, in main
    cli.main(prog_name="python -m flask" if as_module else None)
  File "/usr/local/lib/python3.8/site-packages/flask/cli.py", line 586, in main
    return super(FlaskGroup, self).main(*args, **kwargs)
  File "/usr/local/lib/python3.8/site-packages/click/core.py", line 1053, in main
    rv = self.invoke(ctx)
  File "/usr/local/lib/python3.8/site-packages/click/core.py", line 1659, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/local/lib/python3.8/site-packages/click/core.py", line 1659, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/local/lib/python3.8/site-packages/click/core.py", line 1395, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/local/lib/python3.8/site-packages/click/core.py", line 754, in invoke
    return __callback(*args, **kwargs)
  File "/usr/local/lib/python3.8/site-packages/click/decorators.py", line 26, in new_func
    return f(get_current_context(), *args, **kwargs)
  File "/usr/local/lib/python3.8/site-packages/flask/cli.py", line 425, in decorator
    with __ctx.ensure_object(ScriptInfo).load_app().app_context():
  File "/usr/local/lib/python3.8/site-packages/flask/cli.py", line 388, in load_app
    app = locate_app(self, import_name, name)
  File "/usr/local/lib/python3.8/site-packages/flask/cli.py", line 240, in locate_app
    __import__(module_name)
  File "/app/application.py", line 11, in <module>
    from app import create_app
  File "/app/app/__init__.py", line 52, in <module>
    from app.clients.email.govdelivery_client import GovdeliveryClient  # noqa
  File "/app/app/clients/email/govdelivery_client.py", line 1, in <module>
    from app.models import (NOTIFICATION_CANCELLED, NOTIFICATION_DELIVERED, NOTIFICATION_PERMANENT_FAILURE,
  File "/app/app/models.py", line 368, in <module>
    class Service(db.Model, Versioned):
  File "/usr/local/lib/python3.8/site-packages/flask_sqlalchemy/model.py", line 67, in __init__
    super(NameMetaMixin, cls).__init__(name, bases, d)
  File "/usr/local/lib/python3.8/site-packages/flask_sqlalchemy/model.py", line 121, in __init__
    super(BindMetaMixin, cls).__init__(name, bases, d)
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/ext/declarative/api.py", line 76, in __init__
    _as_declarative(cls, classname, cls.__dict__)
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/ext/declarative/base.py", line 131, in _as_declarative
    _MapperConfig.setup_mapping(cls, classname, dict_)
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/ext/declarative/base.py", line 160, in setup_mapping
    cfg_cls(cls_, classname, dict_)
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/ext/declarative/base.py", line 194, in __init__
    self._early_mapping()
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/ext/declarative/base.py", line 199, in _early_mapping
    self.map()
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/ext/declarative/base.py", line 695, in map
    self.cls.__mapper__ = mp_ = mapper_cls(
  File "/app/app/history_meta.py", line 164, in map
    _history_mapper(mp)
  File "/app/app/history_meta.py", line 42, in _history_mapper
    for prop in local_mapper.iterate_properties:
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/mapper.py", line 2081, in iterate_properties
    configure_mappers()
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/mapper.py", line 3301, in configure_mappers
    mapper._post_configure_properties()
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/mapper.py", line 1966, in _post_configure_properties
    prop.init()
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/interfaces.py", line 197, in init
    self.do_init()
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/relationships.py", line 2076, in do_init
    self._process_dependent_arguments()
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/relationships.py", line 2105, in _process_dependent_arguments
    setattr(self, attr, attr_value())
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/ext/declarative/clsregistry.py", line 333, in __call__
    self._raise_for_name(n.args[0], n)
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/ext/declarative/clsregistry.py", line 293, in _raise_for_name
    util.raise_(
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/util/compat.py", line 182, in raise_
    raise exception

I'm not sure where to add the naming convention based off this. Is this a flask configuration issue?

[davidism]

This is not a Flask or Flask-SQLAlchemy issue, it appears to be an issue with how you've defined some of your models and relationships.

[maham360]

Ok, here is the source table:

class Complaint(db.Model):
    __tablename__ = 'complaints'

    id = db.Column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
    notification_id = db.Column(UUID(as_uuid=True), db.ForeignKey('notification_history.id'),
                                index=True, nullable=False)
    service_id = db.Column(UUID(as_uuid=True), db.ForeignKey('services.id'), unique=False, index=True, nullable=False)
    service = db.relationship(Service, backref=db.backref('complaints'))
    feedback_id = db.Column(db.Text, nullable=True)
    complaint_type = db.Column(db.Text, nullable=True, default=UNKNOWN_COMPLAINT_TYPE)
    complaint_date = db.Column(db.DateTime, nullable=True)
    created_at = db.Column(db.DateTime, nullable=False, default=datetime.datetime.utcnow)

    def serialize(self):
        return {
            'id': str(self.id),
            'notification_id': str(self.notification_id),
            'service_id': str(self.service_id),
            'service_name': self.service.name,
            'feedback_id': str(self.feedback_id),
            'complaint_type': self.complaint_type,
            'complaint_date': self.complaint_date.strftime(DATETIME_FORMAT) if self.complaint_date else None,
            'created_at': self.created_at.strftime(DATETIME_FORMAT),
        }

And here is the reference table:

class NotificationHistory(db.Model, HistoryModel):
    __tablename__ = 'notification_history'

    id = db.Column(UUID(as_uuid=True), primary_key=True)
    job_id = db.Column(UUID(as_uuid=True), db.ForeignKey('jobs.id'), index=True, unique=False)
    job = db.relationship('Job')
    job_row_number = db.Column(db.Integer, nullable=True)
    service_id = db.Column(UUID(as_uuid=True), db.ForeignKey('services.id'), index=True, unique=False)
    service = db.relationship('Service')
    template_id = db.Column(UUID(as_uuid=True), index=True, unique=False)
    template_version = db.Column(db.Integer, nullable=False)
    api_key_id = db.Column(UUID(as_uuid=True), db.ForeignKey('api_keys.id'), index=True, unique=False)
    api_key = db.relationship('ApiKey')
    key_type = db.Column(db.String, db.ForeignKey('key_types.name'), index=True, unique=False, nullable=False)
    billable_units = db.Column(db.Integer, nullable=False, default=0)
    notification_type = db.Column(notification_types, index=True, nullable=False)
    created_at = db.Column(db.DateTime, index=True, unique=False, nullable=False)
    sent_at = db.Column(db.DateTime, index=False, unique=False, nullable=True)
    sent_by = db.Column(db.String, nullable=True)
    updated_at = db.Column(db.DateTime, index=False, unique=False, nullable=True, onupdate=datetime.datetime.utcnow)
    status = db.Column(
        'notification_status',
        db.Text,
        db.ForeignKey('notification_status_types.name'),
        index=True,
        nullable=True,
        default='created',
        key='status'  # http://docs.sqlalchemy.org/en/latest/core/metadata.html#sqlalchemy.schema.Column
    )
    reference = db.Column(db.String, nullable=True, index=True)
    client_reference = db.Column(db.String, nullable=True)

    international = db.Column(db.Boolean, nullable=True, default=False)
    phone_prefix = db.Column(db.String, nullable=True)
    rate_multiplier = db.Column(db.Numeric(asdecimal=False), nullable=True)

    created_by_id = db.Column(UUID(as_uuid=True), nullable=True)

    postage = db.Column(db.String, nullable=True)
    status_reason = db.Column(db.String, nullable=True)
    billing_code = db.Column(db.String(256), nullable=True)
    CheckConstraint("""
        CASE WHEN notification_type = 'letter' THEN
            postage is not null and postage in ('first', 'second')
        ELSE
            postage is null
        END
    """)

    __table_args__ = (
        db.ForeignKeyConstraint(
            ['template_id', 'template_version'],
            ['templates_history.id', 'templates_history.version'],
        ),
        {}
    )

When I produce a new migration I am getting an error stating:
op.create_foreign_key(None, 'complaints', 'notification_history', ['notification_id'], ['id']) meaning there is no foreign key constraint name on complaints.notification_id so it's showing up as 'None'. I'm not sure if I had to define the foreign key constraint in db.ForeignKeyConstraint?