Can't validate argument 'bind_key'

[one-more-alex]

After connecting active-sqlalchemy I got strange warnings:

/usr/local/lib/python2.7/dist-packages/sqlalchemy/sql/schema.py:552: SAWarning: Can't validate argument 'bind_key'; can't locate any SQLAlchemy dialect named 'bind'
self._validate_dialect_kwargs(kwargs)

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  /usr/local/lib/python2.7/dist-packages/sqlalchemy/sql/schema.py:552: SAWarning: Can't validate argument 'bind_key'; can't locate any SQLAlchemy dialect named 'bind'
  self._validate_dialect_kwargs(kwargs)

[lexicalunit]

I am also having this issue.

from active_alchemy import SQLAlchemy
from flask import Flask

app = Flask(__name__)
db = SQLAlchemy('mysql+mysqldb://admin:admin@192.168.99.100:3306/my_database', app=app)

event_participants = db.Table(
    'event_participants', db.metadata,
    db.Column('event_id', db.Integer, db.ForeignKey('events.id')),
    db.Column('person_id', db.Integer, db.ForeignKey('persons.id')))


class Event(db.Model):
    __tablename__ = 'events'
    id = db.Column(db.Integer, primary_key=True)
    participants = db.relationship('Person',
                                   secondary='event_participants',
                                   backref='participating')


class Person(db.Model):
    __tablename__ = 'persons'
    id = db.Column(db.Integer, primary_key=True)

if __name__ == '__main__':
    app.run()

When I run this tiny representative example code I get the following warning:

$ python example.py
/path/to/my/site-packages/sqlalchemy/sql/base.py:291: SAWarning: Can't validate argument 'bind_key'; can't locate any SQLAlchemy dialect named 'bind'
  (k, dialect_name))
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In this example I am setting up a many-to-many relationship between events and persons. Meaning 1) there can be many events a person is participating in and 2) many persons can be attending an event. Documentation for setting up this kind of relationship with SQLAlchemy can be found here: http://docs.sqlalchemy.org/en/latest/orm/basic_relationships.html#many-to-many which is what the structure for my example code is based on.