[Flask] Establishing foreign key back to parent class
tim at akwebsoft.com
Sun Feb 14 18:24:19 EST 2016
* Tim Johnson <tim at akwebsoft.com> [160213 13:48]:
> # My working code is as follows:
> # class Base(db.Model):
> # __abstract_ = True
> # id = db.Column(db.Integer, primary_key=True)
> # date_created = db.Column(db.DateTime, default=db.func.current_timestamp())
> # date_modified = db.Column(db.DateTime, default=db.func.current_timestamp(),
> # onupdate=db.func.current_timestamp())
Turns out that I was bitten by a self-inflicted ORM bug... in my
original code as taken from the tutorial, I had truncated
__abstract__ to __abstract_ ## one trailing underscore!
Because __abstract__ was not defined as True sqlalchemy attempted
to map out a "base" table and subsequently create a relationship -
which failed and generated the exception.
The use of "special class directives" in sqlalchemy is discussed
live and learn ...
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