SQLAlchemy (1.0.8)
On Friday, September 15, 2017 at 12:14:33 PM UTC-4, Conferency wrote:
>
> class Paper(db.Model):
> __tablename__ = 'papers'
> reviewers = db.relationship('User', secondary=paper_reviewer,
> backref=db.backref('papers_reviewed',
> lazy='dynamic'),
> lazy='dynamic')
>
> paper_reviewer = db.Table('paper_reviewer',
> db.Column('user_id', db.Integer,
> db.ForeignKey('users.id'),
> primary_key=True),
> db.Column('paper_id', db.Integer,
> db.ForeignKey('papers.id'),
> primary_key=True)
> )
> @event.listens_for(Paper.reviewers, 'append')def
> paper_reviewers_append(target, value, initiator):
> # select queries...
>
>
>
> paper.reviewers.append(usr)
> db.session.add(paper)
> db.session.commit()
>
> The listener is fired before the execution of paper.reviewers.append(usr).
> The execution of append makes two insertions into paper_reviewer table. The
> second one causes IntegrityError: UNIQUE constraint failed.
>
> I tried different operations in the listener. If the operation in listener
> triggered any query, the IntegrityError would be caused while the commit()
> was executed. Not sure why listener could cause this error. Can anyone give
> me some details? Plz
>
>
--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
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