SQL的炼金术; 外键错误

Question

My problem comes down to the following code:

class TaskOneLine(db.Model):
    userId = db.Column(db.String(64), primary_key=True)
    timestampStart = db.Column(db.BIGINT, primary_key=True, autoincrement=False)
    includedObjects = db.relationship("TaskOneIncludedObject")

class TaskOneIncludedObject(db.Model):
    id = db.Column(db.BIGINT, primary_key=True)

    #parent foreign key required for one-to-many-relation
    userId = db.Column(db.String(64), db.ForeignKey('task_one_line.userId'))
    timestampStart = db.Column(db.BIGINT, db.ForeignKey('task_one_line.timestampStart'), autoincrement=False)

(It's the wrapped sql-alchemy from flask but I'm pretty sure this does not matter for this problem.)

The above gives me:

sqlalchemy.exc.OperationalError: (OperationalError) (1005, "Can't create table 'crowdtracker.task_one_included_object' (errno: 150)")

I can not undertand why I'm getting this error. When I remove the timestampStart Column the queries run through. I also added autoincrement=False to the foreign key without success.

Best regards

Answer 1

I solved it now by defining the composite foreign key via ForeignKeyConstraint() which seems to support composite foreign keys. ( http://docs.sqlalchemy.org/en/rel_0_9/core/constraints.html#defining-foreign-keys )