Problem with foreign keys

[jschultz]

I have stumbled on a bug that appears to be in sqlalchemy-sqlany, as it only appears to occur with SQL Anywhere databases. I reported the problem on the sqlalchemy Google group here.

In brief, doing reflection on certain tables, I receive the exception:

sqlalchemy.exc.ArgumentError: ForeignKeyConstraint with duplicate source column references are not supported.

The table in question does have foreign keys, but none with duplicate source columns:

ALTER TABLE test.wiwalisataob2aaf.Annotation
ADD FOREIGN KEY (Item_Id)
REFERENCES Item (Id);

ALTER TABLE test.wiwalisataob2aaf.Annotation
ADD FOREIGN KEY (CreatedBy,ModifiedBy)
REFERENCES UserProfile (Id,Id);

ALTER TABLE test.wiwalisataob2aaf.Annotation
ADD FOREIGN KEY (CompoundSourceRegion_Id,Item_Id)
REFERENCES CompoundSourceRegion (Id,Item_Id);

The problem seems to concern the way that foreign key constraints are detected or handled, but that's about all I know so far. I'll have a go debugging the problem myself, but any assistance or pointers would be most welcome.

[jschultz]

The problem is provoked when there are multiple foreign keys from the same table within a single table. The archetypal example is CreatedBy and ModifiedBy fields that both contain foreign keys in a User table. I resolved the problem in pull request #10