`compare_server_default` parses `(getdate())` incorrectly

[GeorgeSchneelochVA]

Describe the bug
In our MS SQL Server database we have a default constraint which is (getdate()) for a column. For some reason flask db migrate was detecting a change even though our server_default value in our SQLAlchemy model was also (getdate()). I inspected it with pdb.set_trace() and found that compare_server_default is converting (getdate()) to getdate(.

It looks like this commit introduced the bug. In particular, there are slightly different regular expressions being used to clean inspector_column and metadata_column, which is why the comparison for this particular string was false.

Expected behavior
compare_server_default should clean the expression appropriately for both the metadata and inspector defaults, and compare
the cleaned values with each other.

To Reproduce

• Create a model with one datetime column with server_default=(getdate())
• Create a corresponding table with the same column and the same default constraint
• Run flask db migrate. You should not see any difference in schema, but since the comparison fails there will be a migration script created.

Versions.

• OS: Windows Server 2019
• Python: 3.8
• Alembic: 1.9.1
• SQLAlchemy: 1.4.39
• Database: SQL Server 2019
• DBAPI:

[CaselIT]

Hi,

Thanks for reporting.

[sqla-tester]

Mike Bayer has proposed a fix for this issue in the main branch:

repair regression in SQL Server server default comapre logic https://gerrit.sqlalchemy.org/c/sqlalchemy/alembic/+/4352

[GeorgeSchneelochVA]

Thanks for the fix!