Columns and tables comments with MSSQL

[edulauer]

Describe the bug
When using the operations.alter_column to include a comment in a column of a MSSQL table it gets an error. Is it possible with alembic to generate columns and table descriptions with MSSQL using operations or Batchoperations?

Expected behavior
It's expected to update the table in the database and the columns description.

To Reproduce

conn = engine.connect()
ctx = MigrationContext.configure(conn)
op = Operations(ctx)

**op.alter_column**("table_name", "column_name", schema="schema_name", comment="Test Comment")

Error

AttributeError                            Traceback (most recent call last)
/usr/local/lib/python3.7/site-packages/sqlalchemy/sql/visitors.py in _compiler_dispatch(self, visitor, **kw)
     76         try:
---> 77             meth = getter(visitor)
     78         except AttributeError as err:

AttributeError: 'MSDDLCompiler' object has no attribute 'visit_clause'

The above exception was the direct cause of the following exception:

UnsupportedCompilationError               Traceback (most recent call last)
/usr/local/lib/python3.7/site-packages/sqlalchemy/ext/compiler.py in _wrap_existing_dispatch(element, compiler, **kw)
    529                     try:
--> 530                         return existing_dispatch(element, compiler, **kw)
    531                     except exc.UnsupportedCompilationError as uce:

/usr/local/lib/python3.7/site-packages/sqlalchemy/sql/visitors.py in _compiler_dispatch(self, visitor, **kw)
     78         except AttributeError as err:
---> 79             return visitor.visit_unsupported_compilation(self, err, **kw)
     80 

/usr/local/lib/python3.7/site-packages/sqlalchemy/sql/compiler.py in visit_unsupported_compilation(self, element, err)
    483             exc.UnsupportedCompilationError(self, type(element)),
--> 484             replace_context=err,
    485         )

/usr/local/lib/python3.7/site-packages/sqlalchemy/util/compat.py in raise_(***failed resolving arguments***)
    207         try:
--> 208             raise exception
    209         finally:

UnsupportedCompilationError: Compiler <sqlalchemy.dialects.mssql.base.MSDDLCompiler object at 0x7f13e0ec57d0> can't render element of type <class 'alembic.ddl.base.ColumnComment'> (Background on this error at: https://sqlalche.me/e/14/l7de)

Versions.

• OS: Linux
• Python: 3.9.5
• Alembic: 1.7.6
• SQLAlchemy: 1.4.43
• Database: Microsoft SQL Server 2016

Additional context
Is it possible with alembic to generate columns and table descriptions with MSSQL using operations or Batchoperations?

Have a nice day!

[CaselIT]

Hi,

This feature was implemented in sqlalchemy v2 that is currently in beta. https://docs.sqlalchemy.org/en/20/changelog/changelog_20.html#change-5381b6da8f1e1e87292d63c7a815282c

converting to discussion, since it's fixed

[edulauer]

Thanks!! I'll take a look using sqlalchemy v2.