Cookbook recipe for re-ordering columns isn't working?

[ghost]

Out of an abundance of curiosity (and unbelievably fussy pickiness), I'm trying out the recipe here to order my columns in autogenerated tables. I've copied the code verbatim into my env.py, and added logging, so I can see that each call to the rewriter.Rewriter() function is happening; but then, when Alembic goes to write the actual migration, I get the following traceback:

Traceback (most recent call last):
  File "/Users/jfb/Work/monohelix/projects/role_explorer/.venv/bin/alembic", line 8, in <module>
    sys.exit(main())
             ^^^^^^
  File "/Users/jfb/Work/monohelix/projects/role_explorer/.venv/lib/python3.11/site-packages/alembic/config.py", line 591, in main
    CommandLine(prog=prog).main(argv=argv)
  File "/Users/jfb/Work/monohelix/projects/role_explorer/.venv/lib/python3.11/site-packages/alembic/config.py", line 585, in main
    self.run_cmd(cfg, options)
  File "/Users/jfb/Work/monohelix/projects/role_explorer/.venv/lib/python3.11/site-packages/alembic/config.py", line 562, in run_cmd
    fn(
  File "/Users/jfb/Work/monohelix/projects/role_explorer/.venv/lib/python3.11/site-packages/alembic/command.py", line 236, in revision
    scripts = [script for script in revision_context.generate_scripts()]
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/jfb/Work/monohelix/projects/role_explorer/.venv/lib/python3.11/site-packages/alembic/command.py", line 236, in <listcomp>
    scripts = [script for script in revision_context.generate_scripts()]
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/jfb/Work/monohelix/projects/role_explorer/.venv/lib/python3.11/site-packages/alembic/autogenerate/api.py", line 605, in generate_scripts
    yield self._to_script(generated_revision)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/jfb/Work/monohelix/projects/role_explorer/.venv/lib/python3.11/site-packages/alembic/autogenerate/api.py", line 505, in _to_script
    render._render_python_into_templatevars(
  File "/Users/jfb/Work/monohelix/projects/role_explorer/.venv/lib/python3.11/site-packages/alembic/autogenerate/render.py", line 83, in _render_python_into_templatevars
    _render_cmd_body(upgrade_ops, autogen_context)
  File "/Users/jfb/Work/monohelix/projects/role_explorer/.venv/lib/python3.11/site-packages/alembic/autogenerate/render.py", line 108, in _render_cmd_body
    lines = render_op(autogen_context, op)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/jfb/Work/monohelix/projects/role_explorer/.venv/lib/python3.11/site-packages/alembic/autogenerate/render.py", line 126, in render_op
    lines = util.to_list(renderer(autogen_context, op))
                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/jfb/Work/monohelix/projects/role_explorer/.venv/lib/python3.11/site-packages/alembic/autogenerate/render.py", line 226, in _add_table
    for rcons in [
                 ^
  File "/Users/jfb/Work/monohelix/projects/role_explorer/.venv/lib/python3.11/site-packages/alembic/autogenerate/render.py", line 227, in <listcomp>
    _render_constraint(
  File "/Users/jfb/Work/monohelix/projects/role_explorer/.venv/lib/python3.11/site-packages/alembic/autogenerate/render.py", line 916, in _render_constraint
    return renderer(constraint, autogen_context, namespace_metadata)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/jfb/Work/monohelix/projects/role_explorer/.venv/lib/python3.11/site-packages/alembic/autogenerate/render.py", line 1017, in _render_foreign_key
    apply_metadata_schema = namespace_metadata.schema
                            ^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'schema'

This is alembic v1.10, Python 3.11.

I do have three schemas in play, each with ~5-10 tables in them. There are cross schema constraints and such, but what's odd to me is that taking the process_revision_directives argument out of my context.configure() means the revision is happily generated. I'm a bit puzzled. I can post more of the code, but I'm wondering if there's something obvious I'm missing, here?

TIA for any pointers, advice, brickbats. Cheers!

[zzzeek]

it's likely the recipe broke either due to an alembic or a SQLAlchemy release. if you have time, maybe try SQLAlchemy 1.4 and/or an older version of Alembic. Otherwise someone here will run the recipe and see where it broke...

[ghost]

Well, some hapless fumbling, and it looks like there's a bunch of stuff hanging on the CreateTableOp that wasn't getting copied to the new CreateTableOp statement with the re-ordered columns. I added a very ugly bit and now it seems to be ... ok?

    return ops.CreateTableOp(
        op.table_name,
        columns=columns,
        schema=op.schema,
        info=op.info,
        comment=op.comment,
        prefixes=op.prefixes,
        _namespace_metadata=op._namespace_metadata,
        _constraints_included=op._constraints_included,
        **op.kw
    )

Now, to tilt at the next windmill -- adding a trigger automatically for tables with certain predicates. Wheee!

[zzzeek]

that's a bug on our end. will add

[ghost]

👍 cheers on the quick turnaround!

[zzzeek]

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