Thanks for pointing me in the right direction @zzzeek. For me it worked
really well to just add these lines to *alembic.autogenerate.render*:
@renderers.dispatch_for(ops.ExecuteSQLOp)
def _execute_sql(autogen_context, op):
assert isinstance(op.sqltext, str)
return 'op.execute({})'.format(op.sqltext)
Is this perhaps something that could be included in alembic? I noticed that
I couldn't make a PR at Bitbucket, so I made one at the github
mirror: https://github.com/zzzeek/alembic/pull/20
On Wednesday, October 28, 2015 at 10:07:14 PM UTC+1, Michael Bayer wrote:
>
>
>
> On 10/28/15 1:57 PM, Jacob Magnusson wrote:
> > Hi,
> >
> > I have a use-case where I need to execute a function called
> > *audit_table* after a new table is created in my migrations. So I
> > thought I would be able to use alembic.operations.ops.ExecuteSQLOp
> > <
> http://alembic.readthedocs.org/en/latest/api/operations.html#alembic.operations.ops.ExecuteSQLOp>,
>
>
> > but I can't find any code that shows me how to actually use it. By
> > reading the API documentation I thought this would be the way:
> >
> >
> > from alembic.autogenerate import rewriter
> > from alembic.operations import ops
> >
> > writer = rewriter.Rewriter()
> >
> > @writer.rewrites(ops.CreateTableOp)
> > def create_table(context, revision, op):
> > return [
> > op,
> > ops.ExecuteSQLOp(
> > sa.select([sa.func.audit_table(op.table_name)])
> > )
> > ]
> >
> > def run_migrations_online():
> > ...
> > context.configure(
> > ...,
> > process_revision_directives=writer,
> >
> >
> > But then I get the following traceback:
> >
> > Traceback (most recent call last):
> > File "/venv/bin/alembic", line 11, in <module>
> > sys.exit(main())
> > File "/venv/lib/python3.5/site-packages/alembic/config.py", line 450,
> > in main
> > CommandLine(prog=prog).main(argv=argv)
> > File "/venv/lib/python3.5/site-packages/alembic/config.py", line 444,
> > in main
> > self.run_cmd(cfg, options)
> > File "/venv/lib/python3.5/site-packages/alembic/config.py", line 427,
> > in run_cmd
> > **dict((k, getattr(options, k)) for k in kwarg)
> > File "/venv/lib/python3.5/site-packages/alembic/command.py", line 121,
> > in revision
> > revision_context.generate_scripts()
> > File "/venv/lib/python3.5/site-packages/alembic/command.py", line 120,
> > in <listcomp>
> > script for script in
> > File "/venv/lib/python3.5/site-packages/alembic/autogenerate/api.py",
> > line 430, in generate_scripts
> > yield self._to_script(generated_revision)
> > File "/venv/lib/python3.5/site-packages/alembic/autogenerate/api.py",
> > line 354, in _to_script
> > autogen_context, migration_script, template_args
> > File
> > "/venv/lib/python3.5/site-packages/alembic/autogenerate/render.py", line
> > 40, in _render_python_into_templatevars
> > _render_cmd_body(upgrade_ops, autogen_context))
> > File
> > "/venv/lib/python3.5/site-packages/alembic/autogenerate/render.py", line
> > 63, in _render_cmd_body
> > lines = render_op(autogen_context, op)
> > File
> > "/venv/lib/python3.5/site-packages/alembic/autogenerate/render.py", line
> > 74, in render_op
> > renderer = renderers.dispatch(op)
> > File "/venv/lib/python3.5/site-packages/alembic/util/langhelpers.py",
> > line 309, in dispatch
> > raise ValueError("no dispatch function for object: %s" % obj)
> > ValueError: no dispatch function for object:
> > <alembic.operations.ops.ExecuteSQLOp object at 0x10f236860>
> >
> > I've also tried to pass in the SQL command as a regular string to
> > ExecuteSQLOp, but I still get the same exception.
> >
> > Could someone tell me what the correct way to use it is? Perhaps I
> > haven't understood correctly what *ExecuteSQLOp* is used for.
>
> ah, wow, OK. Well sure, ExecuteSQLOp is used for executing SQL but it
> currently does not have an "autogenerate" render directive, that is, the
> directive which writes it into a new migration script, since that would
> require writing out all the Python code for
> "sa.select([sa.func.audit_table(op.table_name)])" which is an immensely
> difficult task.
>
> You can build yourself a render function for ExecuteSQLOp following the
> instructions at
>
> http://alembic.readthedocs.org/en/latest/api/autogenerate.html#creating-a-render-function,
>
>
> where you'd have to figure out what Python code you actually want to
> render. Which means you might have an easier time just making yourself
> a RunAuditTableOp object instead so that the way to render in an
> autogenerate script is straightforward.
>
>
>
> >
> > Thanks,
> > Jacob
> >
> > --
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