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 > > -- > You received this message because you are subscribed to the Google > Groups "sqlalchemy-alembic" group. > To unsubscribe from this group and stop receiving emails from it, send > an email to sqlalchemy-alembic+unsubscr...@googlegroups.com > <mailto:sqlalchemy-alembic+unsubscr...@googlegroups.com>. > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "sqlalchemy-alembic" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy-alembic+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
