Re: Using a 3rd Party Dialect

mike bayer Fri, 10 Mar 2017 11:57:01 -0800

env.py is the place to put it, because Alembic commands will run env.pyat the start of an operation (assuming it's an operation for which theenvironment is started up) and the class definition will immediatelyregister the dialect.

Feel free to provide more specifics what commands you're running andwhat symptoms of "not registered" you're seeing.




On 03/10/2017 01:42 PM, Kayvon Raphael wrote:

Hi there - is there a specific place to add that class so that it gets
picked up by alembic? Added to env.py but did not get registered

Thanks




On Saturday, November 1, 2014 at 10:40:05 AM UTC-4, Michael Bayer wrote:

    alembic doesn’t have a formally published extension API as of yet,
    to get that to work you’d need to make an Impl:


    from alembic.ddl.postgresql import PostgresqlImpl

    class RedshiftImpl(PostgresqlImpl):
        __dialect__ = ‘redshift’


    that will register the name “redshift” into alembic’s lookup.

    On Oct 31, 2014, at 4:34 PM, Daniel Son <[email protected]
    <javascript:>> wrote:

    Hi,
    I'm new to SQLalchemy and alembic and I'm doing a proof of concept
    for migrations in Redshift.

    Initially, using the regular postgresql dialect everything is fine.
    But when I try to use the redshift_sqlalchemy dialect for the last
    bit of Redshift functionality, it goes caput.
    And I've looked over SQLAlchemy and Alembic docs for any help on
    using 3rd Party dialects and I can't seem to get anywhere.

    Environment:
    The basic setup as told by the Tutorial

    The following are installed in a virtualenv:
    pip install alembic
    pip install psycopg2
    pip install redshift_sqlalchemy

    I've tried to manually register the dialect:
    from sqlalchemy.dialects import registry
    registry.register("redshift", "redshift_sqlalchemy.dialect",
    "RedshiftDialect")
    registry.register("redshift.psycopg2",
    "redshift_sqlalchemy.dialect", "RedshiftDialect")

    And tried the following url setups in my alembic.ini (via alembic
    init)
    sqlalchemy.url = redshift+psycopg2://user:pass@host:port/dbname
    sqlalchemy.url = redshift://user:pass@host:port/dbname

    Both error out the same as this trace out.

    Traceback (most recent call last):
      File "/opt/virtualenvs/alembic/bin/alembic", line 9, in <module>
        load_entry_point('alembic==0.6.7', 'console_scripts', 'alembic')()
      File
    "/opt/virtualenvs/alembic/lib/python2.7/site-packages/alembic/config.py",
    line 306, in main
        CommandLine(prog=prog).main(argv=argv)
      File
    "/opt/virtualenvs/alembic/lib/python2.7/site-packages/alembic/config.py",
    line 300, in main
        self.run_cmd(cfg, options)
      File
    "/opt/virtualenvs/alembic/lib/python2.7/site-packages/alembic/config.py",
    line 286, in run_cmd
        **dict((k, getattr(options, k)) for k in kwarg)
      File
    "/opt/virtualenvs/alembic/lib/python2.7/site-packages/alembic/command.py",
    line 129, in upgrade
        script.run_env()
      File
    "/opt/virtualenvs/alembic/lib/python2.7/site-packages/alembic/script.py",
    line 208, in run_env
        util.load_python_file(self.dir, 'env.py')
      File
    "/opt/virtualenvs/alembic/lib/python2.7/site-packages/alembic/util.py",
    line 230, in load_python_file
        module = load_module_py(module_id, path)
      File
    "/opt/virtualenvs/alembic/lib/python2.7/site-packages/alembic/compat.py",
    line 63, in load_module_py
        mod = imp.load_source(module_id, path, fp)
      File "dson_test/env.py", line 92, in <module>
        run_migrations_online()
      File "dson_test/env.py", line 80, in run_migrations_online
        target_metadata=target_metadata
      File "<string>", line 7, in configure
      File
    
"/opt/virtualenvs/alembic/lib/python2.7/site-packages/alembic/environment.py",
    line 672, in configure
        opts=opts
      File
    "/opt/virtualenvs/alembic/lib/python2.7/site-packages/alembic/migration.py",
    line 158, in configure
        return MigrationContext(dialect, connection, opts,
    environment_context)
      File
    "/opt/virtualenvs/alembic/lib/python2.7/site-packages/alembic/migration.py",
    line 103, in __init__
        self.impl = ddl.DefaultImpl.get_by_dialect(dialect)(
      File
    "/opt/virtualenvs/alembic/lib/python2.7/site-packages/alembic/ddl/impl.py",
    line 55, in get_by_dialect
        return _impls[dialect.name <http://dialect.name>]
    KeyError: 'redshift'

    What am I missing?

    Thanks,
    Daniel

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Re: Using a 3rd Party Dialect

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