Method from_config

alembic/script/base.py:161–201

Produce a new :class:`.ScriptDirectory` given a :class:`.Config` instance. The :class:`.Config` need only have the ``script_location`` key present.

(cls, config: Config)

    @classmethod
    def from_config(cls, config: Config) -> ScriptDirectory:
        """Produce a new :class:`.ScriptDirectory` given a :class:`.Config`
        instance.

        The :class:`.Config` need only have the ``script_location`` key
        present.

        """
        script_location = config.get_alembic_option("script_location")
        if script_location is None:
            raise util.CommandError(
                "No 'script_location' key found in configuration."
            )
        truncate_slug_length: Optional[int]
        tsl = config.get_alembic_option("truncate_slug_length")
        if tsl is not None:
            truncate_slug_length = int(tsl)
        else:
            truncate_slug_length = None

        prepend_sys_path = config.get_prepend_sys_paths_list()
        if prepend_sys_path:
            sys.path[:0] = prepend_sys_path

        rvl = config.get_alembic_boolean_option("recursive_version_locations")
        return ScriptDirectory(
            util.coerce_resource_to_filename(script_location),
            file_template=config.get_alembic_option(
                "file_template", _default_file_template
            ),
            truncate_slug_length=truncate_slug_length,
            sourceless=config.get_alembic_boolean_option("sourceless"),
            output_encoding=config.get_alembic_option(
                "output_encoding", "utf-8"
            ),
            version_locations=config.get_version_locations_list(),
            timezone=config.get_alembic_option("timezone"),
            hooks=config.get_hooks_list(),
            recursive_version_locations=rvl,
            messaging_opts=config.messaging_opts,
        )

    @contextmanager
    def _catch_revision_errors(