sqlalchemy-engine-default-defaultdialect.markdown

title: sqlalchemy.engine.default DefaultDialect Example Code category: page slug: sqlalchemy-engine-default-defaultdialect-examples sortorder: 500031026 toc: False sidebartitle: sqlalchemy.engine.default DefaultDialect meta: Example code for understanding how to use the DefaultDialect class from the sqlalchemy.engine.default module of the SQLAlchemy project.

DefaultDialect is a class within the sqlalchemy.engine.default module of the SQLAlchemy project.

Example 1 from alembic

Alembic (project documentation and PyPI page) is a data migrations tool used with SQLAlchemy to make database schema changes. The Alembic project is open sourced under the MIT license.

alembic / alembic / autogenerate / api.py

# api.py
    )

    compare._populate_migration_script(autogen_context, migration_script)

    return migration_script


def render_python_code(
    up_or_down_op,
    sqlalchemy_module_prefix="sa.",
    alembic_module_prefix="op.",
    render_as_batch=False,
    imports=(),
    render_item=None,
    migration_context=None,
):
    opts = {
        "sqlalchemy_module_prefix": sqlalchemy_module_prefix,
        "alembic_module_prefix": alembic_module_prefix,
        "render_item": render_item,
        "render_as_batch": render_as_batch,
    }

    if migration_context is None:
        from ..runtime.migration import MigrationContext
~~        from sqlalchemy.engine.default import DefaultDialect

        migration_context = MigrationContext.configure(
~~            dialect=DefaultDialect()
        )

    autogen_context = AutogenContext(migration_context, opts=opts)
    autogen_context.imports = set(imports)
    return render._indent(
        render._render_cmd_body(up_or_down_op, autogen_context)
    )


def _render_migration_diffs(context, template_args):

    autogen_context = AutogenContext(context)

    upgrade_ops = ops.UpgradeOps([])
    compare._produce_net_changes(autogen_context, upgrade_ops)

    migration_script = ops.MigrationScript(
        rev_id=None,
        upgrade_ops=upgrade_ops,
        downgrade_ops=upgrade_ops.reverse(),
    )

    render._render_python_into_templatevars(
        autogen_context, migration_script, template_args


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