fix: add util module, w/ model_transaction_query()

just a basic implementation, will have to improve later

src/wutta_continuum/util.py

@@ -0,0 +1,85 @@
+# -*- coding: utf-8; -*-
+################################################################################
+#
+#  Wutta-Continuum -- SQLAlchemy Versioning for Wutta Framework
+#  Copyright © 2024-2025 Lance Edgar
+#
+#  This file is part of Wutta Framework.
+#
+#  Wutta Framework is free software: you can redistribute it and/or modify it
+#  under the terms of the GNU General Public License as published by the Free
+#  Software Foundation, either version 3 of the License, or (at your option) any
+#  later version.
+#
+#  Wutta Framework is distributed in the hope that it will be useful, but
+#  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+#  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+#  more details.
+#
+#  You should have received a copy of the GNU General Public License along with
+#  Wutta Framework.  If not, see <http://www.gnu.org/licenses/>.
+#
+################################################################################
+"""
+SQLAlchemy-Continuum utilities
+"""
+
+import sqlalchemy as sa
+from sqlalchemy import orm
+import sqlalchemy_continuum as continuum
+
+
+OPERATION_TYPES = {
+    continuum.Operation.INSERT: "INSERT",
+    continuum.Operation.UPDATE: "UPDATE",
+    continuum.Operation.DELETE: "DELETE",
+}
+
+
+def render_operation_type(operation_type):
+    """
+    Render a SQLAlchemy-Continuum ``operation_type`` from a version
+    record, for display to user.
+
+    :param operation_type: Value of same name from a version record.
+       Must be one of:
+
+       * :attr:`sqlalchemy_continuum:sqlalchemy_continuum.operation.Operation.INSERT`
+       * :attr:`sqlalchemy_continuum:sqlalchemy_continuum.operation.Operation.UPDATE`
+       * :attr:`sqlalchemy_continuum:sqlalchemy_continuum.operation.Operation.DELETE`
+
+    :returns: Display name for the operation type, as string.
+    """
+    return OPERATION_TYPES[operation_type]
+
+
+def model_transaction_query(instance, session=None, model_class=None):
+    """
+    Make a query capable of finding all SQLAlchemy-Continuum
+    ``transaction`` records associated with the given model instance.
+
+    :param instance: Instance of a versioned :term:`data model`.
+
+    :param session: Optional :term:`db session` to use for the query.
+       If not specified, will be obtained from the ``instance``.
+
+    :param model_class: Optional :term:`data model` class to query.
+       If not specified, will be obtained from the ``instance``.
+
+    :returns: SQLAlchemy query object.  Note that it will *not* have an
+       ``ORDER BY`` clause yet.
+    """
+    if not session:
+        session = orm.object_session(instance)
+    if not model_class:
+        model_class = type(instance)
+
+    txncls = continuum.transaction_class(model_class)
+    vercls = continuum.version_class(model_class)
+
+    query = session.query(txncls).join(
+        vercls,
+        sa.and_(vercls.uuid == instance.uuid, vercls.transaction_id == txncls.id),
+    )
+
+    return query