Provide query_class via backref for legacy use

pyproject.toml

@@ -113,7 +113,6 @@ required_plugins = [
 minversion = '6.0'
 addopts = '--doctest-modules --ignore setup.py --cov-report=term-missing'
 doctest_optionflags = ['ALLOW_UNICODE', 'ALLOW_BYTES']
-filterwarnings = ['ignore::DeprecationWarning', 'ignore::UserWarning']
 env = ['FLASK_ENV=testing']
 remote_data_strict = true
 

src/coaster/sqlalchemy/model.py

@@ -70,6 +70,7 @@ class Other(Model):
 from sqlalchemy.dialects import postgresql
 from sqlalchemy.orm import DeclarativeBase
 from sqlalchemy.orm import Query as QueryBase
+from sqlalchemy.orm import backref as backref_base
 from sqlalchemy.orm import mapped_column
 from sqlalchemy.orm import relationship as relationship_base
 from sqlalchemy.orm.dynamic import AppenderMixin
@@ -88,9 +89,11 @@ class Other(Model):
     'timestamp_now',
     'jsonb',
     'Query',
+    'QueryProperty',
     'ModelBase',
     'DeclarativeBase',
     'relationship',
+    'backref',
 ]
 
 
@@ -377,3 +380,4 @@ def wrapper(*args: _P.args, **kwargs: _P.kwargs) -> _T:
 #: Wrap :func:`~sqlalchemy.orm.relationship` to insert a default query_class compatible
 #: with Flask-SQLAlchemy's
 relationship = _create_relationship_wrapper(relationship_base)
+backref = _create_relationship_wrapper(backref_base)

tests/coaster_tests/sqlalchemy_modelbase_test.py

@@ -16,6 +16,7 @@
     ModelBase,
     ModelWarning,
     Query,
+    backref,
     int_pkey,
     relationship,
 )
@@ -339,6 +340,32 @@ class RelatedModel(Model):  # skipcq: PTC-W0065
     assert isinstance(TestModel().related, Query)
 
 
+def test_backref_query_class() -> None:
+    """Relationships via backref get Coaster's Query."""
+
+    class Model(ModelBase, DeclarativeBase):
+        """Test Model base."""
+
+    class TestModel(Model):
+        """Test model."""
+
+        __tablename__ = 'test_model'
+        pkey: Mapped[int_pkey]
+
+    class RelatedModel(Model):  # pylint: disable=unused-variable # skipcq: PTC-W0065
+        """Related model."""
+
+        __tablename__ = 'related_model'
+        pkey: Mapped[int_pkey]
+        test_id: Mapped[int] = mapped_column(sa.ForeignKey('test_model.pkey'))
+        with pytest.warns(ModelWarning):
+            test: Mapped[TestModel] = relationship(
+                backref=backref('related', lazy='dynamic')
+            )
+
+    assert isinstance(TestModel().related, Query)  # type: ignore[attr-defined]
+
+
 def test_backref_warning() -> None:
     """Relationships using a backref raise a warning."""