feat: add app handler methods save_setting(), delete_setting()

src/wuttjamaican/app.py

@@ -370,14 +370,16 @@ class AppHandler:
 
     def get_setting(self, session, name, **kwargs):
         """
-        Get a setting value from the DB.
+        Get a :term:`config setting` value from the DB.
 
-        This does *not* consult the config object directly to
+        This does *not* consult the :term:`config object` directly to
         determine the setting value; it always queries the DB.
 
         Default implementation is just a convenience wrapper around
         :func:`~wuttjamaican.db.conf.get_setting()`.
 
+        See also :meth:`save_setting()` and :meth:`delete_setting()`.
+
         :param session: App DB session.
 
         :param name: Name of the setting to get.
@@ -388,6 +390,65 @@ class AppHandler:
 
         return get_setting(session, name)
 
+    def save_setting(
+            self,
+            session,
+            name,
+            value,
+            force_create=False,
+    ):
+        """
+        Save a :term:`config setting` value to the DB.
+
+        See also :meth:`get_setting()` and :meth:`delete_setting()`.
+
+        :param session: Current :term:`db session`.
+
+        :param name: Name of the setting to save.
+
+        :param value: Value to be saved for the setting; should be
+           either a string or ``None``.
+
+        :param force_create: If ``False`` (the default) then logic
+           will first try to locate an existing setting of the same
+           name, and update it if found, or create if not.
+
+           But if this param is ``True`` then logic will only try to
+           create a new record, and not bother checking to see if it
+           exists.
+
+           (Theoretically the latter offers a slight efficiency gain.)
+        """
+        model = self.model
+
+        # maybe fetch existing setting
+        setting = None
+        if not force_create:
+            setting = session.get(model.Setting, name)
+
+        # create setting if needed
+        if not setting:
+            setting = model.Setting(name=name)
+            session.add(setting)
+
+        # set value
+        setting.value = value
+
+    def delete_setting(self, session, name):
+        """
+        Delete a :term:`config setting` from the DB.
+
+        See also :meth:`get_setting()` and :meth:`save_setting()`.
+
+        :param session: Current :term:`db session`.
+
+        :param name: Name of the setting to delete.
+        """
+        model = self.model
+        setting = session.get(model.Setting, name)
+        if setting:
+            session.delete(setting)
+
     ##############################
     # getters for other handlers
     ##############################

tests/test_app.py

@@ -97,6 +97,68 @@ class TestAppHandler(TestCase):
         value = self.app.get_setting(session, 'foo')
         self.assertEqual(value, 'bar')
 
+    def test_save_setting(self):
+        try:
+            import sqlalchemy as sa
+            from sqlalchemy import orm
+        except ImportError:
+            pytest.skip("test is not relevant without sqlalchemy")
+
+        Session = orm.sessionmaker()
+        engine = sa.create_engine('sqlite://')
+        session = Session(bind=engine)
+        session.execute(sa.text("""
+        create table setting (
+                name varchar(255) primary key,
+                value text
+        );
+        """))
+        session.commit()
+
+        # value null by default
+        value = self.app.get_setting(session, 'foo')
+        self.assertIsNone(value)
+
+        # unless we save a value
+        self.app.save_setting(session, 'foo', '1')
+        session.commit()
+        value = self.app.get_setting(session, 'foo')
+        self.assertEqual(value, '1')
+
+    def test_delete_setting(self):
+        try:
+            import sqlalchemy as sa
+            from sqlalchemy import orm
+        except ImportError:
+            pytest.skip("test is not relevant without sqlalchemy")
+
+        Session = orm.sessionmaker()
+        engine = sa.create_engine('sqlite://')
+        session = Session(bind=engine)
+        session.execute(sa.text("""
+        create table setting (
+                name varchar(255) primary key,
+                value text
+        );
+        """))
+        session.commit()
+
+        # value null by default
+        value = self.app.get_setting(session, 'foo')
+        self.assertIsNone(value)
+
+        # unless we save a value
+        self.app.save_setting(session, 'foo', '1')
+        session.commit()
+        value = self.app.get_setting(session, 'foo')
+        self.assertEqual(value, '1')
+
+        # but then if we delete it, should be null again
+        self.app.delete_setting(session, 'foo')
+        session.commit()
+        value = self.app.get_setting(session, 'foo')
+        self.assertIsNone(value)
+
     def test_model(self):
         try:
             from wuttjamaican.db import model