Add raise/raiseload relationship loading strategypr/193

- available via `lazy='raise'` or by setting the `raiseload` strategy
  via `options()`
- behaves almost like `lazy='noload'`, but instead of returning `None`
  it raises `InvalidRequestError`
- based on code from Mike Bayer that was posted to the sqlalchemy
  mailing list: https://groups.google.com/forum/#!topic/sqlalchemy/X_wA8K97smE

1 files changed, 79 insertions, 0 deletions

diff --git a/test/orm/test_mapper.py b/test/orm/test_mapper.py
index 6845ababb..237371dc7 100644
--- a/test/orm/test_mapper.py
+++ b/test/orm/test_mapper.py
@@ -2717,6 +2717,85 @@ class NoLoadTest(_fixtures.FixtureTest):
         self.sql_count_(0, go)
 
 
+class RaiseLoadTest(_fixtures.FixtureTest):
+    run_inserts = 'once'
+    run_deletes = None
+
+    def test_o2m_raiseload(self):
+        Address, addresses, users, User = (
+            self.classes.Address,
+            self.tables.addresses,
+            self.tables.users,
+            self.classes.User)
+
+        m = mapper(User, users, properties=dict(
+            addresses=relationship(mapper(Address, addresses), lazy='raise')
+        ))
+        q = create_session().query(m)
+        l = [None]
+
+        def go():
+            x = q.filter(User.id == 7).all()
+            assert_raises_message(
+                sa.exc.InvalidRequestError,
+                "'User.addresses' is not available due to lazy='raise'",
+                lambda: x[0].addresses)
+            l[0] = x
+            print(x)
+        self.assert_sql_count(testing.db, go, 1)
+
+        self.assert_result(
+            l[0], User,
+            {'id': 7},
+        )
+
+    def test_upgrade_o2m_raiseload_lazyload_option(self):
+        Address, addresses, users, User = (
+            self.classes.Address,
+            self.tables.addresses,
+            self.tables.users,
+            self.classes.User)
+
+        m = mapper(User, users, properties=dict(
+            addresses=relationship(mapper(Address, addresses), lazy='raise')
+        ))
+        q = create_session().query(m).options(sa.orm.lazyload('addresses'))
+        l = [None]
+
+        def go():
+            x = q.filter(User.id == 7).all()
+            x[0].addresses
+            l[0] = x
+        self.sql_count_(2, go)
+
+        self.assert_result(
+            l[0], User,
+            {'id': 7, 'addresses': (Address, [{'id': 1}])},
+        )
+
+    def test_m2o_raiseload_option(self):
+        Address, addresses, users, User = (
+            self.classes.Address,
+            self.tables.addresses,
+            self.tables.users,
+            self.classes.User)
+        mapper(Address, addresses, properties={
+            'user': relationship(User)
+        })
+        mapper(User, users)
+        s = Session()
+        a1 = s.query(Address).filter_by(id=1).options(
+            sa.orm.raiseload('user')).first()
+
+        def go():
+            assert_raises_message(
+                sa.exc.InvalidRequestError,
+                "'Address.user' is not available due to lazy='raise'",
+                lambda: a1.user)
+
+        self.sql_count_(0, go)
+
+
 class RequirementsTest(fixtures.MappedTest):
 
     """Tests the contract for user classes."""