call setinputsizes for cx_Oracle.DATETIME

Restored adding cx_Oracle.DATETIME to the setinputsizes() call when a
SQLAlchemy :class:`.Date`, :class:`.DateTime` or :class:`.Time` datatype is
used, so that in the case where a bound parameter is passed as NULL
in some complex queries (in particular this happens with some lazy load
situations), the type is still present.  This was removed
in the 1.2 series for arbitrary reasons.

Also adds a suite test for this generic situation.

What's not clear is that do we really need setinputsizes() for all
datatypes if we are supporting NULL in bound parameters.

Fixes: #4886
Change-Id: If99215c31861f9ea6f60a30d47f2f320adc4797f

2 files changed, 37 insertions, 0 deletions

diff --git a/lib/sqlalchemy/testing/requirements.py b/lib/sqlalchemy/testing/requirements.py
index ca7a42db4..62e442b6b 100644
--- a/lib/sqlalchemy/testing/requirements.py
+++ b/lib/sqlalchemy/testing/requirements.py
@@ -193,6 +193,14 @@ class SuiteRequirements(Requirements):
         return exclusions.closed()
 
     @property
+    def standalone_null_binds_whereclause(self):
+        """target database/driver supports bound parameters with NULL in the
+        WHERE clause, in situations where it has to be typed.
+
+        """
+        return exclusions.open()
+
+    @property
     def intersect(self):
         """Target database must support INTERSECT or equivalent."""
         return exclusions.closed()
diff --git a/lib/sqlalchemy/testing/suite/test_types.py b/lib/sqlalchemy/testing/suite/test_types.py
index 37428c545..435ab4689 100644
--- a/lib/sqlalchemy/testing/suite/test_types.py
+++ b/lib/sqlalchemy/testing/suite/test_types.py
@@ -14,7 +14,9 @@ from ..schema import Column
 from ..schema import Table
 from ... import and_
 from ... import BigInteger
+from ... import bindparam
 from ... import Boolean
+from ... import case
 from ... import cast
 from ... import Date
 from ... import DateTime
@@ -291,6 +293,33 @@ class _DateFixture(_LiteralRoundTripFixture):
         compare = self.compare or self.data
         self._literal_round_trip(self.datatype, [self.data], [compare])
 
+    @testing.requires.standalone_null_binds_whereclause
+    def test_null_bound_comparison(self):
+        # this test is based on an Oracle issue observed in #4886.
+        # passing NULL for an expression that needs to be interpreted as
+        # a certain type, does the DBAPI have the info it needs to do this.
+        date_table = self.tables.date_table
+        with config.db.connect() as conn:
+            result = conn.execute(
+                date_table.insert(), {"date_data": self.data}
+            )
+            id_ = result.inserted_primary_key[0]
+            stmt = select([date_table.c.id]).where(
+                case(
+                    [
+                        (
+                            bindparam("foo", type_=self.datatype) != None,
+                            bindparam("foo", type_=self.datatype),
+                        )
+                    ],
+                    else_=date_table.c.date_data,
+                )
+                == date_table.c.date_data
+            )
+
+            row = conn.execute(stmt, {"foo": None}).first()
+            eq_(row[0], id_)
+
 
 class DateTimeTest(_DateFixture, fixtures.TablesTest):
     __requires__ = ("datetime",)