Remove ORM elements from annotations at the schema level.

Fixed issue where when constructing constraints from ORM-bound columns,
primarily :class:`.ForeignKey` objects but also :class:`.UniqueConstraint`,
:class:`.CheckConstraint` and others, the ORM-level
:class:`.InstrumentedAttribute` is discarded entirely, and all ORM-level
annotations from the columns are removed; this is so that the constraints
are still fully pickleable without the ORM-level entities being pulled in.
These annotations are not necessary to be present at the schema/metadata
level.

Fully implemented coercions for constraint columns within
schema.py, including for FK referenced columns.

Fixes: #5001
Change-Id: I895400dd979310be034085d207f096707c635909

1 files changed, 8 insertions, 3 deletions

diff --git a/lib/sqlalchemy/sql/elements.py b/lib/sqlalchemy/sql/elements.py
index ba615bc3f..eda31dc61 100644
--- a/lib/sqlalchemy/sql/elements.py
+++ b/lib/sqlalchemy/sql/elements.py
@@ -3246,7 +3246,7 @@ class BinaryExpression(ColumnElement):
         # refer to BinaryExpression directly and pass strings
         if isinstance(operator, util.string_types):
             operator = operators.custom_op(operator)
-        self._orig = (left, right)
+        self._orig = (hash(left), hash(right))
         self.left = left.self_group(against=operator)
         self.right = right.self_group(against=operator)
         self.operator = operator
@@ -3261,7 +3261,7 @@ class BinaryExpression(ColumnElement):
 
     def __bool__(self):
         if self.operator in (operator.eq, operator.ne):
-            return self.operator(hash(self._orig[0]), hash(self._orig[1]))
+            return self.operator(self._orig[0], self._orig[1])
         else:
             raise TypeError("Boolean value of this clause is not defined")
 
@@ -3946,7 +3946,12 @@ class Label(HasMemoized, roles.LabeledColumnExprRole, ColumnElement):
         return key, e
 
 
-class ColumnClause(roles.LabeledColumnExprRole, Immutable, ColumnElement):
+class ColumnClause(
+    roles.DDLReferredColumnRole,
+    roles.LabeledColumnExprRole,
+    Immutable,
+    ColumnElement,
+):
     """Represents a column expression from any textual string.
 
     The :class:`.ColumnClause`, a lightweight analogue to the