- A :func:`.bindparam` construct with a "null" type (e.g. no type

specified) is now copied when used in a typed expression, and the
new copy is assigned the actual type of the compared column.  Previously,
this logic would occur on the given :func:`.bindparam` in place.
Additionally, a similar process now occurs for :func:`.bindparam` constructs
passed to :meth:`.ValuesBase.values` for a :class:`.Insert` or
:class:`.Update` construct. [ticket:2850]

1 files changed, 1 insertions, 4 deletions

diff --git a/lib/sqlalchemy/sql/default_comparator.py b/lib/sqlalchemy/sql/default_comparator.py
index c9125108a..7c803ac4c 100644
--- a/lib/sqlalchemy/sql/default_comparator.py
+++ b/lib/sqlalchemy/sql/default_comparator.py
@@ -261,10 +261,7 @@ class _DefaultColumnComparator(operators.ColumnOperators):
         if isinstance(other, (ColumnElement, TextClause)):
             if isinstance(other, BindParameter) and \
                     other.type._isnull:
-                # TODO: perhaps we should not mutate the incoming
-                # bindparam() here and instead make a copy of it.
-                # this might be the only place that we're mutating
-                # an incoming construct.
+                other = other._clone()
                 other.type = expr.type
             return other
         elif hasattr(other, '__clause_element__'):