Merge "Infer types in BindParameter when expanding=True"

2 files changed, 25 insertions, 2 deletions

diff --git a/lib/sqlalchemy/sql/elements.py b/lib/sqlalchemy/sql/elements.py
index dfa6c0f8f..9e1b69088 100644
--- a/lib/sqlalchemy/sql/elements.py
+++ b/lib/sqlalchemy/sql/elements.py
@@ -1392,15 +1392,26 @@ class BindParameter(roles.InElementRole, ColumnElement):
         self.literal_execute = literal_execute
         if _is_crud:
             self._is_crud = True
+
         if type_ is None:
+            if expanding and value:
+                check_value = value[0]
+            else:
+                check_value = value
             if _compared_to_type is not None:
                 self.type = _compared_to_type.coerce_compared_value(
-                    _compared_to_operator, value
+                    _compared_to_operator, check_value
                 )
             else:
-                self.type = type_api._resolve_value_to_type(value)
+                self.type = type_api._resolve_value_to_type(check_value)
         elif isinstance(type_, type):
             self.type = type_()
+        elif type_._is_tuple_type:
+            if expanding and value:
+                check_value = value[0]
+            else:
+                check_value = value
+            self.type = type_._resolve_values_to_types(check_value)
         else:
             self.type = type_
 
diff --git a/lib/sqlalchemy/sql/sqltypes.py b/lib/sqlalchemy/sql/sqltypes.py
index e57a14681..bdfb7d833 100644
--- a/lib/sqlalchemy/sql/sqltypes.py
+++ b/lib/sqlalchemy/sql/sqltypes.py
@@ -2912,8 +2912,20 @@ class TupleType(TypeEngine):
     _is_tuple_type = True
 
     def __init__(self, *types):
+        self._fully_typed = NULLTYPE not in types
         self.types = types
 
+    def _resolve_values_to_types(self, value):
+        if self._fully_typed:
+            return self
+        else:
+            return TupleType(
+                *[
+                    _resolve_value_to_type(elem) if typ is NULLTYPE else typ
+                    for typ, elem in zip(self.types, value)
+                ]
+            )
+
     def result_processor(self, dialect, coltype):
         raise NotImplementedError(
             "The tuple type does not support being fetched "