extract() is now dialect-sensitive and supports SQLite and others.

1 files changed, 22 insertions, 2 deletions

diff --git a/lib/sqlalchemy/sql/expression.py b/lib/sqlalchemy/sql/expression.py
index 5a0d5b043..56f358db8 100644
--- a/lib/sqlalchemy/sql/expression.py
+++ b/lib/sqlalchemy/sql/expression.py
@@ -484,8 +484,7 @@ def cast(clause, totype, **kwargs):
 def extract(field, expr):
     """Return the clause ``extract(field FROM expr)``."""
 
-    expr = _BinaryExpression(text(field), expr, operators.from_)
-    return func.extract(expr)
+    return _Extract(field, expr)
 
 def collate(expression, collation):
     """Return the clause ``expression COLLATE collation``."""
@@ -2313,6 +2312,27 @@ class _Cast(ColumnElement):
         return self.clause._from_objects
 
 
+class _Extract(ColumnElement):
+
+    __visit_name__ = 'extract'
+
+    def __init__(self, field, expr, **kwargs):
+        self.type = sqltypes.Integer()
+        self.field = field
+        self.expr = _literal_as_binds(expr, None)
+
+    def _copy_internals(self, clone=_clone):
+        self.field = clone(self.field)
+        self.expr = clone(self.expr)
+
+    def get_children(self, **kwargs):
+        return self.field, self.expr
+
+    @property
+    def _from_objects(self):
+        return self.expr._from_objects
+
+
 class _UnaryExpression(ColumnElement):
 
     __visit_name__ = 'unary'