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-rw-r--r--lib/sqlalchemy/sql/coercions.py21
1 files changed, 21 insertions, 0 deletions
diff --git a/lib/sqlalchemy/sql/coercions.py b/lib/sqlalchemy/sql/coercions.py
index 3b972be41..d4b208c56 100644
--- a/lib/sqlalchemy/sql/coercions.py
+++ b/lib/sqlalchemy/sql/coercions.py
@@ -437,6 +437,20 @@ class ExpressionElementImpl(_ColumnCoercions, RoleImpl):
except exc.ArgumentError as err:
self._raise_for_expected(element, err=err)
+ def _raise_for_expected(self, element, argname=None, resolved=None, **kw):
+ if isinstance(element, roles.AnonymizedFromClauseRole):
+ advice = (
+ "To create a "
+ "column expression from a FROM clause row "
+ "as a whole, use the .table_valued() method."
+ )
+ else:
+ advice = None
+
+ return super(ExpressionElementImpl, self)._raise_for_expected(
+ element, argname=argname, resolved=resolved, advice=advice, **kw
+ )
+
class BinaryElementImpl(ExpressionElementImpl, RoleImpl):
@@ -603,6 +617,13 @@ class ColumnArgumentOrKeyImpl(_ReturnsStringKey, RoleImpl):
__slots__ = ()
+class StrAsPlainColumnImpl(_CoerceLiterals, RoleImpl):
+ __slots__ = ()
+
+ def _text_coercion(self, element, argname=None):
+ return elements.ColumnClause(element)
+
+
class ByOfImpl(_CoerceLiterals, _ColumnCoercions, RoleImpl, roles.ByOfRole):
__slots__ = ()