- Added support for parameter-ordered SET clauses in an UPDATE

statement.  This feature is available by passing the
:paramref:`~.sqlalchemy.sql.expression.update.preserve_parameter_order`
flag either to the core :class:`.Update` construct or alternatively
adding it to the :paramref:`.Query.update.update_args` dictionary at
the ORM-level, also passing the parameters themselves as a list of 2-tuples.
Thanks to Gorka Eguileor for implementation and tests.
adapted from pullreq github:200

1 files changed, 12 insertions, 1 deletions

diff --git a/lib/sqlalchemy/sql/crud.py b/lib/sqlalchemy/sql/crud.py
index 72b66c036..67a8f09de 100644
--- a/lib/sqlalchemy/sql/crud.py
+++ b/lib/sqlalchemy/sql/crud.py
@@ -208,7 +208,18 @@ def _scan_cols(
         implicit_return_defaults, postfetch_lastrowid = \
         _get_returning_modifiers(compiler, stmt)
 
-    cols = stmt.table.columns
+    if stmt._parameter_ordering:
+        parameter_ordering = [
+            _column_as_key(key) for key in stmt._parameter_ordering
+        ]
+        ordered_keys = set(parameter_ordering)
+        cols = [
+            stmt.table.c[key] for key in parameter_ordering
+        ] + [
+            c for c in stmt.table.c if c.key not in ordered_keys
+        ]
+    else:
+        cols = stmt.table.columns
 
     for c in cols:
         col_key = _getattr_col_key(c)