- 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

2 files changed, 20 insertions, 6 deletions

diff --git a/lib/sqlalchemy/orm/persistence.py b/lib/sqlalchemy/orm/persistence.py
index 1f9d0a235..768c1146a 100644
--- a/lib/sqlalchemy/orm/persistence.py
+++ b/lib/sqlalchemy/orm/persistence.py
@@ -1258,10 +1258,16 @@ class BulkUpdate(BulkUD):
                 "Invalid expression type: %r" % key)
 
     def _do_exec(self):
-        values = dict(
+
+        values = [
             (self._resolve_string_to_expr(k), v)
-            for k, v in self.values.items()
-        )
+            for k, v in (
+                self.values.items() if hasattr(self.values, 'items')
+                else self.values)
+        ]
+        if not self.update_kwargs.get('preserve_parameter_order', False):
+            values = dict(values)
+
         update_stmt = sql.update(self.primary_table,
                                  self.context.whereclause, values,
                                  **self.update_kwargs)
@@ -1311,7 +1317,9 @@ class BulkUpdateEvaluate(BulkEvaluate, BulkUpdate):
 
     def _additional_evaluators(self, evaluator_compiler):
         self.value_evaluators = {}
-        for key, value in self.values.items():
+        values = (self.values.items() if hasattr(self.values, 'items')
+                  else self.values)
+        for key, value in values:
             key = self._resolve_key_to_attrname(key)
             if key is not None:
                 self.value_evaluators[key] = evaluator_compiler.process(
diff --git a/lib/sqlalchemy/orm/query.py b/lib/sqlalchemy/orm/query.py
index 84fb04d80..4441975bf 100644
--- a/lib/sqlalchemy/orm/query.py
+++ b/lib/sqlalchemy/orm/query.py
@@ -2910,7 +2910,12 @@ class Query(object):
 
         :param values: a dictionary with attributes names, or alternatively
          mapped attributes or SQL expressions, as keys, and literal
-         values or sql expressions as values.
+         values or sql expressions as values.   If :ref:`parameter-ordered
+         mode <updates_order_parameters>` is desired, the values can be
+         passed as a list of 2-tuples;
+         this requires that the :paramref:`~sqlalchemy.sql.expression.update.preserve_parameter_order`
+         flag is passed to the :paramref:`.Query.update.update_args` dictionary
+         as well.
 
           .. versionchanged:: 1.0.0 - string names in the values dictionary
              are now resolved against the mapped entity; previously, these
@@ -2941,7 +2946,8 @@ class Query(object):
         :param update_args: Optional dictionary, if present will be passed
          to the underlying :func:`.update` construct as the ``**kw`` for
          the object.  May be used to pass dialect-specific arguments such
-         as ``mysql_limit``.
+         as ``mysql_limit``, as well as other special arguments such as
+         :paramref:`~sqlalchemy.sql.expression.update.preserve_parameter_order`.
 
          .. versionadded:: 1.0.0