Make save parameter of set_multivalue public

It can be useful for performance when setting values for MultiValue field on a
large set of records.

issue6625
review39491002

doc/ref/models/models.rst

@@ -737,9 +737,12 @@ Instance methods:
 
     Return the value of the field `name` for the pattern.
 
-.. method:: MultiValueMixin.set_multivalue(name, value, \*\*pattern)
+.. method:: MultiValueMixin.set_multivalue(name, value[, save], \*\*pattern)
 
     Store the value of the field `name` for the pattern.
+    If `save` is true, it will be stored in the database, otherwise the
+    modified :class:`ValueMixin` records are returned unsaved. `save` is true
+    by default.
 
 .. warning::
     To customize the pattern, both methods must be override the same way.

trytond/model/multivalue.py

@@ -60,14 +60,14 @@ class MultiValueMixin(object):
         else:
             return value
 
-    def set_multivalue(self, name, value, _save=True, **pattern):
+    def set_multivalue(self, name, value, save=True, **pattern):
         Value = self.multivalue_model(name)
         values = self.__values(name, pattern, match_none=True)
         if not values:
             values = [self.multivalue_record(name, **pattern)]
         for record in values:
             setattr(record, name, value)
-        if _save:
+        if save:
             Value.save(values)
         else:
             return values
@@ -77,7 +77,7 @@ class MultiValueMixin(object):
         Value = cls.multivalue_model(name)
         to_save = []
         for record in records:
-            to_save.extend(record.set_multivalue(name, val, _save=False))
+            to_save.extend(record.set_multivalue(name, val, save=False))
         Value.save(to_save)