Ticket #18044: django-efficient-save.patch

django/db/models/sql/compiler.py

@@ -944 +944 @@
         result = ['UPDATE %s' % qn(table)]
         result.append('SET')
         values, update_params = [], []
+
         for field, model, val in self.query.values:
+            if model and field.name not in model._state.update_fields:
+                continue
+
             if hasattr(val, 'prepare_database_save'):
                 val = val.prepare_database_save(field)
             else:

django/db/models/base.py

@@ -260 +260 @@
 
         signals.class_prepared.send(sender=cls)
 
+
 class ModelState(object):
     """
     A class for storing instance state
@@ -270 +271 @@
         # Necessary for correct validation of new instances of objects with explicit (non-auto) PKs.
         # This impacts validation only; it has no effect on the actual save.
         self.adding = True
+        self.update_fields = {}
 
+
 class Model(object):
     __metaclass__ = ModelBase
     _deferred = False
@@ -365 +368 @@
                     pass
             if kwargs:
                 raise TypeError("'%s' is an invalid keyword argument for this function" % kwargs.keys()[0])
+
         super(Model, self).__init__()
         signals.post_init.send(sender=self.__class__, instance=self)
 
+    def __setattr__(self, name, value):
+        is_for_update = False
+
+        if hasattr(self, name):
+            is_for_update = True
+
+        super(Model, self).__setattr__(name, value)
+        
+        if is_for_update:
+            local_fields = {x.name:x for x in self._meta.fields}
+            if name in local_fields:
+                self._state.update_fields.update({name:local_fields[name]})
+
     def __repr__(self):
         try:
             u = unicode(self)
@@ -524 +541 @@
                         manager.using(using).filter(pk=pk_val).exists())):
                     # It does already exist, so do an UPDATE.
                     if force_update or non_pks:
-                        values = [(f, None, (raw and getattr(self, f.attname) or f.pre_save(self, False))) for f in non_pks]
+                        values = [(f, self, (raw and getattr(self, f.attname) or f.pre_save(self, False))) for f in non_pks]
                         if values:
                             rows = manager.using(using).filter(pk=pk_val)._update(values)
                             if force_update and not rows: