1 files changed, 21 insertions, 7 deletions
diff --git a/activerecord/lib/active_record/persistence.rb b/activerecord/lib/active_record/persistence.rb
index a1e1073792..466175690e 100644
--- a/activerecord/lib/active_record/persistence.rb
+++ b/activerecord/lib/active_record/persistence.rb
@@ -148,7 +148,7 @@ module ActiveRecord
     # Attributes marked as readonly are silently ignored if the record is
     # being updated.
     def save!(*args)
-      create_or_update(*args) || raise(RecordNotSaved.new(nil, self))
+      create_or_update(*args) || raise(RecordNotSaved.new("Failed to save the record", self))
     end
 
     # Deletes the record in the database and freezes this instance to
@@ -193,7 +193,7 @@ module ActiveRecord
     # and #destroy! raises ActiveRecord::RecordNotDestroyed.
     # See ActiveRecord::Callbacks for further details.
     def destroy!
-      destroy || raise(ActiveRecord::RecordNotDestroyed, self)
+      destroy || raise(RecordNotDestroyed.new("Failed to destroy the record", self))
     end
 
     # Returns an instance of the specified +klass+ with the attributes of the
@@ -205,7 +205,9 @@ module ActiveRecord
     # instance using the companies/company partial instead of clients/client.
     #
     # Note: The new instance will share a link to the same attributes as the original class.
-    # So any change to the attributes in either instance will affect the other.
+    # Therefore the sti column value will still be the same.
+    # Any change to the attributes on either instance will affect both instances.
+    # If you want to change the sti column as well, use +becomes!+ instead.
     def becomes(klass)
       became = klass.new
       became.instance_variable_set("@attributes", @attributes)
@@ -428,7 +430,7 @@ module ActiveRecord
       self
     end
 
-    # Saves the record with the updated_at/on attributes set to the current time 
+    # Saves the record with the updated_at/on attributes set to the current time
     # or the time specified.
     # Please note that no validation is performed and only the +after_touch+,
     # +after_commit+ and +after_rollback+ callbacks are executed.
@@ -477,11 +479,23 @@ module ActiveRecord
           changes[column] = write_attribute(column, time)
         end
 
-        changes[self.class.locking_column] = increment_lock if locking_enabled?
-
         clear_attribute_changes(changes.keys)
         primary_key = self.class.primary_key
-        self.class.unscoped.where(primary_key => self[primary_key]).update_all(changes) == 1
+        scope = self.class.unscoped.where(primary_key => _read_attribute(primary_key))
+
+        if locking_enabled?
+          locking_column = self.class.locking_column
+          scope = scope.where(locking_column => _read_attribute(locking_column))
+          changes[locking_column] = increment_lock
+        end
+
+        result = scope.update_all(changes) == 1
+
+        if !result && locking_enabled?
+          raise ActiveRecord::StaleObjectError.new(self, "touch")
+        end
+
+        result
       else
         true
       end