request.object.previous() is not working in beforeSave()

Question

I'm trying to check the current and previous value of an attribute in the beforeSave(). So i tried to use request.object.previous("attribute_name") but it is still returning the current changed value. Although the .ditry() is returning TRUE which means that the value is changed. Any idea what is wrong here ? I appreciate your feedback.

Answer 1

I think the .previous() isn't actually part of the Parse.com sdk, but simply inherited from backbone.

In a beforeSave handler, I have something like:

if(object.dirty("attr")) { 
   console.log("After: " + object.get("attr") + ", Before: " + object.previous("attr")); }

The value returned by 'previous' is always the same. Is this functionality actually implemented? I've seen a few threads elsewhere that imply it's not - if so, can you remove it from the API docs until it's done?

If it doesn't work, is the correct workaround to query the previous object? Or does 'changedAttributes' work? Oh, I now see that 'previous' is some cruft from Backbone.

source1

previous is a method inherited from Backbone.Model. It won't return the previous value of a field in Cloud Code.

source2

Might not be the answer you're looking for, so as a way to workaround the lack of the .previous implementation this this out:

Don't know if this is helpful or if it would be considered too costly of a workaround, but you could add a column to the object that is being updated that stores the previous value of the original column. This would allow you to access the previous value in the AfterSave function.