Math with core data

[jollyrgr]

I have a core data app the has an entity named "house" with float type attributes labeled "arv" and "offer".

I want to subtract "offer" from "arv", how do I do this? Can I do it in core data or can I do it in a class?

Thanks in advance and the best of the holidays to your families!


Roger

[sneaky]

Core Data, and any database for that matter, will only hold data for you. For any type of calculation you must retrieve the data and perform the calculation yourself.

[Duncan C]

Originally Posted by jollyrgr

I have a core data app the has an entity named "house" with float type attributes labeled "arv" and "offer".

I want to subtract "offer" from "arv", how do I do this? Can I do it in core data or can I do it in a class?

Thanks in advance and the best of the holidays to your families!


Roger

It depends on the details.

It sounds like you want to be able to calculate the value of offer-arv for every instance of your house entity.

In that case you should create a derived property of your house entity.

You typically create an object for your entity that is a subclass of NSManagedObject. You can add properties to your subclass (or a category of your NSManagedObject class) that let you fetch calculated values. In your case, you could add a new readonly property calculatedValue who's getter would return offer-arv.