[LRUG] Updating activerecord associations without saving

[Anthony Eden]

You could store the associated record as a simple instance variable on the
model.

Alternatively maybe the fact that someone is trying on the underwear before
buying it *is* something you want to keep track of, just through another
association?

Sincerely,
Anthony Eden

On Thu, Sep 23, 2010 at 3:34 PM, Tim Cowlishaw <tim at timcowlishaw.co.uk>wrote:

> Hi all,
>
> Could I pick your collective brains about a little activerecord issue I'm
> having?
>
> Let's say you have two AR models:
>
> class Person < ActiveRecord::Base
>        has_one :underpants
> end
>
> Underpants < ActiveRecord::Base
>        belongs_to :person
> end
>
> person = Person.create
> yfronts = Underpants.create
> boxers = Underpants.create
>
> person.underpants = boxers
> person.save
>
> Now, my app  allows people to test out underpants before they commit to
> them, so I want to set the underpants association on person, and keep the
> updated person in memory, without that change hitting the database until I
> explicitly save.
>
> But
> person.underpants = yfronts
>
> immediately updates the foreign key in the database. I can see why this
> happens - as the foreign key for the association is on my underpants table,
> it wouldn't be updated on hitting 'save' on the person, so it's done
> eagerly. However, is there any way to avoid this happening, and deal with
> the consequences myself?
>
> tl;dr: can I set a has_one association on an activerecord object in memory
> only, without touching the DB?
>
> Cheers.
>
> Tim
>
>
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