[LRUG] Updating activerecord associations without saving

[Anthony Green]

I usually use build in similar circumstances

Person.build_underpants(:type => 'boxers')


On 23/09/2010 14:34, "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

-- 
Anthony Green






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