[LRUG] Updating activerecord associations without saving

[Tim Cowlishaw]

On 23 Sep 2010, at 14:43, Anthony Green wrote:

> 
> I usually use build in similar circumstances
> 
> Person.build_underpants(:type => 'boxers')
> 

Ok, this is exactly what I thought, but even using build, it's updating the foreign key on the underpants table (nulling it out) when i instaantiate the new underpants instance. It's absolutely madenning!

Chers,

Tim




> 
> 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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