As per readme of simple_form (https://github.com/plataformatec/simple_form),
the f.association helper is available with the collection option which
accepts the collection of objects that you want to provide for select list.
You can use :
f.association :driver, collection: Driver.unassociated, label_method: :name,
value_method: :id
# In Driver modelclass Driver < ActiveRecord::Base
scope :unlinked, -> { where(car_id: nil) }
end
*How to ensure validation before saving, to avoid problems of concurrent
accesses?*
For validation you can use uniqueness validation as :
class Driver < ActiveRecord::Base
validates_uniqueness_of :car_id
end
This way when any object of Driver is saved it will be checked that weather
the car_id was taken earlier or not and so the same car_id will not be
assigned to more than one driver.
Thanks,
Lauree
On Sunday, April 20, 2014 1:01:02 AM UTC+5:30, Ricardo do Valle wrote:
>
> I have two models (Car and Driver) and a combobox to select which driver
> belongs to which car. I want the combobox just show the objects that have
> not yet been associated.
>
> # vehicle belongs_to: driver
> # driver has_one: vehicle
> # simple_form # vehicle/_form.html.haml
> = f.association: driver, label_method: :name, value_method: :id
>
> How to ensure validation before saving, to avoid problems of concurrent
> accesses?
>
> Thanks
>
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