Question

I have two models

class Car
    has_many :engines                         
end

class Engine
    belongs_to :car
end

In the car form I have a select field where the user can select the engine type. The list might be “1.4L; 1.6L; 2.0L…”

Lets say I want to display additional information from the Engine model when the user selects a engine. This should be displayed on the Car form. This might be e.g. BHP, max revs, …etc

How do I set something like this up. I guess there are two aspects:

1. How to display data from the engine
   model on the car form without using
   a field (this data is not editable).

2. How to update this data dynamically
   when the user selects an option in
   the select field.

Can anyone point me towards a starting point for this. I’m a bit lost where to begin.

Many thanks!

Answer 1

If you’re working with collection_select in your form, you are setting two arguments, like :id and :name in your collection_select call. :id is the method called to determine the value for the option tag and :name is the method used to display the option tag’s content.

Solution: Create a method (e.g. :name_for_select) in your engine model which returns a string with more information about your engine and call collection_select with :id, :name_for_select instead.