Hi Dave . . .
On May 29, 1:53 am, Davo [email protected] wrote:
an item has a brand and the brand has a number of models.
That sounds like this to me:
class Item < ActiveRecord::Base
has_many :brands
end
class Brand < ActiveRecord::Base
belongs_to :item
has_many :models
end
class Model < ActiveRecord::Base
belongs_to :brand
end
I see the migrations looking like this (I’ve cut out a lot of
boilerplate for brevity):
class CreateItems < ActiveRecord::Migration
// Nothing special needed
end
class CreateBrands < ActiveRecord::Migration
…
t.column :name, :string
t.column :item_id, :int
…
end
class CreateModels < ActiveRecord::Migration
…
t.column :name, :string
t.column :brand_id, :int
…
end
Also can someone point me in the right direction to do the model drop
down selection based on the previous selected brand ?
Sure. Take a look at the observe_field method we get with Rails +
Prototype:
http://api.rubyonrails.org/classes/ActionView/Helpers/PrototypeHelper.html#M000535
Don’t forget to put <% javascript_include_tag :defaults %> in your
form rhtml if you’re gonnna use observe_field. You basically want to
observe the drop-down for the brand, probably with a :frequency => 0
so that it fires whenever a new brand is selected. In your controller
you need an action that observe_field can call that returns the
contents of the model drop-down (which will be the value for
observe_field’s :update param). Use the :with param to assign a name
to the value that’s chosen in your brand drop-down (something
like :with => ‘chosen_brand’).
In your controller’s action, you’re going to do something along these
lines:
@models = Brand.find(params[:chosen_brand]).models
render :partial => ‘populate_model_select’
This assumes that your brands drop-down has been populated from the
DB, and the values of the options are the brand ID from the database
(check out collection_select in ActionView::Helpers::FormOptionsHelper
to accomplish that).
Then in your _populate_model_select.rhtml file, you’ll have something
like:
<% @models.each do |m| %>
<%= m.name %>
<% end %>
That oughtta get you started down the right path. 