Rails grouped_collection_select with 3 models

Question

I'm attempting to follow the Rails Docs and Railscast#88 but with 3 models. The page will have 3 drop down boxes for State, County, & City. I have State > County working with JQuery. But when trying to build the grouped_collecion_select for the City things are breaking down.

Here are the 3 models:

service_area_state.rb

 class ServiceAreaState < ActiveRecord::Base
    has_many :service_area_counties
    default_scope -> { order(name: :asc) }
 end

service_area_county.rb

class ServiceAreaCounty < ActiveRecord::Base
    belongs_to :service_area_state
    default_scope -> { order(name: :asc) }
end

service_area_city.rb

class ServiceAreaCity < ActiveRecord::Base
    belongs_to :service_area_county
end

In my controller, I have the following:

def index

    @states = ServiceAreaState.all
    @counties = ServiceAreaCounty.all
    @cities = ServiceAreaCity.all

end #index

In the view I have:

index.html.erb

<div class="row">
<div class="field" id='state_div'>

    <%= label_tag :service_area_state_id, "State", id:"service_area_state" %> <br/>

**This works**
    <%= collection_select(:service_area_state, :id, @states, :id, :name, prompt: true ) %>

</div>

<div class="field" id='county_div'>
    <%= label_tag :service_area_county_id, "County" %><br>

**This works**
    <%= grouped_collection_select(:service_area_county, :service_area_county_id, @states, :service_area_counties, :name, :id, :name, prompt: true ) %>
</div>

<div class="field" id='city_div'>
    <%= label_tag :service_area_city_id, "City" %><br>

**This does not work**
    <%= grouped_collection_select(:service_area_city, :service_area_county_id, @counties, :service_area_cities, :name, :id, :name, prompt: true )   %>
</div>
</div>

I get the following error:

undefined method `service_area_cities' for #<ServiceAreaCounty:0x007fb5e7dac060>

On this line:

<%= grouped_collection_select(:service_area_city, :service_area_county_id, @counties, :service_area_cities, :name, :id, :name, prompt: true )   %>

Can someone spot where I went wrong?

Thanks!

Answer 1

You need to set up service_area_cities as an association in the ServiceAreaCounty model (sounds like it is a has_many association):

class ServiceAreaCounty < ActiveRecord::Base
  belongs_to :service_area_state
  has_many :service_area_cities
  default_scope -> { order(name: :asc) }
end