Question

I’m having trouble wrapping my head around this issue.

I have a business model and an address model. To make things more complicated, I also have a location model. A business can have multiple locations, but only one mailing address.

Here is a simple object chart.

Business
-Name
-MailingAddress

Location
-Business
-Name
-Address

I want to reuse the Address model for both the Businesses & Locations. What do I need to do for this. If it helps, I’m using MySQL.

First how to I structure the models? Do I need has_many :location,:business (for Location/Business)?
Then how do I nest the forms for creating addresses into new Business/Location forms.

Thanks!

Answer 1

I’ll start with some basic model code, then move onto controller, then views.

First the models:

#app/models/business.rb
class Business < ActiveRecord::Base
  has_one :mailing_address, :class_name => "Address", :dependent => :destroy
  accepts_nested_attributes_for :mailing_address

  has_many :locations
  accepts_nested_attributes_for :locations
end

#app/models/location.rb
class Location < ActiveRecord::Base
  has_one :address, :dependent => :destroy
  accepts_nested_attributes_for :address

  belongs_to :business
end

#app/models/address.rb
class Address < ActiveRecord::Base
  belongs_to :business
  belongs_to :location
end

Now the controller new action:

#app/controllers/businesses_controller.rb#new
def new
  @business = Business.new

  mailing_address = @business.build_mailing_address
  3.times do
    location = @business.locations.build
    address = location.build_address
  end
  respond_to do |format|
    format.html # new.html.erb
    format.xml  { render :xml => @business }
  end
end

Finally the views:

#app/views/businesses/_form.html.erb
<%= form_for(@business) do |f| %>
  <div class="field">
    <%= f.label :name %><br />
    <%= f.text_field :name %>
  </div>
  <%= f.fields_for :mailing_address do |builder| %>
    <h3>Mailing Address</h3>
    <%= render "address_fields", :f => builder %>
  <% end %>
  <%= f.fields_for :locations do |builder| %>
    <h3>Location</h3>
    <%= render "locations_fields", :f => builder %>
    <%= builder.fields_for :address do |mini_builder| %>
      <h3>Location Address</h3>
      <%= render "address_fields", :f => mini_builder %>
    <% end%>
  <% end %>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

address partial:

#app/views/businesses/_address_fields.html.erb
<p>
  <%= f.label "Street Address"%>
  <%= f.text_field :street %>
  <%= f.label "City"%>
  <%= f.text_field :city %>
  <%= f.label "State"%>
  <%= f.text_field :state %>
  <%= f.label "Zip"%>
  <%= f.text_field :zip %>  
</p>

location partial:

#app/views/businesses/_location_fields.html.erb
<p>
  <%= f.label "Location Name"%>
  <%= f.text_field :name%>
</p>

There are a couple trickier components in this whole thing. You have to keep in mind that building a has_one and a has_many child object is a different method in the controller. Also, you need to define the class properly for the mailing address relationship.

If you wanted populate the business mailing address from a collection of the locations associated with the businesses addresses, then you could add a method in the Business model that did something like this:

#app/models/business.rb#possible_mailing_addresses
def possible_mailing_addresses
  Location.where(:business_id=>self.id).joins(:address)
end