Rails Polymorphic Associations has_one / belongs_to

Question

I have the following situation:

I have a model called "ConfigurationItem".

class ConfigurationItem < ActiveRecord::Base

  belongs_to :contract_asset
  belongs_to :provider

  belongs_to :configuration, polymorphic: true


  validate :name, :contract_asset, presence: true

end

Then I have for the moment two models, "OsConfiguration" and "HardwareConfiguration"

class OsConfiguration < ActiveRecord::Base

  has_one :configuration_item, as: :configuration

end

class HardwareConfiguration < ActiveRecord::Base

  has_one :configuration_item, as: :configuration

end

On my process of creation, I first come to the form of ConfigurationItem. So my question is, how can I create an Os or Hardware Configuration from the ConfigurationItem form. Something like this:

What I tried so far is to route like this:

resources :configuration_items do
    resources :os_configurations
    resources :hardware_configurations
end

But the rest is a bit heavy for me (I'm very new to rails).

Plus, I'm using this gem : https://github.com/codez/dry_crud

edit:

To be more specific, from the configurationItem a form, I can choose an os or hardware configuration. If I choose an os configuration, a modal form will appear with his form. When I save the Os Configuration, I have to set his attribute configuration_item with the previous form, so he's not created yet and I can't access it from the os configuration's controller.

It's like in rails_admin when from a form, you can create and add a new instance of an other model.

Thank's !

Answer 1

Here is my solution, In my ConfigurationItem's list view, I added the dropdown menu

%ul.dropdown-menu.pull-right
      - ConfigurationItemsController::ITEM_TYPES.keys.each do |type|
        %li= link_to("Add #{type.titleize} Item", new_contract_contract_asset_configuration_item_path(@contract, @contract_asset, type: type))

In my ConfigurationItemsController, I create the configuration with the type of the dropdown.

ITEM_TYPES = { 'plain'    => nil,
                 'os'       => OsConfiguration,
                 'hardware' => HardwareConfiguration }

before_filter :assign_configuration_type, only: [:new, :create]

def assign_configuration_type
    if type = ITEM_TYPES[params[:type]]
      entry.configuration = type.new
    end
end

def models_label(plural = true)
    if @configuration_item
      if config = @configuration_item.configuration
        "#{config.class.model_name.human.titleize} Item"
      else
        "Plain Configuration Item"
      end
    else
      super(plural)
    end
end

In my ConfigurationItem's form view I extend the form with my configuration's field

- if entry.new_record?
    = hidden_field_tag :type, params[:type]

- if @configuration_item.configuration
    = f.fields_for(:configuration) do |fields|
      = render "#{@configuration_item.configuration.class.model_name.plural}/fields", f: fields

So I choose before the form which configuration I'll have, and not in the form.

Answer 2

In the configuration_items_controller where you create the object, check the selection from the dropdown input and depending on what it is set to create that object instead.

def create
 item = ConfigurationItem.new
 ... do what you need to here ...
 item.save
 if (params[:dropdown]=='OS Configuration')
   os_config = OSConfiguration.new
   ... do what you need to ...
   os_config.configuration_id = item.id
   os_config.save
 elseif (params[:dropdown]=='Hardware Configuration')
   hardware_config = HardwareConfiguration.new
   ... do what you need to ...
   hardware_config.configuration_id = item.id
   hardware_config.save
 end
end