Rails 4: collection_check_box error

Question

I am building a form that launches a new Campaign. With this Campaign, you can choose a Zip file and/or some PDF files. Zip and PDF files are all stored in an Uploads table.

So far, it appears I can choose a Zip file, however, once I add the collection_check_box for PDFs, create a Campaign, I receive the following error...

expected Array (got String) for param `upload_ids'

My form looks like this..

<%= form_for @campaign, url: {action: "create"} do |f| %>
   <%= f.label :name, class: "right-label" %>
   <%= f.text_field :name %>

   <%= f.label :comment, "Comments" %>
   <%= f.text_area :comment %>


   <%= f.label :zip_file, class: "right-label" %>

   <%= f.collection_select :upload_ids, Upload.where(file_type: ".zip"), :id, :file_name, include_blank: "Include a Zip File" do |b| %>
        <%= b.option + File.basename(b.text, '.*') %>
    <% end %>

   <%= f.label :pdf_files %>

<ul><%= f.collection_check_boxes :upload_ids, Upload.where(file_type: ".pdf"), :id, :file_name do |b| %>
    <li><%= b.label do %>
        <%= b.check_box + File.basename(b.text,'.*') %>
    </li>
        <% end %>
    <% end %>
</ul>

Here is a the error displayed on the server as requested.

[2015-06-01 14:50:57] ERROR Rack::Utils::ParameterTypeError: expected Array (got String) for param `upload_ids'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/rack-1.6.1/lib/rack/utils.rb:142:in `normalize_params'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/rack-1.6.1/lib/rack/utils.rb:156:in `normalize_params'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/rack-1.6.1/lib/rack/utils.rb:117:in `block in parse_nested_query'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/rack-1.6.1/lib/rack/utils.rb:114:in `each'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/rack-1.6.1/lib/rack/utils.rb:114:in `parse_nested_query'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/rack-1.6.1/lib/rack/request.rb:369:in `parse_query'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/rack-1.6.1/lib/rack/request.rb:215:in `POST'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/rack-1.6.1/lib/rack/methodoverride.rb:39:in `method_override_param'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/rack-1.6.1/lib/rack/methodoverride.rb:27:in `method_override'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/rack-1.6.1/lib/rack/methodoverride.rb:15:in `call'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/rack-1.6.1/lib/rack/runtime.rb:18:in `call'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/activesupport-4.2.1/lib/active_support/cache/strategy/local_cache_middleware.rb:28:in `call'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/rack-1.6.1/lib/rack/lock.rb:17:in `call'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/actionpack-4.2.1/lib/action_dispatch/middleware/static.rb:113:in `call'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/rack-1.6.1/lib/rack/sendfile.rb:113:in `call'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/railties-4.2.1/lib/rails/engine.rb:518:in `call'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/railties-4.2.1/lib/rails/application.rb:164:in `call'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/rack-1.6.1/lib/rack/lock.rb:17:in `call'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/rack-1.6.1/lib/rack/content_length.rb:15:in `call'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/gems/2.2.0/gems/rack-1.6.1/lib/rack/handler/webrick.rb:89:in `service'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/2.2.0/webrick/httpserver.rb:138:in `service'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/2.2.0/webrick/httpserver.rb:94:in `run'
    /Users/Josh/.rbenv/versions/2.2.2/lib/ruby/2.2.0/webrick/server.rb:294:in `block in start_thread'

EDIT

If I delete one of the collection blocks (zip or pdf), my Campaign creation is successful.

It appears as if there is a conflict with my "upload_ids" on both the Zip file and PDF file selection methods above. Even though my model relationship states that a Campaign has_many: uploads, through: uploadable and has_many: uploadable, it's trying to accept both - the Zip and PDF/s - one instance of upload_id.

I'm still unsure how to get around this. Any help is appreciated.

controllers/campaigns_controller.rb

class CampaignsController < ApplicationController
      def index
        @campaigns = Campaign.all.order("created_at DESC")
      end

      def new
        @campaign = Campaign.new
      end

      def create
        @campaign = Campaign.new(campaign_params)

        if @campaign.save
            flash[:success] = "Campaign Successfully Launched!"
            redirect_to @campaign
        else
            flash[:error] = "There was a problem launching your Campaign."
            redirect_to new_campaign_path
        end
      end

      def show
        @campaign = Campaign.find(params[:id])
      end

  private

      def campaign_params
        params.require(:campaign).permit(:name, :comment)
      end
end

log/development.log

Started GET "/campaigns/new" for ::1 at 2015-06-01 18:54:19 -0700
Processing by CampaignsController#new as HTML
  [1m[35mUpload Load (0.2ms)[0m  SELECT "uploads".* FROM "uploads"
  [1m[36mUpload Load (0.3ms)[0m  [1mSELECT "uploads".* FROM "uploads" WHERE "uploads"."file_type" = $1[0m  [["file_type", ".zip"]]
  [1m[35mUpload Load (0.1ms)[0m  SELECT "uploads".* FROM "uploads" WHERE "uploads"."file_type" = $1  [["file_type", ".pdf"]]
  Rendered campaigns/_form.html.erb (6.6ms)
  Rendered campaigns/new.html.erb within layouts/application (7.5ms)
  Rendered layouts/_header.html.erb (0.2ms)
  Rendered layouts/_footer.html.erb (0.0ms)
Completed 200 OK in 82ms (Views: 80.4ms | ActiveRecord: 0.5ms)

Update #1

Another Developer friend noted that I cannot use "upload_ids" for both collection_selects. That is also apparent in my experiments above. So how do I allow a user to associate the object with 2 other objects from a separate model/table?

I changed one collection_select object param to be uploadable_ids but that is a random name I placed. I have no clue what to put as that parameter. Now I receive the flash[:error] "There was a problem launching your Campaign."

Update #2

I've tried many suggestions including the ones on this posting but still struggling to get this to work. The select_tag throws and undefined method so for the time being, I'm simply using select. I tried adding the upload_ids[] yet was thrown an error that there needed to be more arguments.

I'm also confused on whether I need to add anything to my controller. Will my Active Record associations be enough when I decide to query which Campaign is associated with which files?

Here is the zip and pdf portion of the form in its current state..

<%= f.label :data_file, class: "right-label" %>

<%= f.select :upload_ids, 
    options_from_collection_for_select(
    Upload.where(file_type: ".zip"), :id, :file_name), 
    {include_blank: "Include a Zip File"}, {mulitple: true} %>

<%= f.label :additional_files %>

<%= f.collection_check_boxes(:upload_ids, 
    Upload.where(file_type: ".pdf"), :id, :file_name, 
    { mulitple: true }) do |b| %>
            <%= b.label do %>
              <%= b.check_box + File.basename(b.text,'.*') %>
            <% end %>
<% end %>

If it is of any added help, here the model relationships:

class Campaign < ActiveRecord::Base
  has_many  has_many :uploadable
  has_many :uploads, through: :uploadable
end

class Uploadable < ActiveRecord::Base
  belongs_to :campaign
  belongs_to :upload
end

class Upload < ActiveRecord::Base
  has_many :uploadable
  has_many :campaigns, through: :uploadable
end

Answer 1

The main issue I see is that your checkboxes are submitting an array parameter (you can select multiple check boxes) but your collection_select is trying to submit a singular value. The mixing of the two is what causes the Rack::Utils::ParameterTypeError

Your uploads association is a has_many so using an array parameter is the right thing to do. The simplest possible thing you can do is make the select a multiple choice one, by adding the multiple: true option. Note that this must go in a separate hash to your include_blank option.

To keep a separate select I think you'll need to drop down to calling select_tag and specify upload_ids[] as the input name. You can still use options_from_collection_for_select to generate the option tags.