Move banner form partial to a component

Other than simplifying the controller, this'll make it easier to write
tests for this code.

app/components/admin/banners/form_component.html.erb

@@ -1,8 +1,8 @@
-<%= render "shared/globalize_locales", resource: @banner %>
+<%= render "shared/globalize_locales", resource: banner %>
 
-<%= translatable_form_for [:admin, @banner] do |f| %>
+<%= translatable_form_for [:admin, banner] do |f| %>
 
-  <%= render "shared/errors", resource: @banner %>
+  <%= render "shared/errors", resource: banner %>
 
   <div class="row">
     <div class="small-12 medium-3 column">
@@ -36,7 +36,7 @@
   <div class="row">
     <fieldset class="small-12 column">
       <legend><%= t("admin.banners.banner.sections_label") %></legend>
-      <%= f.collection_check_boxes(:web_section_ids, @banner_sections, :id, :name) do |b| %>
+      <%= f.collection_check_boxes(:web_section_ids, sections, :id, :name) do |b| %>
         <%= b.label do %>
           <%= b.check_box + t("admin.banners.banner.sections.#{b.text}") %>
         <% end %>
@@ -79,6 +79,6 @@
   </div>
 
   <div class="row">
-    <%= render Shared::BannerComponent.new(@banner) %>
+    <%= render Shared::BannerComponent.new(banner) %>
   </div>
 <% end %>

app/components/admin/banners/form_component.rb

@@ -0,0 +1,15 @@
+class Admin::Banners::FormComponent < ApplicationComponent
+  include TranslatableFormHelper
+  include GlobalizeHelper
+  attr_reader :banner
+
+  def initialize(banner)
+    @banner = banner
+  end
+
+  private
+
+    def sections
+      WebSection.all
+    end
+end

app/controllers/admin/banners_controller.rb

@@ -3,8 +3,6 @@ class Admin::BannersController < Admin::BaseController
 
   has_filters %w[all with_active with_inactive], only: :index
 
-  before_action :banner_sections, only: [:edit, :new, :create, :update]
-
   respond_to :html, :js
 
   load_and_authorize_resource
@@ -47,10 +45,6 @@ class Admin::BannersController < Admin::BaseController
        web_section_ids: []]
     end
 
-    def banner_sections
-      @banner_sections = WebSection.all
-    end
-
     def resource
       @banner ||= Banner.find(params[:id])
     end

app/views/admin/banners/edit.html.erb

@@ -5,6 +5,6 @@
 
     <h1><%= t("admin.banners.edit.editing") %></h1>
 
-    <%= render "form" %>
+    <%= render Admin::Banners::FormComponent.new(@banner) %>
   </div>
 </div>

app/views/admin/banners/new.html.erb

@@ -5,6 +5,6 @@
 
     <h1><%= t("admin.banners.new.creating") %></h1>
 
-    <%= render "form" %>
+    <%= render Admin::Banners::FormComponent.new(@banner) %>
   </div>
 </div>