configurable album thumbnails

app/controllers/photos.rb

@@ -88,4 +88,19 @@ class Photos < Application
   end
   alias_method :thumbnail, :send_rmagicked_image
   alias_method :screen, :send_rmagicked_image
+  
+  def set_album_thumbnail
+    only_provides :html
+    @photo = Photo.find(params[:id])
+    raise NotFound unless @photo
+    @album = @photo.album
+    raise NotFound unless @album
+    if @album.update_attribute(:album_thumbnail_id, @photo.id)
+      flash[:notice] = 'Very nice!'
+    else
+      flash[:error] = 'Could not update the album:<br />'
+      @album.errors.each_full { |msg| flash[:error] += "#{msg}<br />" }
+    end
+    redirect url(:photo, @photo)
+  end
 end

app/models/album.rb

@@ -5,6 +5,7 @@ class Album < ActiveRecord::Base
   has_and_belongs_to_many :tags, :order => 'tags.name ASC'
   has_many :photos
   after_create :save_tags
+  belongs_to :album_thumbnail, :class_name => 'Photo'
   
   def tag_names
     self.tags.collect { |t| t.name }.join(' ')
@@ -22,10 +23,6 @@ class Album < ActiveRecord::Base
     self.tags = new_tags
   end
   
-  def album_thumbnail
-    self.photos.first
-  end
-  
   def self.for_select
     self.find(:all, :select => 'name', :order => 'name ASC').collect do |a|
       a.name

app/views/photos/show.html.erb

@@ -229,6 +229,7 @@ function toggle_photo_tag_editor(direction)
 
 <% throw_content :for_sidebar do -%>
   <a href="<%= url(:album, :id => @photo.album.name.gsub(/ /, '_')) -%>"><img src="/images/camera-photo.png" /> Back to <%= @photo.album.name -%></a><br />
+  <% if allowed_to?(:edit_album, @photo.album) and @photo.album.album_thumbnail_id != @photo.id -%><a href="<%= url(:action => :set_album_thumbnail, :id => @photo.id) -%>" rel="nofollow"><img src="/images/emblem-photos.png" /> Make album thumbnail</a><br /><% end -%>
   <% if allowed_to?(:edit_photo, @photo) and @photo.exist? -%><a href="<%= url(:edit_photo, :id => @photo.id) -%>" rel="nofollow"><img src="/images/document-save.png" /> Edit photo</a><br /><% end %>
   <% if allowed_to?(:delete_photo, @photo) -%><a href="<%= url(:delete_photo, :id => @photo.id) -%>" onclick="if(!confirm('Are you sure you want to delete this photo?')){return false;}" rel="nofollow"><img src="/images/edit-delete.png" /> Destroy photo</a><br /><% end -%>
   <% if @photo.exist? -%><a href="<%= photo_url(@photo) -%>"><img src="/images/image-x-generic.png" /> Download original</a><br /><% end -%>

config/router.rb

@@ -34,6 +34,10 @@ Merb::Router.prepare do |r|
     :controller => 'photos',
     :action => 'screen'
   )
+  r.match('/photos/set_album_thumbnail/:id').to(
+    :controller => 'photos',
+    :action => 'set_album_thumbnail'
+  )
   r.resources :photo_tags
   r.match('/').to(
     :controller => 'news',

schema/migrations/012_album_thumbnail_migration.rb

@@ -0,0 +1,13 @@
+class AlbumThumbnailMigration < ActiveRecord::Migration
+  def self.up
+    add_column :albums, :album_thumbnail_id, :integer
+    add_index :albums, :album_thumbnail_id
+    Album.find(:all).each do |album|
+      album.update_attribute :album_thumbnail_id, (album.photos.first.id rescue nil)
+    end
+  end
+
+  def self.down
+    remove_column :albums, :album_thumbnail_id
+  end
+end

schema/schema.rb

@@ -9,13 +9,15 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 11) do
+ActiveRecord::Schema.define(:version => 12) do
 
   create_table "albums", :force => true do |t|
-    t.string "name", :limit => 128
+    t.string  "name",               :limit => 128
+    t.integer "album_thumbnail_id", :limit => 11
   end
 
   add_index "albums", ["name"], :name => "index_albums_on_name"
+  add_index "albums", ["album_thumbnail_id"], :name => "index_albums_on_album_thumbnail_id"
 
   create_table "albums_tags", :id => false, :force => true do |t|
     t.integer "album_id", :limit => 11
@@ -112,6 +114,10 @@ ActiveRecord::Schema.define(:version => 11) do
   add_index "photos", ["author_id"], :name => "index_photos_on_author_id"
   add_index "photos", ["album_id"], :name => "index_photos_on_album_id"
 
+  create_table "schema_info", :id => false, :force => true do |t|
+    t.integer "version", :limit => 11
+  end
+
   create_table "sessions", :force => true do |t|
     t.string   "session_id"
     t.text     "data"