Allow FieldConfigs to change shuffle algorithm.

Author: bamnet

app/controllers/frontend/contents_controller.rb

@@ -4,6 +4,8 @@ class Frontend::ContentsController < ApplicationController
   before_filter :scope_setup
   before_filter :screen_api
 
+  DEFAULT_SHUFFLE = 'WeightedShuffle'
+
   def scope_setup
     @screen = Screen.find(params[:screen_id])
     @field = Field.find(params[:field_id])
@@ -12,7 +14,8 @@ def scope_setup
 
   def index
     require 'frontend_content_order'
-    shuffler_klass = FrontendContentOrder.load_shuffler('WeightedShuffle')
+    shuffle_config = FieldConfig.get(@screen, @field, 'shuffler') || DEFAULT_SHUFFLE
+    shuffler_klass = FrontendContentOrder.load_shuffler(shuffle_config)
     session_key = "frontend_#{@screen.id}_#{@field.id}".to_sym
     shuffler = shuffler_klass.new(@screen, @field, @subscriptions, session[session_key])
     @content = shuffler.next_contents()

app/models/field_config.rb

@@ -7,34 +7,13 @@ class FieldConfig < ActiveRecord::Base
   validates_presence_of :key, :field_id, :screen_id
   validates_uniqueness_of :key, :scope => [:screen_id, :field_id]
 
-  # Enable hash-like access to table for ease of use
-  # Shortcut for self.get(key)
-  def self.[](key)
-    self.get(key.to_s)
-  end
-  
-  # Make setting values from Rails nice and easy
-  def self.set(key,value)
-    #only set this if the config already exists
-    setting = FieldConfig.where(:key => key).first
-    setting.update_column(:value, value)
-  end  
-
-  # Make getting values from Rails nice and easy
-  # Returns false if key isn't found or the config is broken.
-  def self.get(key)
-    setting = FieldConfig.where(:key => key).first
-      if setting.nil?
-        raise "Field config key #{key} not found!"
-      end    
-    return setting.value
-  end
-  
-  # Creates a Field Config entry by taking the key and value desired
-  def self.make_field_config(field_id, config_key,config_value)
-    # first_or_create: check whether first returns nil or not; if it does return nil, create is called
-    FieldConfig.where(:key => config_key).first_or_create(:field_id => field_id, :key => config_key, :value => config_value)
-  end  
-    
+  def self.get(screen, field, key)
+    field_config = FieldConfig.where(:screen_id => screen.id, :field_id => field.id, :key => key).first
+    if !field_config.nil?
+      return field_config.value
+    else
+      return nil
+    end
+  end    
 end
 

lib/frontend_content_order.rb

@@ -9,7 +9,12 @@ module FrontendContentOrder
   #    Defaults to a BaseShuffle algorithm.
   # @return [Class] Shuffle algorithm class.
   def self.load_shuffler(shuffler_name='BaseShuffle')
-    require shuffler_name.underscore unless defined? shuffler_name.constantize
-    return shuffler_name.constantize
+    begin
+      require shuffler_name.underscore unless defined? shuffler_name.constantize
+      return shuffler_name.constantize
+    rescue
+      Rails.logger.error("Trouble loading shuffler: #{shuffler_name}.")
+      return BaseShuffle
+    end
   end
 end

test/fixtures/field_configs.yml

@@ -4,8 +4,12 @@
 # model remove the '{}' from the fixture names and add the columns immediately
 # below each fixture, per the syntax in the comments below
 #
-one: {}
-# column: value
-#
+one:
+  screen: one
+  field: one
+  key: keyname
+  value: valuehere
+
+
 two: {}
 #  column: value

test/unit/field_config_test.rb

@@ -23,4 +23,9 @@ class FieldConfigTest < ActiveSupport::TestCase
     dup.screen = screens(:two)
     assert dup.valid?
   end
+
+  test "fieldconfig get" do
+    assert FieldConfig.get(screens(:one), fields(:one), 'missing').nil?
+    assert_equal 'valuehere', FieldConfig.get(screens(:one), fields(:one), 'keyname')
+  end
 end