reduce the number of ActiveRecord objects generated when loading the …

…Asset editing form

app/models/contributor_role.rb

@@ -1,6 +1,7 @@
 class ContributorRole < ActiveRecord::Base
   include Picklist
   has_many :contributors
+  quick_column :name
 
   def safe_to_delete?
     contributors.size == 0

app/models/creator_role.rb

@@ -1,6 +1,7 @@
 class CreatorRole < ActiveRecord::Base
   include Picklist
   has_many :creators
+  quick_column :name
 
   def safe_to_delete?
     creators.size == 0

app/models/publisher_role.rb

@@ -1,6 +1,7 @@
 class PublisherRole < ActiveRecord::Base
   include Picklist
   has_many :publishers
+  quick_column :name
 
   def safe_to_delete?
     publishers.size == 0

app/models/subject.rb

@@ -1,6 +1,9 @@
 class Subject < ActiveRecord::Base
   include PbcoreXmlElement
+  include Picklist
+
   has_and_belongs_to_many :assets
+  quick_column 'CONCAT(subject, " (", subject_authority, ")")'
   xml_string "subject", :subject
   xml_string "subjectAuthorityUsed", :subject_authority
 

app/views/assets/_contributor.html.erb

@@ -1,9 +1,9 @@
 <div class="contributor">
   <p>
     <%= f.label(:contributor_role_id, "Contributor Role: ") %>
-    <%= f.select :contributor_role_id, ContributorRole.all(:conditions => ["visible = 1 OR id = ?", contributor.contributor_role_id]).map{|i| [i.name, i.id]} %>
+    <%= f.select :contributor_role_id, ContributorRole.quick_load_for_select(["visible = 1 OR id = ?", contributor.contributor_role_id]) %>
     &nbsp;&nbsp;
     <%= f.label(:contributor, "Contributor:") %> <%= f.text_field :contributor %>
     <%= f.remove_link "remove" %>
   </p>
-</div>
+</div>

app/views/assets/_creator.html.erb

@@ -1,9 +1,9 @@
 <div class="creator">
   <p>
     <%= f.label(:creator_role_id, "Creator Role: ") %>
-    <%= f.select :creator_role_id, CreatorRole.all(:conditions => ["visible = 1 OR id = ?", creator.creator_role_id]).map{|i| [i.name, i.id]} %>
+    <%= f.select :creator_role_id, CreatorRole.quick_load_for_select(["visible = 1 OR id = ?", creator.creator_role_id]) %>
     &nbsp;&nbsp;
     <%= f.label(:creator, "Creator:") %> <%= f.text_field :creator %>
     <%= f.remove_link "remove" %>
   </p>
-</div>
+</div>

app/views/assets/_publisher.html.erb

@@ -1,7 +1,7 @@
 <div class="publisher">
   <p>
     <%= f.label(:publisher_role_id, "Publisher Role: ") %>
-    <%= f.select :publisher_role_id, PublisherRole.all(:conditions => ["visible = 1 OR id = ?", publisher.publisher_role_id]).map{|i| [i.name, i.id]} %>
+    <%= f.select :publisher_role_id, PublisherRole.quick_load_for_select(["visible = 1 OR id = ?", publisher.publisher_role_id]) %>
     &nbsp;&nbsp;
     <%= f.label(:publisher, "Publisher:") %> <%= f.text_field :publisher %>
     <%= f.remove_link "remove" %>

app/views/assets/_subject.html.erb

@@ -1,10 +1,10 @@
 <div class="subject">
   <p>
     <select name="asset[subject_ids][]">
-      <%= options_for_select(Subject.all(:conditions => (subject.nil? ?
+      <%= options_for_select(Subject.quick_load_for_select(subject.nil? ?
             "visible = 1" : ["visible = 1 OR id = ?", subject.id]),
-            :order => "subject ASC").map{|s| ["#{s.subject} (#{s.subject_authority})", s.id]}, subject.id) %>
+            subject.id) %>
     </select>
     <%= f.remove_link "remove" %>
   </p>
-</div>
+</div>

lib/picklist.rb

@@ -1,4 +1,34 @@
 # A lot of PBCore fields are extensible picklists.
 module Picklist
 
+  module ClassMethods
+    # avoid instantiating lots and lots of ActiveRecord objects when
+    # all we need is a select box
+    def quick_load_for_select(conditions = nil)
+      sql = "SELECT #{get_quick_column} AS quick, id FROM #{connection.quote_table_name(table_name)}"
+      sanitized_conditions = sanitize_sql_for_conditions(conditions)
+      sql << " WHERE #{sanitized_conditions}" if sanitized_conditions
+      sql << " ORDER BY quick ASC"
+      result = connection.execute(sql)
+      rows = []
+      result.each{|row| rows << row}
+      result.free
+
+      rows
+    end
+
+    # set the column or other SQL expression which will be the title
+    # in quickly-loaded sqlect boxes
+    def quick_column(column)
+      write_inheritable_attribute("quick_column", column)
+    end
+
+    def get_quick_column #:nodoc:
+      read_inheritable_attribute("quick_column")
+    end
+  end
+
+  def self.included(base)
+    base.extend(ClassMethods)
+  end
 end