Speed up PublicBodyHelper#type_of_authority

Previously loaded all PublicBodyHeading and associated PublicBodyCategory
records. Now only loads the PublicBodyCategory records that relate to the
PublicBody.

          user     system      total        real
old   0.320000   0.000000   0.320000 (  0.356155)
new   0.010000   0.000000   0.010000 (  0.010077)

2 files changed, 11 insertions, 8 deletions

diff --git a/app/helpers/public_body_helper.rb b/app/helpers/public_body_helper.rb
index 54aa82d3a..e871ea1bc 100644
--- a/app/helpers/public_body_helper.rb
+++ b/app/helpers/public_body_helper.rb
@@ -40,15 +40,17 @@ module PublicBodyHelper
   # Returns a String
   def type_of_authority(public_body)
       first = true
-      types = public_body.tags.each.map do |tag|
-          if PublicBodyCategory.get.by_tag.include?(tag.name)
-              desc = PublicBodyCategory.get.singular_by_tag[tag.name]
-              if first
-                  desc = desc.sub(/\S/) { |m| Unicode.upcase(m) }
-                  first = false
-              end
-              link_to(desc, list_public_bodies_path(tag.name))
+
+      categories = PublicBodyCategory.
+                     where(:category_tag => public_body.tag_string.split)
+
+      types = categories.map do |category|
+          desc = category.description
+          if first
+              desc = desc.sub(/\S/) { |m| Unicode.upcase(m) }
+              first = false
           end
+          link_to(desc, list_public_bodies_path(category.category_tag))
       end
 
       types.compact!
diff --git a/spec/views/public_body/show.html.erb_spec.rb b/spec/views/public_body/show.html.erb_spec.rb
index a4edcfc22..c20d8483c 100644
--- a/spec/views/public_body/show.html.erb_spec.rb
+++ b/spec/views/public_body/show.html.erb_spec.rb
@@ -18,6 +18,7 @@ describe "public_body/show" do
         @pb.stub!(:special_not_requestable_reason?).and_return(false)
         @pb.stub!(:has_notes?).and_return(false)
         @pb.stub!(:has_tag?).and_return(false)
+        @pb.stub!(:tag_string).and_return('')
         @xap = mock(ActsAsXapian::Search, :matches_estimated => 2)
         @xap.stub!(:results).and_return([
           { :model => mock_event },