Add tag search[has_wiki] parameter

fixes #1870

app/models/tag.rb

@@ -575,6 +575,12 @@ class Tag < ActiveRecord::Base
         q = q.where("post_count > 0")
       end
 
+      if params[:has_wiki] == "yes"
+        q = q.joins(:wiki_page)
+      elsif params[:has_wiki] == "no"
+        q = q.joins("LEFT JOIN wiki_pages ON tags.name = wiki_pages.title").where("wiki_pages.title IS NULL")
+      end
+
       params[:order] ||= params.delete(:sort)
       case params[:order]
       when "name"

app/views/tags/_search.html.erb

@@ -38,6 +38,15 @@
         </td>
       </tr>
 
+      <tr>
+        <th><label for="search_has_wiki">Has a Wiki Page</label></th>
+        <td>
+          <div class="input">
+            <%= select "search", "has_wiki", ["yes", "no"], :selected => params[:search][:has_wiki], :include_blank => true %>
+          </div>
+        </td>
+      </tr>
+
       <tr>
         <td><%= submit_tag "Search" %><td>
       </tr>