Make removal of topic columns more resilient to deploys

app/controllers/application_controller.rb

@@ -110,6 +110,32 @@ class ApplicationController < ActionController::Base
     end
   end
 
+  def self.last_ar_cache_reset
+    @last_ar_cache_reset
+  end
+
+  def self.last_ar_cache_reset=(val)
+    @last_ar_cache_reset
+  end
+
+  rescue_from ActiveRecord::StatementInvalid do |e|
+
+    last_cache_reset = ApplicationController.last_ar_cache_reset
+
+    if e.message =~ /UndefinedColumn/ && (last_cache_reset.nil?  || last_cache_reset < 30.seconds.ago)
+      Rails.logger.warn "Clear Active Record cache cause schema appears to have changed!"
+
+      ApplicationController.last_ar_cache_reset = Time.zone.now
+
+      ActiveRecord::Base.connection.query_cache.clear
+      (ActiveRecord::Base.connection.tables - %w[schema_migrations]).each do |table|
+        table.classify.constantize.reset_column_information rescue nil
+      end
+    end
+
+    raise e
+  end
+
   class PluginDisabled < StandardError; end
 
   # Handles requests for giant IDs that throw pg exceptions