Adds watch/unwatch functionality at forum topic level (#1912).

Users who create/reply a topic are automatically added as watchers but are now able to unwatch the topic.

git-svn-id: http://redmine.rubyforge.org/svn/trunk@1878 e93f8b46-1217-0410-a6f0-8f06a7374b81

db/migrate/098_set_topic_authors_as_watchers.rb

@@ -0,0 +1,14 @@
+class SetTopicAuthorsAsWatchers < ActiveRecord::Migration
+  def self.up
+    # Sets active users who created/replied a topic as watchers of the topic
+    # so that the new watch functionality at topic level doesn't affect notifications behaviour
+    Message.connection.execute("INSERT INTO watchers (watchable_type, watchable_id, user_id)" +
+                                 " SELECT DISTINCT 'Message', COALESCE(messages.parent_id, messages.id), messages.author_id FROM messages, users" +
+                                 " WHERE messages.author_id = users.id AND users.status = 1")
+  end
+
+  def self.down
+    # Removes all message watchers
+    Watcher.delete_all("watchable_type = 'Message'")
+  end
+end