Record when a post was hidden

app/models/post_action.rb

@@ -307,7 +307,7 @@ class PostAction < ActiveRecord::Base
       reason = guess_hide_reason(old_flags)
     end
 
-    Post.where(id: post.id).update_all(["hidden = true, hidden_reason_id = COALESCE(hidden_reason_id, ?)", reason])
+    Post.where(id: post.id).update_all(["hidden = true, hidden_at = CURRENT_TIMESTAMP, hidden_reason_id = COALESCE(hidden_reason_id, ?)", reason])
     Topic.where(["id = :topic_id AND NOT EXISTS(SELECT 1 FROM POSTS WHERE topic_id = :topic_id AND NOT hidden)",
                       topic_id: post.topic_id]).update_all({ visible: false })
 

db/migrate/20140620184031_add_hidden_at_to_posts.rb

@@ -0,0 +1,5 @@
+class AddHiddenAtToPosts < ActiveRecord::Migration
+  def change
+    add_column :posts, :hidden_at, :timestamp
+  end
+end

lib/post_revisor.rb

@@ -100,6 +100,7 @@ class PostRevisor
     if @editor == @post.user && @post.hidden && @post.hidden_reason_id == Post.hidden_reasons[:flag_threshold_reached]
       @post.hidden = false
       @post.hidden_reason_id = nil
+      @post.hidden_at = nil
       @post.topic.update_attributes(visible: true)
 
       PostAction.clear_flags!(@post, -1)

spec/models/post_action_spec.rb

@@ -98,14 +98,17 @@ describe PostAction do
       admin = Fabricate(:admin)
       PostAction.act(codinghorror, post, PostActionType.types[:off_topic])
       post.hidden.should be_false
+      post.hidden_at.should be_blank
       PostAction.defer_flags!(post, admin.id)
       PostAction.flagged_posts_count.should == 0
       post.reload
       post.hidden.should be_false
+      post.hidden_at.should be_blank
 
       PostAction.hide_post!(post, PostActionType.types[:off_topic])
       post.reload
       post.hidden.should be_true
+      post.hidden_at.should be_present
     end
 
   end
@@ -253,6 +256,7 @@ describe PostAction do
 
       post.hidden.should.should be_true
       post.hidden_reason_id.should == Post.hidden_reasons[:flag_threshold_reached]
+      post.hidden_at.should be_present
       post.topic.visible.should be_false
 
       post.revise(post.user, post.raw + " ha I edited it ")
@@ -260,6 +264,7 @@ describe PostAction do
 
       post.hidden.should be_false
       post.hidden_reason_id.should be_nil
+      post.hidden_at.should be_blank
       post.topic.visible.should be_true
 
       PostAction.act(u1, post, PostActionType.types[:spam])
@@ -269,12 +274,14 @@ describe PostAction do
 
       post.hidden.should be_true
       post.hidden_reason_id.should == Post.hidden_reasons[:flag_threshold_reached_again]
+      post.hidden_at.should be_true
 
       post.revise(post.user, post.raw + " ha I edited it again ")
 
       post.reload
 
       post.hidden.should be_true
+      post.hidden_at.should be_true
       post.hidden_reason_id.should == Post.hidden_reasons[:flag_threshold_reached_again]
     end