Question

My Post model has the following columns:

t.datetime "published_at"
t.string   "status"

published_at Should only be defined once (the first time the post.status equals "Published"):

post.rb:

 before_save :publish_post

 protected

    def publish_post
      if self.status == "Published" && self.published_at.nil?
       self.published_at = Time.now
      end
    end

Now, I added a posts_count column to the Tag model:

t.integer  "posts_count", :default => 0, :null => false

The counter should only increment and decrement if the post.status equals "Published" (Shouldn’t increment is post.status equals "Draft"):

taggings.rb:

  after_save    :increment_tag_counter_cache
  after_destroy :decrement_tag_counter_cache

  private

   def increment_tag_counter_cache
     if self.post.status == "Published" && self.post.published_at.nil?
       Tag.increment_counter(:posts_count, self.tag.id)
     end
   end

   def decrement_tag_counter_cache
      if self.post.status == "Published" && self.post.published_at.nil?
        Tag.decrement_counter(:posts_count, self.tag.id)
      end
    end

For some reason, the right now the counter is not being incremented or decremented. I tried removing code and discovered that the problem is this part: self.post.published_at.nil?.

I’m not very sure what’s going on. I’m pretty sure published_at is nil at that moment. What could be the problem?

Answer 1

How do you know that

post.status == "Published" && post.published_at is really nil?

?

post.published_at can be just blank. like “”

post.published_at.blank?

Examples of .blank? and .nil?:

"".nil?
#=> false

nil.nil?
#=> true

nil.blank?
#=> true

"".blank?
#=> true

"  ".blank?
#=> true

"     ".blank?
#=> true   

[].blank?
#=> true

{}.blank?
#=> true