Automatically delete oldest post of a specified tag

You really need to delete the post? With :limit => 20 in your find is
not enought?. If the answer is a double yes, then you should use an
ActiveRecord callback (perhaps after_save
http://api.rubyonrails.org/classes/ActiveRecord/Callbacks.html#M002084)

Regards.

Franco Catena.

The callback would be placed in the post model correct? And that
callback would include code that would find the amount of posts in that
tag if it exists? Then how would I use that in the post controller's
create method? Sorry I'm still trying to grasp MVC :frowning:

The callback would be placed in the post model correct?

Yes.

And that callback would include code that would find the
amount of posts in that tag if it exists?

Yes.

Then how would I use that in the post controller's create
method?

When you call @post.save in the controller the appropiated callbacks
in the Post model are called, so you don't need a explicit call to a
function or do another thing inside the model.

Regards.

Franco Catena.

Thank you Franco for being so helpful and understanding. I appreciate
it.

Hello, I'm trying to create that callback method. Here's what I have so
far.
post model:

class Post < ActiveRecord::Base
  after_create :check_posts_per_tag
  after_create :destroy_oldest_post_of_tag
  acts_as_taggable #<-- for acts_as_taggable_on_steroids
  validates_presence_of :body, :title, :tag_list
  has_many :comments

  #...

  def destroy_oldest_post_of_tag
    self.class.first.destroy
  end

  protected #<-- should this be protected?
  def check_posts_per_tag
    @inputtag = :tag_list #<-- will this grab the input from the form?
    @postspertag = post.tag_counts # maybe post.tag.count?
    if @inputtag.exists? then
      if @postspertag >= 20 then
        # delete the oldest post of that tag needs to happen here
        post.destroy_oldest_post_of_tag
      end
    end
  end
end

Does this look pretty close to what I described above? I'm trying to
understand whats going on here. The comments in the code include some of
my questions. I'm not sure if that's how I grab the input from the form,
and I'm also not sure if that's how I would delete the oldest post of
the given tag either...

Anyone?