Dealing with nil in views (ie nil author in @post.author.name)

Question

I want to show a post author's name; <% @post.author.name %> works unless author is nil. So I either use unless @post.author.nil? or add a author_name method that checks for nil as in <% @post.author_name %>. The latter I try to avoid.

The problem is that I may need to add/remove words depending on whether there is a value or not. For instance, "Posted on 1/2/3 by " would be the content if I simply display nil. I need to remove the " by " if author is nil.

Answer 1

Null object pattern is one way to avoid this. In your class:

def author
  super || build_author
end

This way you will get an empty author no matter what. However, since you don't actually want to have an empty object sometimes when you do expect nil, you can use presenter of some kind.

class PostPresenter
  def initialize(post)
    @post = post
  end

  def post_author
    (@post.author && @post.author.name) || 'Anonymous'
  end
end

Another way is using try, as in @post.author.try(:name), if you can get used to that.