Question

The case is simple: I have markdown in my database, and want it parsed on output(*).

@post.body is mapped to the posts.body column in the database. Simple, default Activerecord ORM. That column stores the markdown text a user inserts.

Now, I see four ways to offer the markdown rendered version to my views:

First, in app/models/post.rb:

# ...
def body
   markdown = RDiscount.new(body)
   markdown.to_html
end

Allowing me to simply call @post.body and get an already rendered version. I do see lots of potential problems with that, e.g. on edit the textfield being pre-filled with the rendered HMTL instead of the markdown code.

Second option would be a new attribute in the form of a method

In app/models/post.rb:

# ...
def body_mardownified
   markdown = RDiscount.new(body)
   markdown.to_html
end

Seems cleanest to me.

Or, third in a helper in app/helpers/application_helper.rb

def markdownify(string)
   markdown = RDiscount.new(string)
   markdown.to_html
end

Which is used in the view, instead of <%= body %>, <%= mardownify(body) %>.

The fourth way, would be to parse this in the PostsController.

def index
  @posts = Post.find(:all)
  @posts.each do |p|
    p.body = RDiscount.new(string).to_html
    @rendered_posts << p
  end
end

I am not too familiar with Rails 3 proper method and attribute architecture. How should I go with this? Is there a fifth option? Should I be aware of gotchas, pitfalls or performance issues with one or another of these options?

(*) In future, potentially updated with a database caching layer, or even special columns for rendered versions. But that is beyond the point, merely pointing out, so to avoid discussion on filter-on-output versus filter-on-input :).

Answer 1

Yet another way would be extending the String class with a to_markdown method. This has the benefit of working on any string anywhere in your application

class String
  def to_markdown
    RDiscount.new(self)
  end
end

@post.body.to_markdown

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