Dynamic Content

Sometimes you may find useful to generate content dynamically. Maybe you’re going to read some configuration file, or maybe you just want to define some helpers. Kitabu has support for ERb files; all you need to do is naming your text file as .erb.

On the previous chapter, we listed all supported Rouge lexers. To do that, I created a helper that looks like this:

module Kitabu
  module Helpers
    def lexers_list
      buffer = '<ul class="lexers">'

      Rouge::Lexers.constants.each do |const|
        lexer = Rouge::Lexers.const_get(const)

        begin
          title = lexer.title
          tag = lexer.tag
          description = lexer.desc
        rescue Exception => e
          next
        end

        buffer << '<li>'
        buffer << "<strong>#{title}</strong> "
        buffer << "<code>#{tag}</code><br>"
        buffer << "<span>#{description}</span>"
        buffer << '</li>'
      end

      buffer << '</ul>'
      buffer
    end
  end
end

To use it, I just needed to add <%= lexers_list %> to my text file. This allows you to create anything you need!

Kitabu comes with some built-in helpers, such as note. With this helper, you can create a note that generates a HTML structure, so you can easily style it. The syntax for using the note helper is note(type, &block).

<% note do %>
  Some text that will be parsed as Markdown.
<% end %>

By default, this will generate a <div class="note info"> tag, but you can use anything you want.

<% note :warning do %>
  Some text that will be parsed as Markdown.
<% end %>

Check out the source for a sample on how to create block helpers like note.

Escaping ERb code

If you want to write a book about Rails, you’re likely to use lots of ERb tags. In this case, make sure you escape the and markers as <% %> and <%= %>; otherwise you’ll have a syntax error.

<%%= Date.today %>