Truncate Markdown

Truncate Markdown?

• Write/find an intelligent HTML truncating function

The following from http://mikeburnscoder.wordpress.com/2006/11/11/truncating-html-in-ruby/, with some modifications will correctly truncate HTML, and easily allow appending a string before the closing tags.

>> puts "<p><b><a href=\"hi\">Something</a></p>".truncate_html(5, at_end = "...")
=> <p><b><a href="hi">Someth...</a></b></p>

The modified code:

require 'rexml/parsers/pullparser'

class String
  def truncate_html(len = 30, at_end = nil)
    p = REXML::Parsers::PullParser.new(self)
    tags = []
    new_len = len
    results = ''
    while p.has_next? && new_len > 0
      p_e = p.pull
      case p_e.event_type
      when :start_element
        tags.push p_e[0]
        results << "<#{tags.last}#{attrs_to_s(p_e[1])}>"
      when :end_element
        results << "</#{tags.pop}>"
      when :text
        results << p_e[0][0..new_len]
        new_len -= p_e[0].length
      else
        results << "<!-- #{p_e.inspect} -->"
      end
    end
    if at_end
      results << "..."
    end
    tags.reverse.each do |tag|
      results << "</#{tag}>"
    end
    results
  end

  private

  def attrs_to_s(attrs)
    if attrs.empty?
      ''
    else
      ' ' + attrs.to_a.map { |attr| %{#{attr[0]}="#{attr[1]}"} }.join(' ')
    end
  end
end

How do i truncate a post (HTML/Markdown) but not give invalid markup

In case of HTML it's been answered before.

In case of Markdown, you could convert whole Markdown text to HTML, and see previous point. Otherwise you'd have to write Markdown parser (state machine) that parses source up to a certain point, keeping track of all open constructs, and then closes all of them.

Is there a markdown friendly alternative to truncatechars:x ?

You can use the truncatechars_html tag.

{{ post.text | custom_markdown | truncatechars_html:160 }}

Combining truncate with Redcarpet markdown in Rails: Links don't work

That link isn't Markdown though, it's HTML. Maybe change it to Markdown?

<%= markdown(truncate(post.content, length: 600,
                      separator: ' ', omission: '... ') {
             "[read more](#{post_path(post)})"
    }) %>

Change post_path to something appropriate if that's not right.

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