Helper for using YAML Frontmatter in partials for Middleman. This expects HAML and a specific structuring and naming of partials (/source/partials/components/_COMPONENTNAME.html.haml) although it could be updated pretty easily. The goal behind this is to serve snippets of components (e.g. a "cta" snippet). This partial file would include frontma…

_default.html.haml

// Example of the partial for cta shown above
---
cta_class: default
cta_text: My Text!
cta_href: '#'
---

%a{:class => "#{cta_class}", :href => "#{cta_href"}"} #{cta_text}

including-in-layout.html.haml

// Include with just default data
= snippet "cta/_default"

// Overriding default data is easy
= snippet "cta/_default", {:cta_text => 'Click this yo', :cta_href => '/path/to/file.html'}

yaml-partial-helper.rb

helpers do
  def snippet(component, overrides = nil)

    def colorize(text, color_code)
      "\e[#{color_code}m#{text}\e[0m"
    end

    def red(text); colorize(text, 31); end
    def green(text); colorize(text, 32); end


    basepath = File.expand_path File.dirname(__FILE__)
    exists = File.exists?(basepath << "/source/partials/components/" << component << ".html.haml")

    if exists
      # Read the partial, get the YAML, extend that hash with any overrides passed in
      yaml_regex = /\A(---\s*\n.*?\n?)^(---\s*$\n?)/m
      content = File.read(basepath)
      content = content.sub(yaml_regex, "")
      data = YAML.load($1)

      # Extend the hash so that any overrides are used instead of the defaults
      if overrides != nil
        overrides.each_key do |key|
          data[key] = overrides[key]
        end
      end
    else
      puts red('[ERROR:]') + " Partial #{component} not found!"
      return '<span style="color: red; font-weight: bold;">Error: Partial \'' + component + '\' not found!</span>'
    end

    ##
    # At this point, we have our data and know it exists
    # Just load that partial baby
    ##
    partial "/partials/components/" << component.sub("_", ""), :locals => data

  end
end

Nice work. However, for some reason the reg expression provided doesn't seem to work with the newest version of MiddleMan.

To get it fixed, use this one yaml_regex = /---(.*[\s\S]*)---/m