Module: Nanoc2::Helpers::Blogging

Defined in:
lib/nanoc2/helpers/blogging.rb

Overview

Nanoc2::Helpers::Blogging provides some functionality for building blogs, such as finding articles and constructing feeds.

This helper has a few requirements. First, all blog articles should have the following attributes:

  • ‘kind’, set to ‘article’.

  • ‘created_at’, set to the creation timestamp.

Some functions in this blogging helper, such as the atom_feed function, require additional attributes to be set; these attributes are described in the documentation for these functions.

The two main functions are sorted_articles and atom_feed.

To activate this helper, include it, like this:

include Nanoc2::Helpers::Blogging

Instance Method Summary collapse

Instance Method Details

#articles ⇒ Object

Returns an unsorted list of articles.



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# File 'lib/nanoc2/helpers/blogging.rb', line 25

def articles
  @pages.select { |page| page.kind == 'article' }
end

#atom_feed(params = {}) ⇒ Object

Returns a string representing the atom feed containing recent articles, sorted by descending creation date. params is a hash where the following keys can be set:

limit

The maximum number of articles to show. Defaults to 5.

articles

A list of articles to include in the feed. Defaults to the list of articles returned by the articles function.

content_proc

A proc that returns the content of the given article, passed as a parameter. By default, given the argument article, this proc will return article.content. This function may not return nil.

excerpt_proc

A proc that returns the excerpt of the given article, passed as a parameter. By default, given the argument article, this proc will return article.excerpt. This function may return nil.

The following attributes must be set on blog articles:

  • ‘title’, containing the title of the blog post.

  • all other attributes mentioned above.

The following attributes can optionally be set on blog articles to change the behaviour of the Atom feed:

  • ‘excerpt’, containing an excerpt of the article, usually only a few lines long.

  • ‘custom_path_in_feed’, containing the path that will be used instead of the normal path in the feed. This can be useful when including non-outputted pages in a feed; such pages could have their custom feed path set to the blog path instead, for example.

The feed will also include dates on which the articles were updated. These are generated automatically; the way this happens depends on the used data source (the filesystem data source checks the file mtimes, for instance).

The feed page will need to have the following attributes:

  • ‘base_url’, containing the URL to the site, without trailing slash. For example, if the site is at “example.com/”, the base_url would be “example.com”. It is probably a good idea to define this in the page defaults, i.e. the ‘meta.yaml’ file (at least if the filesystem data source is being used, which is probably the case).

  • ‘title’, containing the title of the feed, which is usually also the title of the blog.

  • ‘author_name’, containing the name of the page’s author. This will likely be a global attribute, unless the site is managed by several people/

  • ‘author_uri’, containing the URI for the page’s author, such as the author’s web site URL. This will also likely be a global attribute.

The feed page can have the following optional attributes:

  • ‘feed_url’, containing the custom URL of the feed. This can be useful when the private feed URL shouldn’t be exposed; for example, when using FeedBurner this would be set to the public FeedBurner URL.

To construct a feed, create a blank page with no layout, only the ‘erb’ (or ‘erubis’) filter, and an ‘xml’ extension. It may also be useful to set ‘is_hidden’ to true, so that helpers such as the sitemap helper will ignore the page. The content of the feed page should be:

<%= atom_feed %>



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# File 'lib/nanoc2/helpers/blogging.rb', line 106

def atom_feed(params={})
  require 'builder'

  # Extract parameters
  limit             = params[:limit] || 5
  relevant_articles = params[:articles] || articles || []
  content_proc      = params[:content_proc] || lambda { |a| a.content }
  excerpt_proc      = params[:excerpt_proc] || lambda { |a| a.excerpt }

  # Check feed page attributes
  if @page.base_url.nil?
    raise RuntimeError.new('Cannot build Atom feed: feed page has no base_url')
  end
  if @page.title.nil?
    raise RuntimeError.new('Cannot build Atom feed: feed page has no title')
  end
  if @page.author_name.nil?
    raise RuntimeError.new('Cannot build Atom feed: feed page has no author_name')
  end
  if @page.author_uri.nil?
    raise RuntimeError.new('Cannot build Atom feed: feed page has no author_uri')
  end

  # Check article attributes
  if relevant_articles.empty?
    raise RuntimeError.new('Cannot build Atom feed: no articles')
  end
  if relevant_articles.any? { |a| a.created_at.nil? }
    raise RuntimeError.new('Cannot build Atom feed: one or more articles lack created_at')
  end

  # Get sorted relevant articles
  sorted_relevant_articles = relevant_articles.sort_by { |a| a.created_at }.reverse.first(limit)

  # Get most recent article
  last_article = sorted_relevant_articles.first

  # Create builder
  buffer = ''
  xml = Builder::XmlMarkup.new(:target => buffer, :indent => 2)

  # Build feed
  xml.instruct!
  xml.feed(:xmlns => 'http://www.w3.org/2005/Atom') do
    # Add primary attributes
    xml.id      @page.base_url + '/'
    xml.title   @page.title

    # Add date
    xml.updated last_article.created_at.to_iso8601_time

    # Add links
    xml.link(:rel => 'alternate', :href => @page.base_url)
    xml.link(:rel => 'self',      :href => feed_url)

    # Add author information
    xml.author do
      xml.name  @page.author_name
      xml.uri   @page.author_uri
    end

    # Add articles
    sorted_relevant_articles.each do |a|
      xml.entry do
        # Add primary attributes
        xml.id        atom_tag_for(a)
        xml.title     a.title, :type => 'html'

        # Add dates
        xml.published a.created_at.to_iso8601_time
        xml.updated   a.mtime.to_iso8601_time

        # Add link
        xml.link(:rel => 'alternate', :href => url_for(a))

        # Add content
        summary = excerpt_proc.call(a)
        xml.content   content_proc.call(a), :type => 'html'
        xml.summary   summary, :type => 'html' unless summary.nil?
      end
    end
  end

  buffer
end

#atom_tag_for(page) ⇒ Object

Returns an URI containing an unique ID for the given page. This will be used in the Atom feed to uniquely identify articles. These IDs are created using a procedure suggested by Mark Pilgrim in this blog post: diveintomark.org/archives/2004/05/28/howto-atom-id.



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# File 'lib/nanoc2/helpers/blogging.rb', line 208

def atom_tag_for(page)
  hostname        = @page.base_url.sub(/.*:\/\/(.+?)\/?$/, '\1')
  formatted_date  = page.created_at.to_iso8601_date

  'tag:' + hostname + ',' + formatted_date + ':' + page.path
end

#feed_url ⇒ Object

Returns the URL of the feed. It will return the custom feed URL if set, or otherwise the normal feed URL.



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# File 'lib/nanoc2/helpers/blogging.rb', line 200

def feed_url
  @page[:feed_url] || @page.base_url + @page.path
end

#sorted_articles ⇒ Object

Returns a list of articles, sorted by descending creation date (so newer articles appear first).



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# File 'lib/nanoc2/helpers/blogging.rb', line 31

def sorted_articles
  articles.sort_by { |a| a.created_at }.reverse
end

#url_for(page) ⇒ Object

Returns the URL for the given page. It will return the URL containing the custom path in the feed if possible, otherwise the normal path.



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# File 'lib/nanoc2/helpers/blogging.rb', line 194

def url_for(page)
  @page.base_url + (page.custom_path_in_feed || page.path)
end