Middleman Categories

This is an extension to make it easy to categorize Middleman pages with front matter. Methods are exposed that provide for linking to generated pages that can provide a list of links to all pages in a category.

The key use case is for porting a blog from WordPress that defines both tags and categories. WordPress says that tags should enumerate content details for a page, and categories should describe larger buckets for content.

To use

1. In your Gemfile, add the gem:

    gem 'middleman-categories', git: 'https://github.com/jgn/middleman-categories.git'
   

2. In your config.rb, activate the extension:

    activate :categories
   

3. To any page that you want to categorize, add front matter with a categories line. If you want a page to be in multiple buckets, separate the category names with a space. Example:

    ---
    categories: Reading, Reviews, Management
    ---
   

4. In your config.rb: If you want pages to be generated listing links for each category, call proxy_categories in the ready block:

    ready do
      proxy_categories
    end
   

5. Create a page called category.html.erb. Here you will add markup that lists links for all pages within a category. It might look something like this:

    Page in the category "<%= category_name %>"
   
    <ul>
      <% pages_by_category[category_name].each_with_index do |page, i| %>
        <li><%= link_to page.data.title, page %> <span>(<%= page.data.date %>)</span></li>
      <% end %>
    </ul>
   

   category_name is injected into this template by the extension. The extension exposes pages_by_category, which acts like a hash, to give you access to an array of pages for each category name.

   Note: If you are using the Middleman Blog extension, and you know that the page in question is a blog article, you might use the Middleman Blog helpers to get at the title and date, for instance . . .

    <ul>
      <% pages_by_category[category_name].each_with_index do |page, i| %>
        <li><%= link_to page.title, page %> <span>(<%= page.date.strftime('%B %e, %Y') %>)</span></li>
      <% end %>
    </ul>
   

6. You can also list the categories defined in the front matter for a page. For example:

    ---
    title: Demo of categories
    date: 2018-03-03 16:15 +0000
    categories: Reading, Reviews, Management
    tags:
    ---
   
    ## Categories demo
   
    Hello!
   
    This page is in the categories
    <% categories_for_page(current_page).each do |category| %>
      <%= link_to category, category_path(category) %>
    <% end %>
   

Exposed methods and variables

And just to be clear about methods exposed by the extension: proxy_categories is exposed to config.rb so that pages can be dynamically generated for each category.

The following three methods are exposed to a template:

method or variable	explanation
categories_for_page(page)	Returns an Enumerable of Strings representing the category names
pages_by_category	Returns a Hash-like object with an Enumerable of Middleman pages for each key which is a String representing a category name (so you can write pages_by_category["Reading"])
category_path(category)	Returns a path to the page describing the category
category_name	Not a method, but a variable injected into the category.html proxy