jekyll-category-pages

jekyll-category-pages

This plugin adds category index pages with and without pagination.
Benefits are:

• Easy to setup and use, fully compatible with the default pagination plugin (also cf. the official documentation).
• Supports category keys with spaces and other special characters.
• Complete documentation and a usage example.
• Test coverage of key features.
• Category index pages are generated based on a customizable template.

Usage

Assign one or more categories in the YAML front matter of each page:

categories: [Category Pages Plugin, jekyll]

Generate the site and the category pages are generated:

_site/category/
├── category-pages-plugin/
│   └── index.html
├── 好的主意/
│   └── index.html
└── jekyll/
    ├── index.html
    ├── page2.html
    └── page3.html

In this example there are three paginated index pages for the jekyll category (apparently, there are many posts for this category), a single index page for the 好的主意 category and another single index page for the Category Pages Plugin category.

Note that the YAML categories entry should always use brackets [] to make it explicit that it is an array!

You can find this example in the example directory of the git repository.

The example project

The example directory contains a basic example project that demonstrates the different use cases. In order to run Jekyll on these examples use:

bundle install
bundle exec rake example

The result is put in example/_site.

Installation and setup

Installation is straightforward (like other plugins):

1. Add the plugin to the site's Gemfile and configuration file and also install the jekyll-paginate gem (the latter is a required dependency even if you don't use it):

   group :jekyll_plugins do
     gem "jekyll-paginate"
     gem "jekyll-category-pages"
   end
   

2. Add the plugin to your site's _config.yml:

   plugins:
     - jekyll-category-pages
   

3. This step is optional, but recommended: Also add this line to _config.yml which excludes categories from file URLs (they are ugly and don't work properly in Jekyll, anyways):

   permalink: /:year/:month/:day/:title:output_ext
   

4. Configure any other options you need (see below).
5. Add template for category pages (see below).
6. Set appropriate categories tags on each blog post YAML front matter.

Configuration

The following options can be set in the Jekyll configuration file _config.yml:

• category_path: Root directory for category index pages. Defaults to category if unset.
  In the example this places the index file for category jekyll at example/_site/category/jekyll/index.html.
• category_layout: Basic category index template. Defaults to category_index.html. The layout must reside in the standard _layouts directory.
  In the example the layout is in example/_layouts/category_index.html.
• paginate: (Maximum) number of posts on each category index page. This is the same for the regular (front page) pagination. If absent, pagination is turned off and only single index pages are generated.
  In the example paginate is set to 2.

Template for category pages

The template for a category index page must be placed in the site's _layouts directory. The attribute category indicates the current category for which the page is generated. The page title also defaults to the current category. The other attributes are similar to the default Jekyll pagination plugin.

If no pagination is enabled the following attributes are available:

Attribute	Description
category	Current page category
posts	List of posts in current category
total_posts	Total number of posts in current category

If pagination is enabled (i.e., if setting site.paginate globally in _config.yml) then a paginator attribute is available which returns an object with the following attributes:

Attribute	Description
page	Current page number
per_page	Number of posts per page
posts	List of posts on the current page
total_posts	Total number of posts in current category
total_pages	Total number of pagination pages for the current category
previous_page	Page number of the previous pagination page, or nil if no previous page exists
previous_page_path	Path of previous pagination page, or '' if no previous page exists
next_page	Page number of the next pagination page, or nil if no subsequent page exists
next_page_path	Path of next pagination page, or '' if no subsequent page exists

An example can be found in example/_layouts/category_index.html which demonstrates the various attributes and their use.

Category listing

A category overview with a full listing of all categories can be created as follows:

<ul>
{% for category in site.categories %}
<li><a href="{{ site.url }}/category/{{ category | first | slugify }}/index.html">{{ category | first }}</a></li>
{% endfor %}
</ul>

Note that the category page paths are URL-encoded when generated by this plugin. Thus, you have to use slugify when linking to each category. This saves you from problems with spaces or other special characters in category names.

An example listing can be found in example/index.html which shows a full listing of categories with corresponding links.

Categories on a single page

Listing the categories in a single page is particularly simple since the categories listed in the YAML front matter are directly available as strings in page.categories. However, unlike the site-wide category list in site.categories the content of page.categories are just strings and can thus be added as follows (with references):

<ul>
{% for category in page.categories %}
<li><a href="{{ site.url }}/path-to-category-index/{{ category | slugify }}/index.html">{{ category }}</a></li>
{% endfor %}
</ul>

Development

This project contains a Rakefile that supports the following tasks:

• build: Runs all tests and builds the resulting gem file.
• test: Run all tests.
• example: Run Jekyll for the example project.
• clean: Clean up all transient files.

To run all test cases use:

bundle exec rake test

The tests run different Jekyll configurations and produce output files that can be read by Ruby. These are then evaluted and validated using Ruby RSpec.

To build the gem use:

bundle exec rake build

The result is put in the current directory after all tests have been run.

Gotchas

The following issues and limitations are known:

• Jekyll currently does not properly escape special HTML entities (like & or <) in permalink paths. Because of that you cannot use them in category names. If you still want to use them you need to adjust the permalink path as shown above -- it must not contain category names.

License

The gem is available as open source under the terms of the MIT License.