Using liquid to sort posts alphabetically

Question

Is there a way to sort a number of posts alphabetically, using Jekyll?

I have something like this now:

{% for post in site.categories.threat %}


        

Answer 1

I adapted a Jekyll plugin from https://gist.github.com/3812259 to accomplish this. I couldn't use the plugin as-is, because it failed in the presence of null values. I'm a beginning ruby programmer, and coded the null handling with help from https://stackoverflow.com/a/808721/1135052

sort_for example reversing the sort and performing case-sensitive string comparisons (ignored if the sorted property is not a string):

{% sorted_for node in site.pages reversed sort_by:title case_sensitive:true %}
  {{ node.title }}
{% endsorted_for %}

sorted_keys_for example:

{% sorted_keys_for tag in site.tags %}
  {{ tag }}

  Num posts: {{ site.tags[tag].size }}
{% endsorted_keys_for %}

For use in Jekyll, put this code in _plugins/sort_for.rb

module Jekyll
  module SortedForImpl
    def render(context)
      sorted_collection = collection_to_sort context
      return if sorted_collection.empty?
      sort_attr = @attributes['sort_by']
      case_sensitive = @attributes['case_sensitive'] == 'true'
      i = sorted_collection.first

      if sort_attr != nil
        if i.to_liquid[sort_attr].instance_of? String and not case_sensitive
          sorted_collection.sort_by! { |i|
            k = i.to_liquid[sort_attr]
            k ? k.downcase : ''
          }
        else
          sorted_collection.sort_by! { |i|
            k = i.to_liquid[sort_attr]
            [k ? 1 : 0,k || 1]
          }
        end
      else
        if i.instance_of? String and not case_sensitive
          sorted_collection.sort_by! { |i| i.downcase }
        else
          sorted_collection.sort!
        end
      end

      original_name = @collection_name
      result = nil
      context.stack do
        sorted_collection_name = "#{@collection_name}_sorted".sub('.', '_')
        context[sorted_collection_name] = sorted_collection
        @collection_name = sorted_collection_name
        result = super
        @collection_name = original_name
      end
      result
    end
  end

  class SortedForTag < Liquid::For
    include SortedForImpl

    def collection_to_sort(context)
      return context[@collection_name].dup
    end

    def end_tag
      'endsorted_for'
    end
  end

  class SortedKeysForTag < Liquid::For
    include SortedForImpl

    def collection_to_sort(context)
      return context[@collection_name].keys
    end

    def end_tag
      'endsorted_keys_for'
    end
  end
end

Liquid::Template.register_tag('sorted_for', Jekyll::SortedForTag)
Liquid::Template.register_tag('sorted_keys_for', Jekyll::SortedKeysForTag)