Question

I’ve been playing around with the Liquid templating engine this weekend, and I wonder if the following is possible.

Say I have a latest_posts method in a Blog model, which I can pass an integer to to get the latest N posts. Is it possible to use that method in a liquid template?

For example:

class Blog

  has_many :posts

  def latest_posts(n)
    posts.latest(n) # using a named scope
  end

  def to_liquid(*args)
    {
      'all_posts' => posts.all,  # allows me to use {% for posts in blog.all_posts %}
      'last_post' => post.last,  # allows me to use {% assign recent = blog.last_post %}
      'latest_posts' => posts.latest_posts(args[0])  # how do I pass variables to this?
    }
  end

end

In the simplified example above, in my liquid templates I can use blog.all_posts and blog.last_post, but have no idea how I would do anything like blog.latest_posts: 10.

Can anyone point my in the right direction?

One idea I thought of was to create a Liquid filter and pass both the Blog object and an integer to that. Something like:

{% for post in blog | latest_posts(10) %}

• but haven’t tried that yet as feel like I’m stabbing around in the dark a bit. Would appreciate some help from more experienced Liquid users.

Answer 1

Answering my own question here, I found a solution documented in the Liquid groups pages.

Essentially, I needed to create a drop for the latest posts – a LatestPostsDrop – and kind of hack passing a variable to it using the before_method method. Here is the complete solution:

class Blog

  has_many :posts

  def latest_posts
    LatestPostsDrop.new(posts)
  end

  def to_liquid
    {
      'all_posts' => posts.all,
      'last_post' => post.last,
      'latest_posts' => latest_posts
    }
  end

end

class LatestPostsDrop < Liquid::Drop

  def initialize(posts)
    @posts = posts
  end

  def before_method(num)
    @posts.latest(num)    # Post.latest is a named scope
  end

end

Doing the above, allows you to iterate through any number of latest posts using something like:

{% for post in blog.latest_posts.10 %}  # the last attribute can be any integer
  <p>{{ post.title }}</p>
{% endfor %}

It seems a bit hacky, but it works 🙂