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   [2]gnikyt   /  Code ramblings
   [3]Ty King

   [4]About[5]Github[6]LinkedIn[7]CV[8]RSS

                  ActiveRecord and Liquid Drops with Sinatra /

   [9]Logo of ruby [10]Logo of sinatra

   Normally I use ERB when doing templates but there was a special
   use-case recently where I needed to allow the app user to modify a
   specific template. [11]Liquid templates (what Jekyll and Shopify use)
   was perfect for this situation because it has a simple syntax for
   anyone to pick up and it's also safe due to its scope limited to what's
   passed to the template.

   Let's suppose you have two models in your Sinatra application - Student
   and Book.
# app/models/student_model.rb
module MyApp
  module Model
    class Student
      has_many :books
    end
  end
end

# app/models/book_model.rb
module MyApp
  module Model
    class Book
      belongs_to :student
    end
  end
end

   Now, Liquid has what they call a [12]Drop, where you can easily build a
   plain class which Liquid can then use directly when rendering the
   template. As the [13]Drop Introduction states, it acts "like" a hash so
   the methods you create can be accessed with dot-notation in the
   template. Example: {% raw %}{{ student.full_name }}{% endraw %}

   So let's create a Student drop and a Book drop and give the templates
   some basic variables from the model to access.
# app/drops/student_drop.rb
module MyApp
  module Drop
    class Student
      def initialize(student)
        @student = student
      end

      def full_name
        "#{@student.first_name} {@student.last_name}"
      end

      def allergies
        @student.allergies.split ','
      end

      def books
        @student.books
      end
    end
  end
end

# app/drops/book_drop.rb
module MyApp
  module Drop
    class Book
      def initialize(book)
        @book = book
      end

      def title
        @book.title
      end

      def barcode
        @book.barcode
      end

      def date_printed
        @book.date_printed
      end
    end
  end
end

   Ok so now we have our models and drops setup. As you can see above
   we've set up methods for accessing the student's name, their books, the
   book title, barcode, etc. All of these methods can be used in a Liquid
   template now.

   But now, how do we easily combine the two? Easy, we utilize to_liquid
   method by adding it to our model which Liquid calls when rendering the
   template. We then return the proper drop for the model inside the new
   to_liquid method.
# app/models/student_model.rb
module MyApp
  module Model
    class Student
      has_many :books

      def to_liquid
        Drop::Student.new self
      end
    end
  end
end

# app/models/book_model.rb
module MyApp
  module Model
    class Book
      belongs_to :student

      def to_liquid
        Drop::Book.new self
      end
    end
  end
end

   That's pretty much it. We've now:
    1. Created our models
    2. Created our drops
    3. Modified our models to return a drop

   With all this combined we can then use it all together as such:
# app/controllers/front_controller.rb
...
student = Model::Student.find params[:id]
liquid :'front/test', layout: :layout_front, locals: {'student' => student}

{% raw %}
# app/views/front/test.liquid
My name is {{ student.full_name }}. I have {{ student.books.size }} books!
{% endraw %}

   That's it for this little how-to. I will note there are other ways to
   expose your ActiveRecord models to work automatically with Liquid but
   this article just shows you a more expanded and controlled version.

Anchors

     * [1] [14]http://liquidmarkup.org/ /^
     * [2] [15]github.com/Shopify/liquid/wiki/Introduction-to-Drops /^
     * [3] [16]github.com/Shopify/liquid/wiki/Introduction-to-Drops /^

Appendix

   This post is 10 years old and may contain outdated information.

   Copyright under [17]CC-4.0.

   Available in the following alternative formats:
   [18]MD  /  [19]TXT  /  [20]PDF

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References

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   2. file:///
   3. file:///about
   4. file:///about
   5. https://github.com/gnikyt
   6. https://linkedin.com/in/gnikyt
   7. file:///assets/files/cv.pdf
   8. file:///rss.xml
   9. file:///category/ruby
  10. file:///category/sinatra
  11. http://liquidmarkup.org/
  12. https://github.com/Shopify/liquid/wiki/Introduction-to-Drops
  13. https://github.com/Shopify/liquid/wiki/Introduction-to-Drops
  14. http://liquidmarkup.org/
  15. https://github.com/Shopify/liquid/wiki/Introduction-to-Drops
  16. https://github.com/Shopify/liquid/wiki/Introduction-to-Drops
  17. https://creativecommons.org/licenses/by/4.0/
  18. file:///activerecord-and-liquid-drops-with-sinatra/index.md
  19. file:///activerecord-and-liquid-drops-with-sinatra/index.txt
  20. file:///tmp/lynxXXXXH9xMW2/L13970-7650TMP.html