ToJ

ToJ is a helpful gem that allows you to build json from your active model object or collection. ToJ allows you to define a Serializer with many methods called views. A view is a method that describe how to generate json. So if you want to generate a json with only the author data you can use author.to_j, but if you want add also the books you can use author.to_j(view: :with_books).

Installation

Add this line to your application's Gemfile:

gem 'to_j'

And then execute:

$ bundle

Or install it yourself as:

$ gem install to_j

Usage

In your models include the ToJ module:

class Author < ApplicationRecord
  include ToJ
  has_many :books, dependent: :destroy
end

class Book < ApplicationRecord
  include ToJ
  belongs_to :author

  def nice_title
    self.title.titleize
  end
end

Then in the app/serializers directory create a serializer for each model:

# app/serializers/author_serializer.rb
module AuthorSerializer

  def default(author, options = {})
    self.extract!(author, :id, :name)
    if options[:user]&.admin?
      self.extract!(author, :email)
    end
  end

  def with_books(author, options = {})
    default(author, options)
    self.books do
      self.array!(author.books.map { |book| book.to_j(options) })
    end
  end

end

# app/serializers/book_serializer.rb
module BookSerializer

  def default(book, options = {})
    self.extract!(book, :id, :title, :nice_title)
  end

  def only_title(book, options = {})
    self.extract!(book, :title)
  end

end

The default view is called if the option :view is not present on to_j options param.

Now you can call:

Author.limit(100).to_j
# [{"id"=>1028680, "name"=>"Kristopher", {...}, ...]
Author.limit(100).to_j(view: :with_books)
# [{"id"=>1028680, "name"=>"Kristopher", "books"=>[{"id"=>192756823, "title"=>"If not now, when?", "nice_title"=>"If Not Now, When?"}, {...}, ...]
Book.first.to_j(view: :only_title)
# {"title"=>"Jesting pilate"}

or in your controllers:

def index
  @authors = Author.limit(100)
  respond_to do |format|
    format.html
    format.json { render json: @authors.to_j(user: current_user) }
  end
end

def show
  @author = Author.find(params[:id])
  respond_to do |format|
    format.html
    format.json { render json: @author.to_j(view: :with_books) }
  end
end

If a serializer or default method is not defined all table columns will be added in the json (default Rails behavior).

Under the hood there is Jbuilder

The self object in serializer's methods are a Jbuilder object so you can use the Jbuilder DSL to create and personalized your json views.

Performance

In the test directory I've write a simple benchmark to check the performance of this gem with other common serializers:

Here the results to build a json of 10_000 authors with a total of 100_000 books:

Run options: --seed 333

# Running:

         user        system    total     real
to_j      9.950000   0.340000  10.290000 ( 10.367328)
as_json  15.460000   0.400000  15.860000 ( 15.942882)
ams      16.000000   0.460000  16.460000 ( 16.578348)
jbuilder  9.940000   0.380000  10.320000 ( 10.305331)

License

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

to_j

Development

Runtime

ToJ

Installation

Usage

Under the hood there is Jbuilder

Performance

License