Hb

Simple Hash Builder which has ActiveModelSerializers like interface.

Installation

Add this line to your application's Gemfile:

gem 'hb'

And then execute:

$ bundle

Or install it yourself as:

$ gem install hb

Usage

Creating Presenter

Subclass Hb::Base and declare attributes.

class PersonPresenter < Hb::Base
  attributes :id, :email
  attribute :last_name, key: :family_name
end

The attributes names are whitelist of attributes to be exposed. You can change key name by using :key option.

Building Hash

Person = Struct.new(:id, :email, :last_name, :first_name, :age)

person = Person.new(1, 'shozawa@sample.com', 'shozawa', 'tomohiro', 28)

PersonPresenter.new(person).to_h

# => { id: 1, email: 'shozawa@sample.com', family_name: 'shozawa' }

# you can pass ActiveModel object like this
PersonPresenter.new(User.find(1)).to_h

# and you can use factory method
PersonPresenter.wrap(person)

Building Collection

people = [
  Person.new(1, 'nobunaga', 'oda', 30),
  Person.new(2, 'ieyasu', 'tokugawa', 50),
]

# factory method for collection
PersonPresenter.collection(people)

Computed Attributes

class PersonPresenter < Hb::Base
  attributes :id, :email, :full_name
  def full_name
    "#{object.first_name} #{object.last_name}"
  end
end

# => { id: 1, email: 'shozawa@sample.com', full_name: 'tomohiro shozawa' }

object is the object to be wrapped.

Transforming Keys

# pass method_name
Hb::Base.key_format :upcase
PersonPresenter.new(person).to_h
# => { "ID" => 1, "EMAIL" => 'shozawa@sample.com', "FULL_NAME": ... }

# with options
Hb::Base.key_format camelize: :lower
PersonPresenter.new(person).to_h
# => { "id" => 1, "email" => 'shozawa@sample.com', "fullName": ... }

# you can pass proc
Hb::Base.key_format -> (k) { '_' + k }
PersonPresenter.new(person).to_h
# => { "_id" => 1, "_email" => 'shozawa@sample.com', "_full_name": ... }

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/shozawa/hb.