TenderHash

Map hashes with style.

Installation

Add this line to your application's Gemfile:

gem 'tender_hash'

And then execute:

$ bundle

Or install it yourself as:

$ gem install tender_hash

Usage

An empty set of rules will filter all keys returning an empty hash.

TenderHash.map( { name: 'Rodrigo', age: 27 } )

The key method will cause the mapper to keep the specified key without making any changes.

TenderHash.map( { name: 'Rodrigo', age: 27 } ) do
  key :name
end

# => { name: 'Rodrigo' }

The map_key methods allows to define mappings for the hash keys.

TenderHash.map( { name: 'Rodrigo', age: 27 } ) do
  map_key :name, :first_name
end

# => { first_name: 'Rodrigo' }

The key and map_key methods accept a default option. If the input hash doesn't have the key defined or if it's value is nil, then the default value will be set for that key on the returned hash.

TenderHash.map( { name: 'Rodrigo', age: 27 } ) do
  map_key :name, :first_name, default: 'John Doe'
  key :height, default: 1.90
end

# => { first_name: 'Rodrigo', height: 1.90 }

The key and map_key methods also accept a cast_to option. The possible alternatives are: :integer, :string, :boolean and any object that responds to #call.

TenderHash.map( { name: 'Rodrigo', age: 27, logged_in: 'false' } ) do
  key :age,       cast_to: :string
  key :logged_in, cast_to: :boolean
  key :name,      cast_to: -> (v) { v.upcase }
end

# => { age: '27', looged_in: false, name: 'RODRIGO' }

The scope method allows to nest a hash within a key.

TenderHash.map( { name: 'Rodrigo', age: 27, logged_in: 'false' } ) do
  scope :personal_info do
    map_key :name, :first_name
    key :age
  end

  key :logged_in
end

# => {
#       personal_info: {
#         first_name: 'Rodrigo',
#         age: 27
#       },
#       logged_in: 'false'
#    }

A good use case for this gem is to map the ENV hash into a more readable and usable hash.

TenderHash.map(ENV) do
  map_key 'EMAIL_NOTIFICATIONS', :send_email_notifications, cast_to: :boolean, default: true
  map_key 'MAPS_API_AUTH_TOKEN', :api_auth_token

  scope :database do
    map_key 'POSTGRES_URL',      :url, default: 'localhost'
    map_key 'PORT',              :port, cast_to: :integer, default: 5432
  end
end

# => {
#       send_email_notifications: true,
#       api_auth_token: 'super-secret',
#       database: {
#         url: 'localhost',
#         port: 5432
#       }
#    }

Contributing

1. Fork it ( https://github.com/rodrei/tender_hash/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request