Rails Support

Rails plugin is implemented in a separate dry-initializer-rails gem.

It provides coercion of assigned values to corresponding ActiveRecord instances.

Base Example

Add the :model setting to param or option:

require 'dry-initializer-rails'

class CreateOrder
  extend Dry::Initializer
  extend Dry::Initializer::Rails

  # Params and options
  param  :customer, model: 'Customer' # use either a name
  option :product,  model: Product    # or a class

  def call
    Order.create customer: customer, product: product
  end
end

Now you can assign values as pre-initialized model instances:

customer = Customer.find(1)
product  = Product.find(2)

order = CreateOrder.new(customer, product: product).call
order.customer # => <Customer @id=1 ...>
order.product  # => <Product @id=2 ...>

…or their ids:

order = CreateOrder.new(1, product: 2).call
order.customer # => <Customer @id=1 ...>
order.product  # => <Product @id=2 ...>

The instance is envoked using method find_by(id: ...).
With wrong ids nil values are assigned to corresponding params and options:

order = CreateOrder.new(0, product: 0).call
order.customer # => nil
order.product  # => nil

Custom Keys

You can specify custom key for searching model instance:

require 'dry-initializer-rails'

class CreateOrder
  extend Dry::Initializer
  extend Dry::Initializer::Rails

  param  :customer, model: 'User', find_by: 'name'
  option :product,  model: Item,   find_by: :name
end

This time you can send names (not ids) to the initializer:

order = CreateOrder.new('Andrew', product: 'the_thing_no_123').call

order.customer # => <User @name='Andrew' ...>
order.product  # => <Item @name='the_thing_no_123' ...>

Container Syntax

If you prefer container syntax, extend plugin inside the block:

require 'dry-initializer-rails'

class CreateOrder
  include Dry::Initializer.define -> do
    extend Dry::Initializer::Rails

    # ... params/options declarations
  end
end

Types vs Models

Type constraints are checked before the coercion.

When mixing :type and :model settings for the same param/option, you should use sum types that accept both model instances and their attributes.