Input validator step using Parametric

params_validator_step.rb

# https://github.com/ismasan/parametric

require 'parametric'

class InputValidator
  def initialize(&block)
    @schema = Parametric::Schema.new(&block)
  end

  # @param result [Result]
  # @return [Result]
  def call(result)
    params = result.params
    out = @schema.resolve(params)
    if out.valid?
      result.continue(params: params.merge(out.output))
    else
      result.halt(errors: result.errors.merge(out.errors))
    end
  end
end