Validating hash params in ruby
Jan 27, 2015

If compare many arguments vs “options” hash, I usually choose options hash. And I often face problems when I pass wrong key name or what not supported.

ActiveSupport already have Hash#assertvalidkeys, I added one more method assert_required_keys:

class Hash
  def assert_required_keys(*keys)
    keys.flatten.each do |key|
      raise ArgumentError.new("Required key: #{key.inspect}") unless has_key?(key)
    end
  end
end

Here is my solution to validate hash keys:

module ValidateOptions
  def validate_options!(params, options)
    options[:optional] ||= []
    options[:required] ||= []

    params = params.deep_symbolize_keys
    params.assert_required_keys(options[:required])
    params.assert_valid_keys(options[:required] + options[:optional])
  end
end

Usage example:

include ValidateOptions

def method_with_options(options = {})
  validate_options!(options,
    required: [:order_id, :subject, :from, :to, :text_body, :html_body],
    optional: [:cc, :bcc, :template_name]
  )
end