StrongLocals

Methods have signatures, React has PropTypes, but Rails partials don't provide a way to declare what local variables they expect to receive. StrongLocals aims to help with that, by providing validations for the incoming locals to the partial.

In HAML:

:ruby
  StrongLocals.
    add(:currency).
    add(:campaign, presence: false).
    validate!(local_assigns)

In ERB:

<%
StrongLocals.
  add(:currency).
  add(:campaign, presence: false).
  validate!(local_assigns)
%>

If the locals passed to the partial don't pass the validation, a StrongLocals::LocalsException exception will be raised which contains the error information.

First define a validation class which extends from StrongLocals::Validations::Base. It should contain a MESSAGE and a valid? method which checks to confirm that the value being validated conforms to the validation.

class StringValidation < StrongLocals::Validations::Base
  MESSAGE = 'not string'.freeze

  def valid?
    value.respond_to?(:to_s)
  end
end

Next, register your new validation so that StrongLocals knows about it.

StrongLocals::Locals.register :string, StringValidation