Strong Parameters -- HowTo Custom PERMITTED_SCALAR_TYPES

strong_paramters_permitted_scaler_values.rb

# config/initializers/strong_paramters_permitted_scaler_values.rb

ActionController::Parameters.send :define_method, :permitted_scalar? do |value|
  [String,
    Symbol,
    NilClass,
    Numeric,
    TrueClass,
    FalseClass,
    Date,
    Time,
    # DateTimes are Dates, we document the type but avoid the redundant check.
    StringIO,
    IO,
    ActionDispatch::Http::UploadedFile,
    Rack::Test::UploadedFile,
    MyClass # Throw anything you want in this array to whitelist it.
    ].any? {|type| value.is_a?(type)}
end

What I'm doing is redefining the method here https://github.com/rails/strong_parameters/blob/master/lib/action_controller/parameters.rb#L149 to be something I want.