gem 'validate_params'

class ExamplesController < ApplicationController
  include ValidateParams

  def create
    validate_params! :example
    # [...]
  end
end

class ApplicationController < ActionController::Base
  rescue_from InvalidParamsException do |exception|
    respond_to do |format|
      format.json { render json: { error: exception.to_s }, status: 400 }
      format.html { raise ActionController::RoutingError.new('Not found') }
    end

  end
end

validate_params! :user

validate_params! :user, :token

validate_params! user: Array

validate_params! user: { type: Array }

validate_params! user: Array, token: String

validate_params! example: { type: Array, size: 2 }

validate_params! number: { range: 0..10 }

validate_params! example: { in: %w(value1 value2) }

validate_params! example: { regex: /myregex/ }

validate_params! example: { custom: Proc.new { |value| value == 'a' } }

validate_params! example: { default: 'abc' }

# :Integer :Float or :Array
validate_params! example: { cast: :Integer }