title: Adding one model to another rails
body: <p>I'm trying to come up with a way to let a customer add themselves to a category. Meaning - I want to be able to call in my views @customer.add_to_category(category), or similar. Any suggestions?</p>
  
  <pre><code>class Category &lt; ActiveRecord::Base
  #Associations
  
  
  has_many :customers
  
  #Defs
  def add_customer(customer_id)
      current_customer = Customer.find_by(customer_id: customer_id)
      if current_customer
          current_customer = Customer.build(customer_id: customer_id) 
      end
      current_customer
  end
  end
  </code></pre>