gistfile1.rb

customer = Stripe::Customer.retrieve(u.customer_id, user.token)
=> #<Stripe::Customer:0x3fc8248fa328 id=cus_53Vyl3MA0F6eMk> JSON: {
  "id": "cus_53VyK6MA0F6eMk",
  "object": "customer",
  "created": 1414698626,
  "livemode": false,
  "description": null,
  "email": null,
  "delinquent": false,
  "metadata": {},
  "subscriptions": {"object":"list","total_count":0,"has_more":false,"url":"/v1/customers/cus_53VyK6MA0F6eMk/subscriptions","data":[]},
  "discount": null,
  "account_balance": 0,
  "currency": null,
  "cards": {"object":"list","total_count":1,"has_more":false,"url":"/v1/customers/cus_53VyK6MA0F6eMk/cards","data":[{"id":"card_14tOwA2Rfd38UhRTeTS8MyQ6","object":"card","last4":"4242","brand":"Visa","funding":"credit","exp_month":1,"exp_year":2018,"fingerprint":"F5nktbqmrfjweIQk","country":"US","name":null,"address_line1":null,"address_line2":null,"address_city":null,"address_state":null,"address_zip":null,"address_country":null,"cvc_check":"pass","address_line1_check":null,"address_zip_check":null,"dynamic_last4":null,"customer":"cus_53VyK6MA0F6eMk"}]},
  "default_card": "card_14tOwA2Rfd38UhRTeTS8MyQ6"
}