{
  "properties" : {
    "class": {
      "type" : "keyword"
    },
    "user": {
      "type" : "keyword"
    },
    "item": {
      "type" : "keyword"
    },
    "quantity": {
      "type" : "long"
    },
    "amount": {
      "type" : "long"
    },
    "purchase_time": {
      "type" : "date",
      "format": "yyyy-MM-dd HH:mm:ss"
    }
  }
}