Tuples

Cassandra 2.1 introduced a tuple type for CQL.

A tuple is a fixed-length set of typed positional fields. With the driver, you retrieve and store tuples using the Tuple class.

For example, given the following table to represent the value of the exchange between two currencies.

CREATE TABLE forex (
   name text,
   time timeuuid,
   currencies frozen<tuple<text, text>>,
   value decimal,
   PRIMARY KEY (name, time)
);

To retrieve the Tuple value:

const query = 'SELECT name, time, currencies, value FROM forex where name = ?';
client.execute(query, [name], { prepare: true })
  .then(function (result) {
    result.rows.forEach(function (row) {
      console.log('%s to %s: %s', row.currencies.get(0), row.currencies.get(1), row.value);
    });
  });

You use the get(index) method to obtain the value at any position or the values() method to obtain an Array representation of the Tuple.

To create a new Tuple, you use the constructor providing the values as parameters.

const { Tuple, BigDecimal, TimeUuid } = require('cassandra-driver').types;

// Create a new instance of a Tuple.
const currencies = new Tuple('USD', 'EUR');
const query = 'INSERT INTO forex (name, time, currencies, value)  VALUES (?, ?, ?, ?)';
const params = ['market1', TimeUuid.now(), currencies, new BigDecimal(1, 0)];
client.execute(query, params, { prepare: true });