AsyncMysqlRowBlock::getFieldAsDouble

Get a certain field (column) value from a certain row as double.

Description

public function getFieldAsDouble(
  int $row,
  mixed $field,
): float

Get a certain field (column) value from a certain row as double.

If the column from which you are retrieving the value is not an numeric type, then an Exception is thrown.

Parameters

  • int $row - the row index.
  • mixed $field - the field index (int) or field name (string).

Return Values

  • float - The double value of the field (column); or an Exception if it the column is not numeric.

Examples

The following example shows how to get a field value as a float value via AsyncMysqlRowBlock::getFieldAsDouble. Assume this was the SQL used to create the example table:

CREATE TABLE test_table (
userID SMALLINT UNSIGNED ZEROFILL NOT NULL AUTO_INCREMENT,
name VARCHAR(40) NOT NULL,
age SMALLINT NULL,
email VARCHAR(60) NULL,
PRIMARY KEY (userID)
);

In this case, we are actually getting a field that is an int (or SMALLINT). But there is an automatic conversion to a float.

<?hh

namespace Hack\UserDocumentation\API\Examples\AsyncMysql\RowBlock\GFAsDouble;

use \Hack\UserDocumentation\API\Examples\AsyncMysql\ConnectionInfo as CI;

async function connect(\AsyncMysqlConnectionPool $pool):
  Awaitable<\AsyncMysqlConnection> {
  return await $pool->connect(
    CI::$host,
    CI::$port,
    CI::$db,
    CI::$user,
    CI::$passwd
  );
}
async function simple_query(): Awaitable<float> {
  $pool = new \AsyncMysqlConnectionPool(array());
  $conn = await connect($pool);
  $result = await $conn->query(
    'SELECT * FROM test_table WHERE userID < 50'
  );
  $conn->close();
  // A call to $result->rowBlocks() actually pops the first element of the
  // row block Vector. So the call actually mutates the Vector.
  $row_blocks = $result->rowBlocks();
  if ($row_blocks->count() > 0) {
    // An AsyncMysqlRowBlock
    $row_block = $row_blocks[0];
    return $row_block->getFieldAsDouble(0, 'age'); // int will be a float value
  } else {
    return -1.0;
  }
}

function run(): void {
  $r = \HH\Asio\join(simple_query());
  var_dump($r);
}

run();
Output
float(41)