DocumentationHackReferenceClassAsyncMysqlRowBlockgetFieldAsDouble

AsyncMysqlRowBlock::getFieldAsDouble

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

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

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).

Returns

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.

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(darray[]);
  $conn = await connect($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;
  }
}

<<__EntryPoint>>
async function run(): Awaitable<void> {
  $r = await simple_query();
  \var_dump($r);
}
```.hhvm.expectf
float(%f)
```.example.hhvm.out
float(42)
```.skipif
await \Hack\UserDocumentation\API\Examples\AsyncMysql\skipif_async();