hphp/hack/manual/apis/Classes/AsyncMysqlRow/isNull.md
:::info[Note] This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information. :::
Returns whether a field (column) value is null
public function isNull(
mixed $field,
): bool;
mixed $field - the field index (int) or field name (string).bool - true if the column value is null; false otherwise.The following example uses AsyncMysqlRow::isNull to check if a field value is null (e.g., if a field was set in SQL to something like age SMALLINT NULL, then that field could be null).
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<int> {
$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->isEmpty()) {
// An AsyncMysqlRowBlock
$row_block = $row_blocks[0];
if (!$row_block->isEmpty()) {
// An AsyncMysqlRow
$row = $row_block->getRow(0);
if (!$row->isNull("age")) {
return $row->getFieldAsInt("age");
}
return -1;
}
return -1;
} else {
return -1;
}
}
<<__EntryPoint>>
async function run(): Awaitable<void> {
$r = await simple_query();
\var_dump($r);
}
```.hhvm.expectf
int(%d)
```.example.hhvm.out
int(42)
```.skipif
await \Hack\UserDocumentation\API\Examples\AsyncMysql\skipif_async();