Important note: This will only detect whether a transaction has been started using beginTransaction(). It will not be able to detect transactions started by any other means, for example by executing "START TRANSACTION".
(PHP 5 >= 5.3.3, Bundled pdo_pgsql, PHP 7, PHP 8)
PDO::inTransaction — Comprueba si una transacción está activa
Comprueba si una transacción está actualmente activa dentro del controlador. Este método únicamente funciona para controladores de bases de datos que admitan transacciones.
Esta función no tiene parámetros.
Devuelve true si una transacción está activa actualmente, y false si no.
Important note: This will only detect whether a transaction has been started using beginTransaction(). It will not be able to detect transactions started by any other means, for example by executing "START TRANSACTION".
At least for MySQL/MariaDB, inTransaction shows the real state of the transaction since 8.0
In addition to what jlh says,
even with SQLite3 which automatically starts transaction,
inTransaction() only works after beginTransaction().
<?php
try{
$pdo = new PDO('sqlite:test.sql3', null, null, [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION]);
var_dump($pdo->inTransaction());echo "<br>"; // bool(false) : before beginTransaction()
$pdo->beginTransaction();
var_dump($pdo->inTransaction());echo "<br>"; // bool(true) : after beginTransaction()
$pdo->rollBack();
var_dump($pdo->inTransaction());echo "<br>"; // bool(false) : after commit() or rollBack()
}catch (PDOException $e){
echo 'PDOException: ' . $e->getMessage();
}catch (Exception | ErrorException $e){
var_dump($e);
}