This function will help you determine whether an item is already added to the queue or not. Note: only works when using the database queue driver.

laravel-check-if-item-is-already-added-to-the-queue.php

<?php

/*
Example usage:

// The payload of the job
$userQueueItem = [
	'id'	   => 5,
	'username' => 'user',
	'email'    => 'user@mail.com',
];

// Pass the job name (including namespace), the user queue item we would like to check if is already added to the queue, and then the function closure which will match each queue item against our user queue item
$alreadyAddedToQueue = itemAlreadyAddedToQueue('App\Jobs\CalculateLoyaltyPoints', $userQueueItem, function($jobParameters, $userQueueItem) {
	return $jobParameters['id'] === $userQueueItem['id'];
});

if ( ! alreadyAddedToQueue ) {
	// Only dispatch job if the user queue item is not already in the queue
	CalculateLoyaltyPoints::dispatch($userQueueItem);
}
*/

if ( ! function_exists('itemAlreadyAddedToQueue') )
{
	/**
	 * Check if an item is already in the queue (only works with the Database queue driver).
	 *
	 * @param $item
	 * @param $closure
	 * @param $jobName
	 *
	 * @return bool
	 */
	function itemAlreadyAddedToQueue($item, $closure, $jobName = false)
	{
		$alreadyAdded = false;
		$queue = \DB::table(config('queue.connections.database.table'))->get();
		$queue->each(function($queueItem) use ($item, $closure, $jobName, &$alreadyAdded) {

			// Decode the queue data
			$decodedJobPayload = json_decode($queueItem->payload,true);

			// This is not the queue item we are looking for
			if ( $jobName !== false && $decodedJobPayload['displayName'] !== $jobName ) {
				return true; // Continue
			}

			// Get job parameters
			$data = data_get($decodedJobPayload, 'data', []);
			$jobParameters = unserialize(data_get($data, 'command', ''));

			// Could not get any parameters
			if ( ! $jobParameters ) {
				return true; // Continue
			}

			// Determine result with closure
			if ( is_callable($closure) && $closure($jobParameters, $item) === true ) {
				$alreadyAdded = true;
				return false; // Break loop
			}
		});
		return $alreadyAdded;
	}
}