Failed job handling in Laravel - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a failed job in Laravel?

A failed job is a queued task that did not complete successfully due to an error or exception during its execution.

beginner

How does Laravel store failed jobs by default?

Laravel stores failed jobs in a database table called failed_jobs which keeps details like the job payload, error message, and failure time.

beginner

Which Artisan command is used to retry all failed jobs in Laravel?

The command php artisan queue:retry all retries all jobs listed in the failed jobs table.

intermediate

What is the purpose of the failed() method in a Laravel job class?

The failed() method lets you define custom logic to run when a job fails, such as sending notifications or cleaning up resources.

intermediate

How can you configure Laravel to automatically delete failed jobs after a certain time?

You can schedule the queue:prune-failed Artisan command in Laravel's scheduler to remove failed jobs older than a specified number of days.

Where does Laravel store failed jobs by default?

A In the <code>failed_jobs</code> database table

B In the <code>jobs</code> table

C In log files only

D In cache memory

Laravel uses the failed_jobs table to keep track of jobs that did not complete successfully.

Which command retries a specific failed job by its ID?

A php artisan queue:retry {id}

B php artisan queue:work {id}

C php artisan queue:flush {id}

D php artisan queue:forget {id}

The queue:retry {id} command retries the failed job with the given ID.

What method can you add to a job class to handle failure logic?

A failHandler()

B handleFailure()

C onFail()

D failed()

The failed() method is called automatically when a job fails.

How do you remove all failed jobs from the database?

A php artisan queue:forget

B php artisan queue:clear

C php artisan queue:flush

D php artisan queue:prune-failed

The queue:flush command deletes all records from the failed jobs table.

What should you do to handle failed jobs gracefully in production?

A Ignore failed jobs as they fix themselves

B Implement the <code>failed()</code> method and monitor failed jobs regularly

C Delete the failed jobs table

D Disable the queue system

Handling failures with the failed() method and monitoring helps keep your app stable.

Explain how Laravel handles failed jobs and how you can retry them.

Think about where failures are saved and how you can fix them.

Describe how to clean up old failed jobs automatically in Laravel.

Consider how to keep the failed jobs table tidy over time.

Practice

1. What is the primary purpose of the failed() method in a Laravel job class?

easy

A. To list all failed jobs in the queue

B. To retry a failed job automatically

C. To define actions when a queued job fails during execution

D. To clear all failed jobs from the database

Solution

1. Step 1: Understand the role of failed() method

   The failed() method is a special method in Laravel job classes that runs when the job fails after all retry attempts.

2. Step 2: Identify what failed() does

   This method allows you to define custom logic like sending notifications or logging when a job fails.

3. Final Answer:

   To define actions when a queued job fails during execution -> Option C

4. Quick Check:

   failed() handles failure actions [OK]

Hint: Remember: failed() runs only on job failure [OK]

Common Mistakes:

• Confusing failed() with retry commands
• Thinking it lists or clears failed jobs
• Assuming it runs on successful job completion

2. Which of the following is the correct Artisan command to retry all failed jobs in Laravel?

easy

A. php artisan queue:retry all

B. php artisan queue:retry --all

C. php artisan queue:retry --failed

D. php artisan queue:retry --all-jobs

Solution

1. Step 1: Recall the syntax for retrying failed jobs

   Laravel's command to retry failed jobs is php artisan queue:retry followed by the job IDs or all to retry all.

2. Step 2: Identify the correct option

   The correct command to retry all failed jobs is php artisan queue:retry all.

3. Final Answer:

   php artisan queue:retry all -> Option A

4. Quick Check:

   Retry all failed jobs = queue:retry all [OK]

Hint: Use 'all' after retry to retry every failed job [OK]

Common Mistakes:

• Adding extra flags like --all or --failed which don't exist
• Using incorrect command syntax
• Confusing retry with clear commands

3. Given this Laravel job class snippet, what will happen when the job fails?

class SendEmailJob implements ShouldQueue {
    public function handle() {
        // code that throws an exception
    }
    public function failed(Exception $exception) {
        Log::error('Email sending failed: ' . $exception->getMessage());
    }
}

medium

A. The job will be retried indefinitely without logging

B. The job will succeed despite the exception

C. The job will be removed silently without any action

D. The job failure will be logged with the error message

Solution

1. Step 1: Analyze the failed() method implementation

   The failed() method logs an error message when the job fails due to an exception.

2. Step 2: Understand job failure behavior

   When the job throws an exception, Laravel calls failed() and logs the failure message.

3. Final Answer:

   The job failure will be logged with the error message -> Option D

4. Quick Check:

   failed() logs failure message [OK]

Hint: Check if failed() logs or retries [OK]

Common Mistakes:

• Assuming job retries indefinitely without limit
• Thinking failure is ignored without logging
• Believing job succeeds despite exception

4. Consider this command to clear failed jobs:

php artisan queue:flush

What is the issue with this command?

medium

A. It clears all failed jobs correctly

B. The command does not exist; the correct command is queue:forget

C. It retries all failed jobs instead of clearing

D. It only clears jobs from the default queue, not all queues

Solution

1. Step 1: Verify the correct command to clear failed jobs

   The php artisan queue:flush command does not exist in Laravel. The correct command to remove failed jobs is php artisan queue:forget {id} for specific jobs or manually clearing the failed_jobs table.

2. Step 2: Confirm the issue

   Since queue:flush is not a valid command, it cannot clear failed jobs.

3. Final Answer:

   The command does not exist; the correct command is queue:forget -> Option B

4. Quick Check:

   queue:flush is invalid; use queue:forget [OK]

Hint: Remember: queue:flush is not a valid Artisan command [OK]

Common Mistakes:

• Thinking queue:flush does not exist
• Confusing it with queue:forget for specific jobs
• Mistaking it for a retry command

5. You want to notify the admin by email whenever a job fails in Laravel. Which approach correctly implements this using the failed() method?

hard

A. Add a failed() method in the job class that sends an email notification to the admin

B. Use php artisan queue:notify-admin command after job failure

C. Configure the failed_jobs table to send emails automatically

D. Set notify_admin = true in the job constructor

Solution

1. Step 1: Understand how to handle job failure notifications

   Laravel allows defining a failed() method in job classes to run custom logic on failure, such as sending emails.

2. Step 2: Identify the correct implementation

   Adding a failed() method that sends an email notification to the admin is the correct way to notify on failure.

3. Final Answer:

   Add a failed() method in the job class that sends an email notification to the admin -> Option A

4. Quick Check:

   Use failed() to notify admin on job failure [OK]

Hint: Put notification code inside failed() method [OK]

Common Mistakes:

• Expecting Artisan commands to notify admin automatically
• Assuming database config sends emails
• Trying to set flags in constructor for notifications