Introduction to WP-Cron

[jonathanbossenger]

Details

• Content type (Online Workshop, Lesson, Course, Tutorial, or Lesson Plan): Lesson
• Content title: Introduction to WP-Cron
• Topic description: Introduce WP-Cron, why we need it, and how it works
• Audience (User, Developer, Designer, Contributor, etc.): Developer
• Experience Level (Beginner, Intermediate, Advanced, Any): Intermediate

Learning Objectives

• Explain what WP-Cron is
• Differentiate between WP-Cron and a server cron
• Explain why we need WP-Cron
• Briefly describe the request flow of a WP-Cron task

Related Resources and Other Notes

• https://developer.wordpress.org/plugins/cron/

Automation Code

//lesson

[github-actions]

Lesson Development Checklist

• Gather any relevant links to Support, Docs, or related material
• Description and Objectives finalized
• Lesson created and announced to the team for review
• Lesson reviewed
• Lesson video submitted and published to WPTV
• Lesson created on Learn.WordPress.org
• Lesson video published to YouTube
• Lesson on Learn.WordPress.org updated with YouTube video
• Lesson published to Learn.WordPress.org

[jonathanbossenger]

@CrochetFeve0251 In reviewing the Cron module, I realized I left out an important introduction lesson, so I've added it here with the lesson description/objectives. Would you be okay with starting with this one first?

[CrochetFeve0251]

@jonathanbossenger Yes that would be fine for you

[CrochetFeve0251]

I added a first version from the script: wptrainingteam/learn-wp-content#18

Tell me if you think I should add more on these two points:

• Explain why we need WP-Cron
• Briefly describe the request flow of a WP-Cron task

[jonathanbossenger]

Thanks @CrochetFeve0251. I will be reviewing the script this week, and I'll get back to you.

[jonathanbossenger]

Script: https://github.com/wptrainingteam/learn-wp-content/blob/main/plugin-developer-learning-pathway/12-Cron/01-Introduction-to-WP-Cron.md

[jonathanbossenger]

Video for review: https://drive.google.com/file/d/1K62qS8B2FbaiMI8NWU21UzuI3_3RlphF/view?usp=drive_link

[digitalchild]

When you switch to talking about cron in general, I wonder if there needs to be more of a bridging sentence as to why this is relevant in the relation to wp-cron. You do mention this at the end of the section, but I'm wondering if it should start with this?

• Learning outcomes/objectives are clear.
• Technical concepts introduced in the content are accurate.
• The speed of demonstrations are easy to follow.
• The narration audio matches what is shown visually.
• Spelling and grammar are correct.
• Sound quality is consistent throughout the video.
• Brand Usage Guidelines and Promotional Guidelines are being followed.
• Media assets are all in the public domain (CC0).

[benazeer-ben]

Tutorial/Lessons Review Checklist

Please tick all items you've confirmed:

• Learning outcomes/objectives are clear.
• Technical concepts introduced in the content are accurate.
• The speed of demonstrations are easy to follow.
• The narration audio matches what is shown visually.
• Spelling and grammar are correct.
• Sound quality is consistent throughout the video.
• Brand Usage Guidelines and Promotional Guidelines are being followed.
• Media assets are all in the public domain (CC0).

The script covers all necessary points, and is easy to understand.

Here are a few additional points that I believe improve the script, making it more suitable for developer documentation:

Introduction to WP Cron

WP-Cron is WordPress's built-in task scheduling system. It allows developers to schedule tasks (e.g., publishing scheduled posts, sending emails, or running periodic updates) without relying on server-level cron jobs.

WP-Cron is not a "real" cron system. Instead, it relies on website traffic to trigger scheduled tasks.

How WP-Cron Works: Request Flow

• Task Scheduling: A task is scheduled using wp_schedule_event() or similar functions.
• Task Storage: The task is stored in the WordPress database (wp_options table with the cron key).
• Triggering: When a user visits the site, WordPress checks if any scheduled tasks are due.
• Execution: If a task is due, WordPress runs it by making an HTTP request to itself (a "cron request").
• Completion: The task is executed, and the schedule is updated for the next run.

Example: Scheduling a Task with WP-Cron

// Schedule a recurring event
if (!wp_next_scheduled('my_custom_task_hook')) {
    wp_schedule_event(time(), 'hourly', 'my_custom_task_hook');
}

// Hook the task to a function
add_action('my_custom_task_hook', 'my_custom_task_function');

function my_custom_task_function() {
    // Task logic here
    error_log('Custom task executed at ' . current_time('mysql'));
}