Handlers

A runnable Geblang example.

Path

gebweb/examples/feature_tour/src/handlers.gb

Category

Feature Tour

Source

module feature_tour.handlers;

/**
 * Consumer-side bits of the tasks app: an event subscriber that
 * watches for completed tasks and enqueues a notification email,
 * a job handler that wraps the Gebweb mailer for that email,
 * and a scheduled cleanup that prunes old completed rows once a
 * day. The worker process (`gebweb worker`) ticks both the job
 * queue and the scheduler.
 */

import gebweb;
import datetime;

/** Subscribe to the task.completed event. Enqueues a background
 *  job so the response returns immediately - the mail send goes
 *  through the worker's retry/backoff. */
export class TaskNotifier {
    @On("task.completed")
    func onCompleted(gebweb.Event ev): void {
        gebweb.enqueue(ev.app, "send-task-notification", ev.payload);
    }
}

/** A Mailable for the completion notification. */
export class TaskCompletedMail extends gebweb.Mailable {
    string title;
    string taskId;

    func TaskCompletedMail(string to, string title, string taskId) {
        parent();
        this.to = to;
        this.title = title;
        this.taskId = taskId;
    }

    func subject(): string {
        return "Task completed: " + this.title;
    }

    func template(): string {
        return "emails/task-completed.html";
    }

    func context(): dict<string, any> {
        return {"title": this.title, "taskId": this.taskId};
    }
}

/** Job handler invoked by the worker. Wraps the mailer so the
 *  delivery retries on failure under the standard backoff. */
export class TaskNotificationJob {
    @Job("send-task-notification")
    func send(gebweb.Job job): void {
        let payload = job.payload;
        let mail = TaskCompletedMail(
            payload["ownerEmail"] as string,
            payload["title"] as string,
            payload["taskId"] as string
        );
        gebweb.send(job.app, mail);
    }
}

/** Daily scheduled cleanup: purge tasks completed more than
 *  30 days ago. Runs on the leader worker only. */
export class TaskCleanup {
    any repo;

    func TaskCleanup(any repo) {
        this.repo = repo;
    }

    @Scheduled("0 3 * * *")
    func nightlyPurge(): void {
        let cutoff = datetime.nowUnix() - (30 * 24 * 3600);
        this.repo.purgeOldCompleted(cutoff);
    }
}