Cron Tasks

Bialet allows you to run scheduled code by defining a cron job in a Wren file.

This is useful for running periodic operations like cleaning old records, sending emails, or syncing external data.

The cron file can be in the root and be called _cron.wren or be inside the _app folder, _app/cron.wren.

Basic Usage

To schedule a task, use the Cron.every or Cron.at helpers methods inside the Wren cron file. These methods receive a block that is called at the specified time.

import "_app/domain" for Task

// Every 2 minutes
Cron.every(2) { |date| System.log("Hello, from Cron!") }

// At 2:00 AM
Cron.at(2, 0) { |date| Task.clearAll() }

The |date| argument is the current Date object used for evaluation. You can ignore it if not needed.

Helper methods

Cron.every(minutes)

Runs the job when the current minute is divisible by minutes.

Cron.every(10) { |d| System.log("Runs every 10 minutes") }

Important: Cron.every(n) uses divisibility, not elapsed time. Cron.every(7) fires at minutes 0, 7, 14, 21, 28, 35, 42, 49, 56, then skips 4 minutes to 0 again. Cron.every(90) never fires because 90 does not divide 60. Use these safe values: 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30.

Cron.at(hour, minute, dayOfWeek)

Runs the job when the current time matches the given hour and minute.

Cron.at(3, 15) { |d| System.log("Runs at 03:15 every day") }

Runs the job when the current time matches the given hour, minute, and day of week. Days of week: 0 (Sunday) to 6 (Saturday)

Cron.at(4, 30, 1) { |d| System.log("Runs at 04:30 every Monday") }

Custom Rules

Each job receives a Date object of the current time, which can be used for custom rules.

Cron.every(1) { |d|
  if (d.day == 1 && d.hour == 0) {
    System.log("It's the first of the month!")
  }
}