How to Create a Scheduled Job

In this document, you’ll learn how to create a scheduled job in Medusa.

Overview

Medusa allows you to create scheduled jobs that run at specific times during your backend's lifetime. For example, you can synchronize your inventory with an Enterprise Resource Planning (ERP) system once a day.

This guide explains how to create a scheduled job on your Medusa backend. The scheduled job in this example will simply change the status of draft products to published.

Prerequisites

Medusa Components

It is assumed that you already have a Medusa backend installed and set up. If not, you can follow the quickstart guide to get started. The Medusa backend must also have an event bus module installed, which is available when using the default Medusa backend starter.

1. Create a File

Each scheduled job should reside in a TypeScript or JavaScript file under the src/loaders directory.

Start by creating the src/loaders directory. Then, inside that directory, create the JavaScript or TypeScript file that you’ll add the scheduled job in. You can use any name for the file.

For the example in this tutorial, you can create the file src/loaders/publish.ts.

2. Create Cron Job

To create a scheduled job, add the following code in the file you created, which is src/loaders/publish.ts in this example:

src/loaders/publish.ts

const publishJob = async (container, options) => {
  const jobSchedulerService = 
    container.resolve("jobSchedulerService")
  jobSchedulerService.create(
    "publish-products", 
    {}, 
    "0 0 * * *", 
    async () => {
      // job to execute
      const productService = container.resolve("productService")
      const draftProducts = await productService.list({
        status: "draft",
      })

      for (const product of draftProducts) {
        await productService.update(product.id, {
          status: "published",
        })
      }
    }
  )
}

export default publishJob
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The service taking care of background jobs was renamed in v1.7.1. If you are running a previous version, use eventBusService instead of jobSchedulerService.

This file should export a function that accepts a container and options parameters. container is the dependency container that you can use to resolve services, such as the JobSchedulerService. options are the plugin’s options if this scheduled job is created in a plugin.

You then resolve the JobSchedulerService and use the jobSchedulerService.create method to create the scheduled job. This method accepts four parameters:

The first parameter is a unique name to give to the scheduled job. In the example above, you use the name publish-products;
The second parameter is an object which can be used to pass data to the job;
The third parameter is the scheduled job expression pattern. In this example, it will execute the scheduled job once a day at 12 AM.
The fourth parameter is the function to execute. This is where you add the code to execute once the scheduled job runs. In this example, you retrieve the draft products using the ProductService and update the status of each of these products to published.

You can see examples of scheduled job expression patterns on crontab guru.

Pass Data to the Cron Job

To pass data to your scheduled job, you can add them to the object passed as a second parameter under the data property. This is helpful if you use one function to handle multiple scheduled jobs.

For example:

jobSchedulerService.create("publish-products", {
    data: {
      productId,
    },
  }, "0 0 * * *", async (job) => {
    console.log(job.data) // {productId: 'prod_124...'}
    // ...
})
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3. Run Medusa Backend

Cron Jobs only run while the Medusa backend is running.

Before you run the Medusa backend, make sure to build your code that's under the src directory into the dist directory with the following command:

npm
Yarn

npm run build

yarn run build

Then, run the following command to start your Medusa backend:

npm
Yarn

npm run start

yarn run start

If the scheduled job was registered successfully, you should see a message similar to this logged on your Medusa backend:

Registering publish-products

Where publish-products is the unique name you provided to the scheduled job.

Once it is time to run your scheduled job based on the scheduled job expression pattern, the scheduled job will run and you can see it logged on your Medusa backend.

For example, the above scheduled job will run at 12 AM and, when it runs, you can see the following logged on your Medusa backend:

info:    Processing scheduled job: publish-products
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If you log anything in the scheduled job, for example using console.log, or if any errors are thrown, it’ll also be logged on your Medusa backend.

To test the previous example out instantly, you can change the scheduled job expression pattern passed as the third parameter to jobSchedulerService.create to * * * * *. This will run the scheduled job every minute.

How to Create a Scheduled Job

Overview​

Prerequisites​

Medusa Components​

1. Create a File​

2. Create Cron Job​

Pass Data to the Cron Job​

3. Run Medusa Backend​

See Also​