JSDB Migrations

16 May 2021

I’m busy working on Basil, the Small Web host, and while it’s nowhere near ready to use yet, I thought I’d try my hand at writing a database migration as they will be necessary once other people start using it.

Basil runs on Site.js and Site.js uses JSDB – JavaScript Database — as its database.

True to its name, JSDB is 100% JavaScript, so, of course, you write your migrations in JavaScript also.

Here’s what the migration I wrote ended up looking like:¹

// Migration of Settings table from version 1 to version 2.
//
// Payment providers is now an array instead of an object
// and is pre-populated with the defaults for the None and Token
// provider types.
//
// Also, adds the version attribute for the first time, thereby
// enabling future migrations.

const JSDB = require('@small-tech/jsdb')

const db = JSDB.open('.db')
const settings = db.settings

// Is migration necessary?
if (db.settings.version && db.settings.version >= 2) {
  console.log('Already migrated, exiting.')
  process.exit()
}

// Add version to settings table.
settings.version = 2

// Migrate the payment object to an array, copying over
// the Stripe-related details in version 1.
const payment = settings.payment

settings.payment = {
  // Set the payment provider to the new index of the only one
  // that existed previously (Stripe).
  provider: 2,

  // Create the providers array.
  providers: [
    {
      name: 'None',
      modes: null
    },
    {
      name: 'Tokens',
      modes: null,
      codes: []
    },
    {
      name: 'Stripe',
      modes: [ 'test', 'live' ],
      mode: payment.mode,
      modeDetails: payment.modeDetails,
      currency: payment.currency,
      price: payment.price,
      amount: payment.amount
    }
  ]
}

Neither Site.js nor JSDB has any built-in support for migrations yet so this is something you would write into the logic of your own applications at the moment.

As Basil is still under heavy initial development, I just made it a script and ran it directly.

I’m going to keep experimenting with migrations as I work on Basil and I wouldn’t be surprised if they work their way into JSDB and/or Site.js in time.

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The actual migration script has some more code to back up the table and handle errors, etc., but this is the gist of it. ↩︎