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aral@mastodon.ar.al ("Aral Balkan") wrote:

I haven’t added an example of how you implement migrations with Kitten’s¹ built-in JSDB database² yet but here’s one that I just used when renaming a field (property) in a table (JavaScript object) from “account” to “data” that illustrates the general granular approach you should take within persisted instances of JavaScript classes.

This is, of course, an advanced use case of the built-in JavaScript database that all Kitten apps have.

Kitten is simple for simple use cases. So check out the Persistence tutorial, for example, to see how easy it is to get started with JSDB in Kitten:

https://kitten.small-web.org/tutorials/persistence/

And see the Database App Modules tutorial for a more advanced usage where you persist instances of JavaScript classes and have full type safety:

https://kitten.small-web.org/tutorials/database-app-modules/

¹ https://kitten.small-web.org
² https://codeberg.org/small-tech/jsdb

#Kitten #SmallWeb #SmallTech #web #dev #persistence #JavaScript #database #JavaScriptDatabase #authoring #migrations

Screenshot of code (detail) in Helix Editor on macOS, showing the source for app_modules/database/database.js. The following code is highlighted with a pink border: initialise () { // Migration. if (this.account !== undefined) { this.data = this.account delete this.account } } Full listing texport class VerifiedAccount extends Model { url = this.url || '' /** This is the object returned from the accounts/lookup method of the Mastodon API. See: https://docs.joinmastodon.org/methods/accounts/#lookup @type {{ id: string, username: string, acct: string, display_name: string, locked: boolean, bot: boolean, discoverable: boolean, indexable:boolean, group:boolean, created_at: string, note:string, url: string, uri: string avatar:string avatar_static: string, header: string, header_static: string, followers_count: number, following_count: number, statuses_count: number, last_status_at: string, hide_collections: boolean, noindex: boolean, emojis: Array, roles: Array, fields: Array }} / data = this.data || '' initialise () { // Migration. if (this.account !== undefined) { this.data = this.account delete this.account } } /* The account is the bit of the URL from the @ onwards. */
Screenshot of code for app_modules/database/Model.js. The following code is highlighted with a pink border: /** Optional hook: override this to perform initialisation at constructor time. (Do not override the constructor or the automatic property assignment will fail.) / initialise () {} Full code listing: /* Base model class. (To use, extend this with your own model classes.) When adding properties in subclasses, make sure you only set values after checking if the value already exists: e.g., class MyModelObject extends Model { mySpecialProperty = this.mySpecialProperty || '' } (This way, you will get type safety while authoring without accidentally overwriting any values populated by the superclass when model objects are recreated when a JSDB table is read into memory.) / export default class Model { id = crypto.randomUUID() constructor (parameters = {}) { Object.assign(this, parameters) this.initialise() } /* Optional hook: override this to perform initialisation at constructor time. (Do not override the constructor or the automatic property assignment will fail.) */ initialise () {} }