module/documents/Actor.mjs

@@ -1,7 +1,7 @@
 import { __ID__ } from "../consts.mjs";
 
 const { Actor } = foundry.documents;
-const { hasProperty } = foundry.utils;
+const { hasProperty, setProperty } = foundry.utils;
 
 export class TAFActor extends Actor {
 
@@ -33,6 +33,12 @@ export class TAFActor extends Actor {
 		super._onEmbeddedDocumentChange(...args);
 		this.#sortedTypes = null;
 	};
+
+	static migrateData(data, ...args) {
+		if (Object.keys(data.system?.attr ?? {}).length > 0) {
+			setProperty(data, `flags.${__ID__}.convertAttributesIntoItems`, true);
+		};
+	};
 	// #endregion Lifecycle
 
 	// #region Token Attributes

module/hooks/ready.mjs

@@ -1,6 +1,10 @@
+import { checkMigrations } from "../migrations/checkMigrations.mjs";
+
 Hooks.on(`ready`, () => {
 	// Remove with issue: Foundry/taf#52
 	if (game.release.generation < 14 && globalThis._loc == null) {
 		globalThis._loc = game.i18n.format.bind(game.i18n);
 	};
+
+	checkMigrations();
 });

module/migrations/checkMigrations.mjs

@@ -0,0 +1,24 @@
+import { __ID__ } from "../consts.mjs";
+import { Logger } from "../utils/Logger.mjs";
+import { migrateTo3_0_0 } from "./v3.0.0.mjs";
+
+const { isNewerVersion } = foundry.utils;
+
+export async function checkMigrations() {
+	if (!game.user.isActiveGM) {
+		Logger.debug(`User not active GM, skipping data migrations`);
+		return;
+	};
+
+	const migrationVersion = game.settings.get(__ID__, `migrationVersion`);
+	let updateVersion = !migrationVersion;
+
+	if (isNewerVersion("3.0.0", migrationVersion)) {
+		await migrateTo3_0_0();
+		updateVersion = true;
+	};
+
+	if (updateVersion) {
+		game.settings.set(__ID__, `migrationVersion`, game.system.version);
+	};
+};

module/migrations/utils.mjs

@@ -0,0 +1,79 @@
+import { __ID__ } from "../consts.mjs";
+
+/**
+ * Migrate the documents within a collection based on what
+ *
+ * This function was originally reproduced from [Draw Steel's codebase](https://github.com/MetaMorphic-Digital/draw-steel/blob/82a0a050da7c0d6d28c0cd283cf3b6915f47ee2a/src/module/data/migrations.mjs#L206-L226),
+ * with modifications to it to work better without
+ *
+ * @param collection The Collection of documents to update.
+ * @param flag The flag name to reference for if the document should be migrated.
+ * @param convertor The function that takes the document and performs the.
+ * transformations to get the required update data.
+ * @param options Options to configure how the method behaves.
+ * @param options.pack The compendium pack to update.
+ * @param options.parent Parent of the collection for embedded collections.
+ * @param options.update Whether or not this method should perform the update, or pass back the array of DB operations.
+ * @returns An array of batch operations to perform.
+ */
+export async function migrateCollection(
+	collection,
+	flag,
+	convertor,
+	options = {}
+) {
+	const toMigrate = collection
+		.filter(doc => {
+			console.log(`toMigrate.filter doc`, doc);
+			return doc.getFlag(__ID__, flag)
+		})
+		.map(doc => {
+			const update = convertor(doc) ?? {};
+			update[`_id`] = doc._id;
+
+			// v13/v14+ compatibility shim
+			if (game.release.generation > 13) {
+				update[`flags.${__ID__}.${flag}`] = _del;
+			} else {
+				update[`flags.${__ID__}.-=${flag}`] = null;
+			};
+
+			return update;
+		})
+		.filter(data => !!data);
+	// update in increments of 100
+	// TODO: optionally return an array of DB operations for modifyBatch
+	const batches = Math.ceil(toMigrate.length / 100);
+	for (let i = 0; i < batches; i++) {
+		const updateData = toMigrate.slice(i * 100, (i + 1) * 100);
+		await collection.documentClass.updateDocuments(
+			updateData,
+			{
+				pack: options.pack,
+				parent: options.parent,
+				diff: false,
+			},
+		);
+	};
+};
+
+/**
+ * Determine whether a compendium pack should be migrated during `migrateWorld`.
+ *
+ * This function was reproduced from [Draw Steel's codebase](https://github.com/MetaMorphic-Digital/draw-steel/blob/82a0a050da7c0d6d28c0cd283cf3b6915f47ee2a/src/module/data/migrations.mjs#L287-L302)
+ *
+ * @param pack The CompendiumPack document
+ * @returns {boolean} Whether or not the pack should be migrated
+ */
+export function shouldMigrateCompendium(pack) {
+	// We only care about actor and item migrations
+	if (!["Actor", "Item"].includes(pack.documentName)) return false;
+
+	// World compendiums should all be migrated, system ones should never by migrated
+	if (pack.metadata.packageType === "world") return true;
+	if (pack.metadata.packageType === "system") return false;
+
+	// Module compendiums should only be migrated if they don't have a download or manifest URL
+	const module = game.modules.get(pack.metadata.packageName);
+	return !module.download && !module.manifest;
+}

module/migrations/v3.0.0.mjs

@@ -0,0 +1,72 @@
+import { Logger } from "../utils/Logger.mjs";
+import { migrateCollection, shouldMigrateCompendium } from "./utils.mjs";
+
+const flag = `convertAttributesIntoItems`;
+const operations = [];
+
+export async function migrateTo3_0_0() {
+	Logger.debug(`Starting v3.0.0 data migration`);
+
+	operations.push(
+		...await migrateCollection(
+			game.actors,
+			flag,
+			handleMigratingActor,
+			{ update: false, },
+		),
+	);
+
+	// for (const pack of game.packs) {
+	// 	if (
+	// 		pack.metadata.type !== "Actor"
+	// 		|| !shouldMigrateCompendium(pack)
+	// 	) {
+	// 		continue;
+	// 	};
+
+	// 	await pack.getDocuments();
+
+	// 	// TODO: unlock compendium if required then re-lock after finishing
+	// 	await migrateCollection(
+	// 		pack,
+	// 		flag,
+	// 		handleMigratingActor,
+	// 		{ pack },
+	// 	);
+	// };
+
+	// TODO: create the item documents (batch them if possible)
+	Logger.debug(`Finished v3.0.0 migration, resulting operations:`);
+	console.log(operations);
+};
+
+function handleMigratingActor(actor) {
+	console.log(actor);
+
+	const operation = {
+		action: `create`,
+		documentName: `Item`,
+		parent: actor,
+		data: [],
+	};
+
+	const attrs = actor.system.attr;
+	for (const [ key, attr ] of Object.entries(attrs)) {
+		operation.data.push(convertToItem(key, attr));
+	};
+	operations.push(operation);
+
+	return null;
+};
+
+function convertToItem(key, attr) {
+	return {
+		name: attr.name,
+		type: "attribute",
+		system: {
+			key,
+			value: attr.value,
+			max: attr.isRange ? attr.max : null,
+		},
+	};
+};

module/settings/world.mjs

@@ -74,4 +74,10 @@ export function registerWorldSettings() {
 		type: Object,
 		scope: `world`,
 	});
+
+	game.settings.register(__ID__, `migrationVersion`, {
+		config: false,
+		type: String,
+		scope: `world`,
+	});
 };