Create migration handler

module/systemRegistration/migration-handlers/2_5_2.mjs

@@ -1,7 +1,15 @@
-export class Migration_2_5_2 {
-    version = '2.5.2';
+import { MigrationHandlerBase } from './base.mjs';
 
-    async updateEffect(effectSource, item) {
+export class Migration_2_5_2 extends MigrationHandlerBase {
+    version = '2.5.2';
+    documentNames = ['Actor', 'Item'];
+
+    /** @protected */
+    _preMigrate() {
+
+    }
+
+    async updateEffectSource(effectSource, item) {
         let shouldUpdate = false;
         const newChanges = [];
         const srdItem = item?._stats.compendiumSource ? 

module/systemRegistration/migration-handlers/base.mjs

@@ -0,0 +1,64 @@
+/** 
+ * The base class of an async migration. 
+ * These are generally run between versions for things that require compendiums or must be done in post.
+ * The migrate() functions calls the various updateXSource() functions.
+ * Generally a subclass will override the version and the updateXSource() functions.
+ */
+export class MigrationHandlerBase {
+    version = null;
+
+    async migrate() {
+        // todo: handle migrations, but have a way for a migration handler to specify if migrations are handled
+        // todo: handle more than just migrating effects. Right now this can only migrate effects
+        // NOTE: the preload is hardcoded, we should not hardcode it
+
+        // note: last update costs as 5 on the progress
+        const numActors = game.actors.length;
+        const numItems = game.items.length;
+        const finalUpdateProgress = 5;
+        const DhProgress = game.system.api.applications.ui.DhProgress;
+        const preRunProgress = game.packs.size;
+        
+        const progress = DhProgress.createMigrationProgress(
+            preRunProgress + numActors + numItems + finalUpdateProgress
+        );
+
+        // Preload. Avoid hardcoding in the future
+        for (const pack of game.packs) {
+            await pack.getDocuments();
+            progress.advance();
+        }
+
+        const batch = [];
+
+        const updateItem = async item => {
+            const itemUpdates = [];
+            for (const effect of item.effects) {
+                const changes = await this.updateEffectSource(effect.toObject(), effect.parent);
+                if (changes) itemUpdates.push(changes);
+            }
+            if (itemUpdates.length) {
+                batch.push({
+                    action: 'update',
+                    documentName: 'ActiveEffect',
+                    updates: itemUpdates,
+                    parent: item
+                });
+            }
+        };
+
+        for (const actor of game.actors) {
+            for (const item of actor.items) {
+                await updateItem(item);
+            }
+            progress.advance();
+        }
+        for (const item of game.items) {
+            await updateItem(item);
+            progress.advance();
+        }
+
+        await foundry.documents.modifyBatch(batch);
+        progress.advance({ by: finalUpdateProgress });
+    }
+}

module/systemRegistration/migrations.mjs

@@ -322,42 +322,18 @@ export async function runMigrations() {
         lastMigrationVersion = '2.1.0';
     }
 
-    if (foundry.utils.isNewerVersion('2.5.2', lastMigrationVersion)) {
-        const progress = game.system.api.applications.ui.DhProgress.createMigrationProgress(game.packs.size + 5);
-        for (const pack of game.packs) {
-            await pack.getDocuments();
-            progress.advance();
-        }
-
-        // todo: introduce a runner class that can handle passing on to the different update functions
-        const handler = new Migration_2_5_2();        
-
-        const batch = [];
-        for (const actor of game.actors) {
-            for (const item of actor.items) {
-                const updates = [];
-                for (const effect of item.effects) { 
-                    const update = await handler.updateEffect(effect.toObject(), effect.parent);
-                    if (update) {
-                        updates.push(update);
-                    }
-                }
-
-                if (updates.length) {
-                    batch.push({ item, updates });
-                }
-            }
-        }
-
-        for (const updateData of batch) {
-            await updateData.item.updateEmbeddedDocuments('ActiveEffect', updateData.updates);
-        }
-
-        progress.advance({ by: 5 });
-
-        lastMigrationVersion = '2.5.2';
-    }
-    //#endregion
-
     await game.settings.set(CONFIG.DH.id, CONFIG.DH.SETTINGS.gameSettings.LastMigrationVersion, lastMigrationVersion);
+
+    /* -------------------------------------------- */
+    /*  New Style migrations below this point       */
+    /* -------------------------------------------- */
+
+    const migrations = [
+        new Migration_2_5_2()
+    ].filter(m => m.version && foundry.utils.isNewerVersion(m.version, lastMigrationVersion));
+
+    for (const handler of migrations) {
+        await handler.migrate();
+        await game.settings.set(CONFIG.DH.id, CONFIG.DH.SETTINGS.gameSettings.LastMigrationVersion, handler.version);
+    }
 }