Delete tag when the last note using it is deleted

src/lib/db/migrations/2023-09-30.ts

@@ -0,0 +1,21 @@
+import type { Kysely, Migration } from 'kysely';
+import { sql } from 'kysely';
+
+export const Migration20230930: Migration = {
+	async up(db: Kysely<any>) {
+		await db
+			.deleteFrom('tag')
+			.where('id', 'not in', ({ selectFrom }: any) => selectFrom('noteTag').select('tagId'))
+			.execute();
+
+		await sql`
+      CREATE TRIGGER noteTagDeleteUnusedTagTrigger AFTER DELETE ON noteTag
+      BEGIN
+        DELETE FROM tag WHERE id = old.tagId AND (SELECT COUNT(*) FROM noteTag WHERE tagId = old.tagId) = 0;
+      END;
+    `.execute(db);
+	},
+	async down(db: Kysely<any>) {
+		await sql`DROP TRIGGER noteTagDeleteUnusedTagTrigger`.execute(db);
+	},
+};

src/lib/db/migrations/index.ts

@@ -1,6 +1,8 @@
 import type { Migration } from 'kysely';
 import { Migration20230830 } from './2023-08-30';
+import { Migration20230930 } from './2023-09-30';
 
 export const migrations: Record<string, Migration> = {
 	'2023-08-30': Migration20230830,
+	'2023-09-30': Migration20230930,
 };

src/lib/stores/note-tags.ts

@@ -54,28 +54,18 @@ export class NoteTagsStore implements Readable<Tag[]> {
 	};
 
 	remove = async (tagId: Tag['id']) => {
-		const noteId = this.noteId;
-
-		await db.transaction().execute(async (trx) => {
-			await trx
+		const [deletedNoteTag] = await db
 			.deleteFrom('noteTag')
-				.where('noteId', '=', noteId)
+			.where('noteId', '=', this.noteId)
 			.where('tagId', '=', tagId)
-				.executeTakeFirstOrThrow();
-			const remainingTagUsage = await trx
-				.selectFrom('noteTag')
-				.where('tagId', '=', tagId)
-				.select('tagId')
-				.executeTakeFirst();
-
-			if (!remainingTagUsage) {
-				await trx.deleteFrom('tag').where('id', '=', tagId).executeTakeFirstOrThrow();
-			}
-		});
+			.returningAll()
+			.execute();
 
 		this.refreshTags();
 		this.notes.refreshNotes();
 		this.tags.refreshTags();
+
+		return deletedNoteTag;
 	};
 
 	search = async (searchString: string): Promise<string[]> => {