Prevent the attribute Items from getting invalid keys

module/api.mjs

@@ -5,11 +5,11 @@ import { PlayerSheet } from "./apps/PlayerSheet.mjs";
 import { QueryStatus } from "./apps/QueryStatus.mjs";
 
 // Utils
+import { toID, isValidID, } from "./utils/toID.mjs";
 import { attributeSorter } from "./utils/attributeSort.mjs";
 import { DialogManager } from "./utils/DialogManager.mjs";
 import { localizer } from "./utils/localizer.mjs";
 import { QueryManager } from "./utils/QueryManager.mjs";
-import { toID } from "./utils/toID.mjs";
 
 const { deepFreeze } = foundry.utils;
 
@@ -26,5 +26,6 @@ export const api = deepFreeze({
 		attributeSorter,
 		localizer,
 		toID,
+		isValidID,
 	},
 });

module/data/Item/attribute.mjs

@@ -1,3 +1,7 @@
+import { isValidID, toID } from "../../utils/toID.mjs";
+
+const { hasProperty } = foundry.utils;
+
 export class AttributeItemData extends foundry.abstract.TypeDataModel {
 	// #region Schema
 	static defineSchema() {
@@ -37,6 +41,17 @@ export class AttributeItemData extends foundry.abstract.TypeDataModel {
 
 	// #region Lifecycle
 	async _preCreate(data, options, user) {
+		// Assign the key as the ID'd name if isn't provided, or validate if
+		// it is provided.
+		if (!this.key) {
+			this.updateSource({ key: toID(this.parent.name) });
+		} else if (!isValidID(this.key)) {
+			ui.notifications.error(_loc(
+				`taf.notifs.error.invalid-attribute-key`,
+				{ key: this.key },
+			));
+			return false;
+		};
 
 		// Prevent duplicate Attribute keys from existing on a single Actor
 		if (this.parent.isEmbedded) {
@@ -55,6 +70,19 @@ export class AttributeItemData extends foundry.abstract.TypeDataModel {
 
 		return super._preCreate(data, options, user);
 	};
+
+	async _preUpdate(data, options, user) {
+		// Prevent invalid IDs
+		if (hasProperty(data, `system.key`) && !isValidID(data.system.key)) {
+			ui.notifications.error(_loc(
+				`taf.notifs.error.invalid-attribute-key`,
+				{ key: data.system.key },
+			));
+			delete data.system?.key;
+		};
+
+		return super._preUpdate(data, options, user);
+	};
 	// #endregion Lifecycle
 
 	// #region Methods

module/utils/toID.mjs

@@ -1,6 +1,6 @@
 /**
- * A helper method that converts an arbitrary string into a format that can be
- * used as an object key easily.
+ * A helper method that converts an arbitrary string into a format
+ * that can be used as an object key easily.
  *
  * @param {string} text The text to convert
  * @returns The converted ID
@@ -9,5 +9,26 @@ export function toID(text) {
 	return text
 		.toLowerCase()
 		.replace(/\s+/g, `_`)
-		.replace(/\W/g, ``);
+		.replace(/\W/g, ``)
+		.replace(/(^_|_$)/);
+};
+
+/**
+ * A helper method that reports if an arbitrary string is considered a
+ * valid ID for use in the system
+ *
+ * @param {string} text The text to check
+ * @returns Whether or not the text is a valid ID
+ */
+export function isValidID(text) {
+	return !(
+		// any uppercase characters
+		text.match(/[A-Z]/)
+
+		// any non-word characters
+		|| text.match(/\W/)
+
+		// any whitespace characters
+		|| text.match(/\s/)
+	);
 };