Refactor: Introduce requiredString helper for consistent validation across routes and services

src/routes/user.routes.ts

@@ -33,6 +33,9 @@ const validatePasswordStrength = (password: string): { isValid: boolean; feedbac
   return { isValid: true };
 };
 
+// Helper for consistent required string validation (handles missing/null/empty)
+const requiredString = (message: string) => z.preprocess((val) => val ?? '', z.string().min(1, message));
+
 // --- Zod Schemas for User Routes (as per ADR-003) ---
 
 const numericIdParam = (key: string) => z.object({
@@ -54,17 +57,17 @@ const updatePasswordSchema = z.object({
 });
 
 const deleteAccountSchema = z.object({
-  body: z.object({ password: z.string().min(1, "Field 'password' is required.") }),
+  body: z.object({ password: requiredString("Field 'password' is required.") }),
 });
 
 const addWatchedItemSchema = z.object({
   body: z.object({
-    itemName: z.string().min(1, "Field 'itemName' is required."),
-    category: z.string().min(1, "Field 'category' is required."),
+    itemName: requiredString("Field 'itemName' is required."),
+    category: requiredString("Field 'category' is required."),
   }),
 });
 
-const createShoppingListSchema = z.object({ body: z.object({ name: z.string().min(1, "Field 'name' is required.") }) });
+const createShoppingListSchema = z.object({ body: z.object({ name: requiredString("Field 'name' is required.") }) });
 
 // Apply the JWT authentication middleware to all routes in this file.
 const notificationQuerySchema = z.object({
@@ -417,7 +420,7 @@ router.delete('/shopping-lists/:listId', validateRequest(shoppingListIdSchema),
 const addShoppingListItemSchema = shoppingListIdSchema.extend({
   body: z.object({
     masterItemId: z.number().int().positive().optional(),
-    customItemName: z.string().min(1).optional(),
+    customItemName: requiredString('customItemName required?'),
   }).refine(data => data.masterItemId || data.customItemName, { message: 'Either masterItemId or customItemName must be provided.' }),
 });
 type AddShoppingListItemRequest = z.infer<typeof addShoppingListItemSchema>;