feat(services): update category service functions

Update category service functions with added getBySlug function and refactor getAllCategory to getAll. Exception handling has been improved, returning null on error.

Issue: #11
Signed-off-by: Mathis <yidhra@tuta.io>

src/services/category.service.ts

@@ -30,18 +30,31 @@ async function createCategory(data: IDbCategory): Promise<unknown> {
 	}
 }
 
-//FEAT Get all categories
-async function getAllCategory() {
+/**
+ * Retrieves all categories from the database.
+ *
+ * @returns {Promise<Array<IDbCategory>> | null} Promise that resolves to an array of IDbCategory objects or null if an error occurred.
+ */
+async function getAll(): Promise<Promise<Array<IDbCategory>> | null> {
 	try {
 			logger.info("Getting all categories...");
       return await MysqlService.Category.getAll(DbHandler);
   } catch (error) {
       logger.error(`Error getting all categories: ${error}`);
-      return;
+      return null;
   }
 }
 
 //FEAT Get a category (slug)
+async function getBySlug(slug: string) {
+	try {
+    logger.info(`Getting category by slug... (${slug})`);
+    return await MysqlService.Category.getBySlug(DbHandler, slug);
+  } catch (error) {
+    logger.error(`Error getting category by slug: ${error}`);
+    return null;
+  }
+}
 
 //FEAT Get a category (id)
 
@@ -51,7 +64,8 @@ async function getAllCategory() {
 
 const CategoryService = {
 	create: createCategory,
-	getAll: getAllCategory
+	getAll,
+	getBySlug
 }
 
 export default CategoryService;