feat(services): add getById function to mysql.service

The code now includes a `getById` function in `mysql.service.ts`, which fetches a category by its id. This function will reject with an error message if brandId is not defined or if its length is not 36. The query is executed using a MysqlHandler instance.

Issue: #5
Signed-off-by: Mathis <yidhra@tuta.io>

src/services/mysql.service.ts

@@ -348,6 +348,30 @@ const MySqlService = {
 					reject(err as Error);
 				}
 			})
+		},
+
+		/**
+		 * Fetches a category by its Id
+		 *
+		 * @param {MysqlHandler} handler - The instance of the MysqlHandler used for executing the query
+		 * @param {string} brandId - The Id of the category to be fetched
+		 * @return {Promise<IDbBrand>} - A promise that, when resolved, returns the category matching the Id
+		 * @throws {Error} - If an error occurs during execution
+		 * @throws {string} - If brandId is undefined or invalid
+		 */
+		getById(handler: MysqlHandler, brandId: string): Promise<IDbBrand> {
+			return new Promise((resolve, reject) => {
+				if (!brandId) return reject('slug is undefined')
+				if (brandId.length !== 36) return reject('Id invalid');
+				const _sql = "SELECT * FROM `categories` WHERE `id` = ?";
+				const _values = [brandId];
+				try {
+					resolve(handler.execute(_sql, _values) as unknown as IDbBrand);
+				} catch (err: unknown) {
+					//TODO Reject with null and logger error
+					reject(err as Error);
+				}
+			})
 		}
 	},
 	Model: {