Day 15 Sequence

API Docs:

https://docs.spring.io/spring-data/data-jpa/docs/current/api/
Ref docs:

https://docs.spring.io/spring-data/jpa/docs/current-SNAPSHOT/reference/html/#reference
Spring Java Docs:

Link: https://docs.spring.io/spring-framework/docs/current/javadoc-api/

Solve

List all veg Food Items

Add a method in FoodItemDao extends JpaRepository<FoodItem, Long>:
```
List<FoodItem> findByIsVegTrue();
```

Get restaurant and food items details

Input: Restaurant ID

Add a method in RestaurantDao extends JpaRepository<Restaurant, Long>:

@Query("select r from Restaurant r left join fetch r.foodItems where r.id = :restaurantId")
Optional<Restaurant> getCompleDetails(Long restaurantId);

Update price and description of a food item by its name and restaurant id

Input: Food item name and restaurant ID (unique), new price, and new description

3.1
```
Optional<FoodItem> findByItemNameAndMyRestaurantId(String name, Long restaurantId);
```
3.2 Invoke it from service layer → orElseThrow → call setters → upon service layer method returns → tx.commit → update (DML) → controller.

OR
```
@Query("update FoodItem f set f.price=:pr , f.description=:desc where f.ItemName=:nm and f.myRestaurant.id=:id")
@Modifying
int | long | void updateFoodItemDetails(double pr, String desc, String nm, Long id);
```
Delete product by its name

Input: Product name (unique)

DAO: ProductDao
```
int deleteByName(String nm);
```
List all products having price less than specified price and from specified category (by category name)

DAO: ProductDao
```
List<Product> findByPriceLessThanAndMyCategoryName(double maxPrice, String catName);
```
Apply specified % discount on all products from specified category id, which have not been updated recently

Input: Discount in %, category ID, number of days (not purchased)

In ProductServiceImpl:
- LocalDateTime requiredDateTime = LocalDateTime.now().minusDays(noOfDays);
- Call DAO’s method:
```
@Query("update Product p set p.price=p.price-(p.price*:disc/100) where p.myCategory.id=:catId and p.updatedOn < :oldDateTime")
@Modifying
int applyDiscount(double disc, Long catId, LocalDateTime oldDateTime);
```

1.1 Back end development of full stack application

1.2 Annotations