Cart crud기능 구현

src/main/java/com/campustable/be/domain/cart/controller/CartController.java

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+package com.campustable.be.domain.cart.controller;
+
+
+import com.campustable.be.domain.cart.dto.CartRequest;
+import com.campustable.be.domain.cart.dto.CartResponse;
+import com.campustable.be.domain.cart.service.CartService;
+import com.campustable.be.global.aop.LogMonitoringInvocation;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.DeleteMapping;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/api/cart")
+@RequiredArgsConstructor
+@Slf4j
+public class CartController implements CartControllerDocs{
+
+  private final CartService cartService;
+
+  @LogMonitoringInvocation
+  @Override
+  @PostMapping("/items")
+  public ResponseEntity<CartResponse> addOrUpdateItems(@RequestBody CartRequest request) {
+    CartResponse response = cartService.updateCartItem(request.getMenuId(), request.getQuantity());
+
+    return ResponseEntity.ok(response);
+  }
+
+  @LogMonitoringInvocation
+  @Override
+  @GetMapping("")
+  public ResponseEntity<CartResponse> getCart(){
+
+    CartResponse response = cartService.getCart();
+
+    return ResponseEntity.ok(response);
+  }
+
+
+  @LogMonitoringInvocation
+  @Override
+  @DeleteMapping("/{cartId}")
+  public void deleteCart(@PathVariable Long cartId) {
+    cartService.deleteCart(cartId);
+  }
+
+  @LogMonitoringInvocation
+  @Override
+  @DeleteMapping("/items/{cartItemId}")
+  public void deleteCartItem(@PathVariable Long cartItemId) {
+    cartService.deleteCartItem(cartItemId);
+  }
+}

src/main/java/com/campustable/be/domain/cart/controller/CartControllerDocs.java

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+package com.campustable.be.domain.cart.controller;
+
+import com.campustable.be.domain.cart.dto.CartRequest;
+import com.campustable.be.domain.cart.dto.CartResponse;
+import io.swagger.v3.oas.annotations.Operation;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestBody;
+
+public interface CartControllerDocs {
+
+  @Operation(
+      summary = "장바구니 메뉴 추가 또는 수량 변경",
+      description = """
+          ### 요청 파라미터
+          - `menu_id` (Long, required): 장바구니에 담을 메뉴 ID
+          - `quantity` (int, required): 담을 수량  
+            - 1 이상: 해당 수량으로 장바구니에 추가 또는 수정  
+            - 0: 해당 메뉴를 장바구니에서 삭제
+
+          ### 응답 데이터
+          - `cartId` (Long): 장바구니 ID
+          - `items` (List<CartItemDto>): 장바구니에 담긴 메뉴 목록
+          - `totalPrice` (int): 장바구니 전체 금액
+
+          ### 특징
+          - 수량을 0으로 전달하면 해당 메뉴는 삭제됩니다.
+          - **장바구니가 비워지면 장바구니 엔티티가 자동 삭제**됩니다. (이 경우 응답에 `cartId`가 포함되지 않을 수 있습니다.)
+
+          ### 예외 처리
+          - `MENU_NOT_FOUND` (404): 메뉴 없음
+          - `USER_NOT_FOUND` (404): 유저 없음
+          """
+  )
+  ResponseEntity<CartResponse> addOrUpdateItems(
+      @RequestBody CartRequest request
+  );
+
+  @Operation(
+      summary = "장바구니 조회",
+      description = """
+          ### 특징
+          - JWT 인증 정보로 현재 로그인한 사용자의 장바구니를 조회합니다.
+          - 장바구니가 없는 경우 빈 배열(`[]`)과 `totalPrice: 0`을 반환합니다.
+
+          ### 예외 처리
+          - `USER_NOT_FOUND` (404): 유저 없음
+          - `ACCESS_DENIED` (403): 인증 실패
+          """
+  )
+  ResponseEntity<CartResponse> getCart();
+
+  @Operation(
+      summary = "장바구니 전체 삭제",
+      description = """
+          ### 요청 파라미터
+          - `cartId` (Long): 삭제할 장바구니 ID
+
+          ### 상세 로직
+          - 해당 장바구니 ID가 현재 로그인한 사용자의 것인지 검증합니다.
+          - 사용자와 장바구니의 **연관관계를 명시적으로 끊은 후 삭제**를 진행합니다.
+          - 장바구니 삭제 시 하위의 모든 아이템도 함께 삭제됩니다.
+
+          ### 예외 처리
+          - `CART_NOT_FOUND` (404): 장바구니 없음
+          - `ACCESS_DENIED` (403): **본인의 장바구니가 아닌 경우**
+          """
+  )
+  void deleteCart(@PathVariable Long cartId);
+
+  @Operation(
+      summary = "장바구니 특정 메뉴 삭제",
+      description = """
+          ### 요청 파라미터
+          - `cartItemId` (Long): 삭제할 장바구니 아이템 ID
+
+          ### 상세 로직
+          1. 해당 `cartItemId`가 현재 로그인한 사용자의 장바구니에 속해 있는지 검증합니다.
+          2. 아이템을 삭제한 후, **장바구니에 남은 아이템이 없는지 확인**합니다.
+          3. **남은 아이템이 하나도 없다면 장바구니 엔티티도 함께 삭제** 처리합니다.
+
+          ### 예외 처리
+          - `CART_ITEM_NOT_FOUND` (404): 아이템 없음
+          - `ACCESS_DENIED` (403): **본인의 장바구니 아이템이 아닌 경우**
+          """
+  )
+  void deleteCartItem(@PathVariable Long cartItemId);
+}

src/main/java/com/campustable/be/domain/cart/dto/CartItemDto.java

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+package com.campustable.be.domain.cart.dto;
+
+
+import com.campustable.be.domain.cart.entity.CartItem;
+import lombok.Getter;
+import lombok.Setter;
+
+@Getter
+@Setter
+public class CartItemDto {
+  private String menuName;
+  private int quantity;
+  private int price;
+  private String menuUrl;
+  private Long cartItemId;
+
+  public CartItemDto(CartItem entity) {
+    this.menuName = entity.getMenu().getMenuName();
+    this.price = entity.getMenu().getPrice();
+    this.quantity = entity.getQuantity();
+    this.menuUrl =  entity.getMenu().getMenuUrl();
+    this.cartItemId = entity.getCartItemId();
+  }
+}

src/main/java/com/campustable/be/domain/cart/dto/CartRequest.java

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+package com.campustable.be.domain.cart.dto;
+
+
+import lombok.Getter;
+
+@Getter
+public class CartRequest {
+
+  private Long menuId;
+  private int quantity;
+}

src/main/java/com/campustable/be/domain/cart/dto/CartResponse.java

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+package com.campustable.be.domain.cart.dto;
+
+import java.util.List;
+import lombok.Builder;
+import lombok.Getter;
+import lombok.Setter;
+
+@Getter
+@Setter
+@Builder
+public class CartResponse {
+  private List<CartItemDto> items;
+  private int totalPrice;
+  private Long cartId;
+}

src/main/java/com/campustable/be/domain/cart/entity/Cart.java

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+package com.campustable.be.domain.cart.entity;
+
+import com.campustable.be.domain.user.entity.User;
+import jakarta.persistence.CascadeType;
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import jakarta.persistence.JoinColumn;
+import jakarta.persistence.OneToMany;
+import jakarta.persistence.OneToOne;
+import java.util.ArrayList;
+import java.util.List;
+import lombok.AccessLevel;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+
+@Entity
+@Getter
+@Setter
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
+public class Cart {
+
+  @Id
+  @GeneratedValue(strategy = GenerationType.IDENTITY)
+  @Column(name = "cart_id")
+  private Long cartId;
+
+  @OneToOne
+  @JoinColumn(name = "user_id")
+  private User user;
+
+  @OneToMany(mappedBy = "cart", cascade = CascadeType.ALL, orphanRemoval = true)
+  private List<CartItem> cartItems = new ArrayList<>();
+
+  public Cart(User user) {
+    this.user = user;
+  }
+
+
+}

src/main/java/com/campustable/be/domain/cart/entity/CartItem.java

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+package com.campustable.be.domain.cart.entity;
+
+import com.campustable.be.domain.menu.entity.Menu;
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.FetchType;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import jakarta.persistence.ManyToOne;
+import jakarta.validation.constraints.Min;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+
+@Entity
+@Getter
+@Setter
+@NoArgsConstructor
+public class CartItem {
+
+  public CartItem(Cart cart, Menu menu){
+    this.cart = cart;
+    this.menu = menu;
+  }
+  @Id
+  @GeneratedValue(strategy = GenerationType.IDENTITY)
+  @Column(name= "cart_item_id")
+  private Long cartItemId;
+
+  @ManyToOne(fetch = FetchType.LAZY)
+  private Menu menu;
+
+  @ManyToOne(fetch = FetchType.LAZY)
+  private Cart cart;
+
+  @Min(value = 0, message = "수량은 0 이상이어야 합니다")
+  private int quantity;
+
+
+
+
+}

src/main/java/com/campustable/be/domain/cart/repository/CartItemRepository.java

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+package com.campustable.be.domain.cart.repository;
+
+import com.campustable.be.domain.cart.entity.Cart;
+import com.campustable.be.domain.cart.entity.CartItem;
+import com.campustable.be.domain.menu.entity.Menu;
+import java.util.List;
+import java.util.Optional;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface CartItemRepository extends JpaRepository<CartItem, Long> {
+
+  Optional<CartItem> findByCartAndMenu(Cart cart, Menu menu);
+
+
+  List<CartItem> findByCart(Cart cart);
+
+}

src/main/java/com/campustable/be/domain/cart/repository/CartRepository.java

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+package com.campustable.be.domain.cart.repository;
+
+import com.campustable.be.domain.cart.entity.Cart;
+import com.campustable.be.domain.user.entity.User;
+import java.util.Optional;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface CartRepository extends JpaRepository<Cart, Long> {
+
+  Optional<Cart> findByUser(User user);
+}