fix(cart): clear cart after successful payment and preserve coupon on checkout

- Add ClearCart API endpoint to remove all cart items by userId
- Call ClearCartAsync in Confirmation page after payment approved
- Add CouponCode hidden field in CheckOut.cshtml for clarity

Fixes:
1. Cart items not being removed after successful payment
2. Coupon code display consistency in checkout flow

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: ledai091

Cherry.Services.ShoppingCartAPI/Controllers/CartAPIController.cs

@@ -190,10 +190,41 @@ public async Task<ResponseDto> RemoveCart([FromBody]int cartDetailsId)
                 if(totalCountofCartItem == 1)
                 {
                     var cartHeaderToRemove=await _db.CartHeaders.FirstOrDefaultAsync(
-                        u=>u.CartHeaderId==cartDetails.CartHeaderId);   
+                        u=>u.CartHeaderId==cartDetails.CartHeaderId);
                     _db.CartHeaders.Remove(cartHeaderToRemove);
                 }
-                await _db.SaveChangesAsync();   
+                await _db.SaveChangesAsync();
+                _response.Result = true;
+            }
+            catch (Exception ex)
+            {
+                _response.Message = ex.Message.ToString();
+                _response.IsSuccess = false;
+            }
+            return _response;
+        }
+
+        [HttpDelete("ClearCart/{userId}")]
+        public async Task<ResponseDto> ClearCart(string userId)
+        {
+            try
+            {
+                var cartHeader = await _db.CartHeaders
+                    .FirstOrDefaultAsync(u => u.UserId == userId);
+
+                if (cartHeader != null)
+                {
+                    // Remove all cart details associated with this cart header
+                    var cartDetails = _db.CartDetails
+                        .Where(u => u.CartHeaderId == cartHeader.CartHeaderId);
+                    _db.CartDetails.RemoveRange(cartDetails);
+
+                    // Remove the cart header
+                    _db.CartHeaders.Remove(cartHeader);
+
+                    await _db.SaveChangesAsync();
+                }
+
                 _response.Result = true;
             }
             catch (Exception ex)

Cherry.Web/Controllers/CartController.cs

@@ -97,6 +97,12 @@ public async Task<IActionResult> Confirmation(int orderId)
                 OrderHeaderDto orderHeader = JsonConvert.DeserializeObject<OrderHeaderDto>(Convert.ToString(response.Result));
                 if(orderHeader.Status == SD.Status_Approved)
                 {
+                    // Clear the cart after successful payment
+                    var userId = User.Claims.Where(u => u.Type == JwtRegisteredClaimNames.Sub)?.FirstOrDefault()?.Value;
+                    if (!string.IsNullOrEmpty(userId))
+                    {
+                        await _cartService.ClearCartAsync(userId);
+                    }
                     return View(orderId);
                 }
             }

Cherry.Web/Service/CartService.cs

@@ -59,5 +59,14 @@ public CartService(IBaseService baseService)
                 Url = SD.ShoppingCartAPIBase + "/api/cart/CartUpsert"
             });
         }
+
+        public async Task<ResponseDto?> ClearCartAsync(string userId)
+        {
+            return await _baseService.SendAsync(new RequestDto()
+            {
+                ApiType = SD.ApiType.DELETE,
+                Url = SD.ShoppingCartAPIBase + "/api/cart/ClearCart/" + userId
+            });
+        }
     }
 }

Cherry.Web/Service/IService/ICartService.cs

@@ -9,5 +9,6 @@ public interface ICartService
         Task<ResponseDto?> RemoveFromCartAsync(int cartDetailsId);
         Task<ResponseDto?> ApplyCouponAsync(CartDto cartDto);
         Task<ResponseDto?> EmailCart(CartDto cartDto);
+        Task<ResponseDto?> ClearCartAsync(string userId);
     }
 }

Cherry.Web/Views/Cart/CheckOut.cshtml

@@ -5,6 +5,7 @@
     {
         <input asp-for="CartHeader.UserId" hidden />
         <input asp-for="CartHeader.CartHeaderId" hidden />
+        <input asp-for="CartHeader.CouponCode" hidden />
         <input asp-for="CartHeader.Discount" hidden />
         <input asp-for="CartHeader.CartTotal" hidden />
     }