Created skeleton class files and updated project structure.

src/main/java/sg/com/smartinventory/controllers/CustomerController.java

@@ -8,6 +8,7 @@
 import org.springframework.web.bind.annotation.RestController;
 
 import jakarta.validation.Valid;
+
 import sg.com.smartinventory.entities.Customer;
 import sg.com.smartinventory.services.CustomerService;
 
@@ -24,7 +25,6 @@ public CustomerController(CustomerService customerService) {
     // CREATE.
     @PostMapping("")
     public ResponseEntity<Customer> createCustomer(@Valid @RequestBody Customer customer) {
-
         // if(bindingResult.hasErrors()) {
         // return new ResponseEntity<>(HttpStatus.BAD_REQUEST);
         // }

src/main/java/sg/com/smartinventory/controllers/ProductController.java

@@ -0,0 +1,34 @@
+package sg.com.smartinventory.controllers;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+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;
+
+import jakarta.validation.Valid;
+import sg.com.smartinventory.entities.Product;
+import sg.com.smartinventory.services.ProductService;
+
+@RestController
+@RequestMapping("/products")
+public class ProductController {
+    private ProductService productService;
+
+    // @Autowired
+    public ProductController(ProductService productService) {
+        this.productService = productService;
+    }
+
+    // CREATE.
+    @PostMapping("")
+    public ResponseEntity<Product> createProduct(@Valid @RequestBody Product product) {
+        // if(bindingResult.hasErrors()) {
+        // return new ResponseEntity<>(HttpStatus.BAD_REQUEST);
+        // }
+
+        Product newProduct = productService.createProduct(product);
+        return new ResponseEntity<>(newProduct, HttpStatus.CREATED);
+    }
+}

src/main/java/sg/com/smartinventory/controllers/ReviewController.java

@@ -0,0 +1,34 @@
+package sg.com.smartinventory.controllers;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+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;
+
+import jakarta.validation.Valid;
+import sg.com.smartinventory.entities.Review;
+import sg.com.smartinventory.services.ReviewService;
+
+@RestController
+@RequestMapping("/reviews")
+public class ReviewController {
+    private ReviewService reviewService;
+
+    // @Autowired
+    public ReviewController(ReviewService reviewService) {
+        this.reviewService = reviewService;
+    }
+
+    // CREATE.
+    @PostMapping("")
+    public ResponseEntity<Review> createReview(@Valid @RequestBody Review review) {
+        // if(bindingResult.hasErrors()) {
+        // return new ResponseEntity<>(HttpStatus.BAD_REQUEST);
+        // }
+
+        Review newReview = reviewService.createReview(review);
+        return new ResponseEntity<>(newReview, HttpStatus.CREATED);
+    }
+}

src/main/java/sg/com/smartinventory/entities/Customer.java

@@ -9,6 +9,7 @@
 import jakarta.validation.constraints.Digits;
 import jakarta.validation.constraints.Email;
 import jakarta.validation.constraints.NotBlank;
+
 import lombok.AllArgsConstructor;
 import lombok.Builder;
 import lombok.Getter;

src/main/java/sg/com/smartinventory/entities/Product.java

@@ -6,6 +6,7 @@
 import jakarta.persistence.GenerationType;
 import jakarta.persistence.Id;
 import jakarta.persistence.Table;
+
 import lombok.AllArgsConstructor;
 import lombok.Builder;
 import lombok.Getter;

src/main/java/sg/com/smartinventory/entities/Review.java

@@ -6,6 +6,7 @@
 import jakarta.persistence.GenerationType;
 import jakarta.persistence.Id;
 import jakarta.persistence.Table;
+
 import lombok.AllArgsConstructor;
 import lombok.Builder;
 import lombok.Getter;

src/main/java/sg/com/smartinventory/exceptions/CustomerNotFoundException.java

@@ -0,0 +1,7 @@
+package sg.com.smartinventory.exceptions;
+
+public class CustomerNotFoundException extends RuntimeException {
+    public CustomerNotFoundException(Long id) {
+        super("Could not find customer with id: " + id + ". ");
+    }
+}

src/main/java/sg/com/smartinventory/exceptions/ProductNotFoundException.java

@@ -0,0 +1,7 @@
+package sg.com.smartinventory.exceptions;
+
+public class ProductNotFoundException extends RuntimeException {
+    public ProductNotFoundException(String id) {
+        super("Could not find product with id: " + id + ". ");
+    }
+}

src/main/java/sg/com/smartinventory/exceptions/ReviewNotFoundException.java

@@ -0,0 +1,7 @@
+package sg.com.smartinventory.exceptions;
+
+public class ReviewNotFoundException extends RuntimeException {
+    public ReviewNotFoundException(String id) {
+        super("Could not find review with id: " + id + ". ");
+    }
+}

src/main/java/sg/com/smartinventory/repositories/CustomerRepository.java

@@ -4,7 +4,7 @@
 
 import sg.com.smartinventory.entities.Customer;
 
-//CustomerRepository simply extends JpaRepository, giving us a lot of default methods to access db without the hardwork  
+// CustomerRepository simply extends JpaRepository, giving us a lot of default methods to access db without the hard work. 
 public interface CustomerRepository extends JpaRepository<Customer, Long> {
 
 }

src/main/java/sg/com/smartinventory/serviceImpls/ProductServiceImpl.java

@@ -0,0 +1,24 @@
+package sg.com.smartinventory.serviceImpls;
+
+import org.springframework.stereotype.Service;
+
+import sg.com.smartinventory.entities.Product;
+import sg.com.smartinventory.repositories.ProductRepository;
+import sg.com.smartinventory.services.ProductService;
+
+@Service
+public class ProductServiceImpl implements ProductService {
+    private ProductRepository productRepository;
+
+    // @Autowired
+    public ProductServiceImpl(ProductRepository productRepository) {
+        this.productRepository = productRepository;
+    }
+
+    @Override
+    public Product createProduct(Product product) {
+        Product newProduct = productRepository.save(product);
+
+        return newProduct;
+    }
+}

src/main/java/sg/com/smartinventory/serviceImpls/ReviewServiceImpl.java

@@ -0,0 +1,24 @@
+package sg.com.smartinventory.serviceImpls;
+
+import org.springframework.stereotype.Service;
+
+import sg.com.smartinventory.entities.Review;
+import sg.com.smartinventory.repositories.ReviewRepository;
+import sg.com.smartinventory.services.ReviewService;
+
+@Service
+public class ReviewServiceImpl implements ReviewService {
+    private ReviewRepository reviewRepository;
+
+    // @Autowired
+    public ReviewServiceImpl(ReviewRepository reviewRepository) {
+        this.reviewRepository = reviewRepository;
+    }
+
+    @Override
+    public Review createReview(Review review) {
+        Review newReview = reviewRepository.save(review);
+
+        return newReview;
+    }
+}

src/main/java/sg/com/smartinventory/services/ProductService.java

@@ -0,0 +1,7 @@
+package sg.com.smartinventory.services;
+
+import sg.com.smartinventory.entities.Product;
+
+public interface ProductService {
+    Product createProduct(Product product);
+}

src/main/java/sg/com/smartinventory/services/ReviewService.java

@@ -0,0 +1,7 @@
+package sg.com.smartinventory.services;
+
+import sg.com.smartinventory.entities.Review;
+
+public interface ReviewService {
+    Review createReview(Review review);
+}

src/main/java/sg/com/smartinventory/utility/DataLoader.java

@@ -0,0 +1,72 @@
+package sg.com.smartinventory.utility;
+
+// import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+
+import jakarta.annotation.PostConstruct;
+
+import sg.com.smartinventory.entities.Customer;
+import sg.com.smartinventory.entities.Product;
+import sg.com.smartinventory.entities.Review;
+import sg.com.smartinventory.repositories.CustomerRepository;
+import sg.com.smartinventory.repositories.ProductRepository;
+import sg.com.smartinventory.repositories.ReviewRepository;
+
+@Component
+public class DataLoader {
+        // Inject all repositories.
+        private CustomerRepository customerRepository;
+        private ProductRepository productRepository;
+        private ReviewRepository reviewRepository;
+
+        // @Autowired
+        public DataLoader(CustomerRepository customerRepository, ProductRepository productRepository,
+                        ReviewRepository reviewRepository) {
+                this.customerRepository = customerRepository;
+                this.productRepository = productRepository;
+                this.reviewRepository = reviewRepository;
+        }
+
+        @PostConstruct
+        public void loadData() {
+                // Clear all data.
+                customerRepository.deleteAll();
+                productRepository.deleteAll();
+                reviewRepository.deleteAll();
+
+                // Create fake data.
+                customerRepository.save(new Customer("John", "Doe", "USA", "123 Main St", 123456, 12345678,
+                                "[email protected]", 101));
+
+                customerRepository.save(new Customer("Alice", "Smith", "Canada", "456 Maple Ave", 543210, 98765432,
+                                "[email protected]", 102));
+                customerRepository.save(new Customer("Michael", "Johnson", "UK", "789 Oak Rd", 567890, 98761234,
+                                "[email protected]", 103));
+                customerRepository.save(new Customer("Emily", "Brown", "Australia", "321 Elm St", 135790, 45678912,
+                                "[email protected]", 104));
+                customerRepository.save(new Customer("David", "Wilson", "Germany", "654 Pine Rd", 987655, 36985214,
+                                "[email protected]", 105));
+
+                productRepository.save(new Product("Electronics", "Smartphone",
+                                "High-end smartphone with advanced features. ", 999.99, 100, 101));
+                productRepository.save(new Product("Clothing", "Men's T-Shirt",
+                                "Comfortable cotton t-shirt for everyday wear. ", 29.99, 500, 102));
+                productRepository.save(new Product("Home & Kitchen", "Coffee Maker",
+                                "Automatic coffee maker with programmable settings. ", 49.99, 50, 103));
+                productRepository.save(new Product("Beauty", "Perfume",
+                                "Elegant fragrance with floral and citrus notes. ", 79.99, 200, 104));
+                productRepository.save(new Product("Books", "Science Fiction Novel",
+                                "Bestselling sci-fi novel set in a dystopian future. ", 14.99, 300, 105));
+
+                reviewRepository.save(new Review("Electronics", "Great smartphone with excellent features. ",
+                                5, 101, 201));
+                reviewRepository.save(new Review("Clothing", "Very comfortable t-shirt, fits perfectly. ",
+                                4, 102, 202));
+                reviewRepository.save(new Review("Home & Kitchen", "Makes delicious coffee, easy to use. ",
+                                4, 103, 203));
+                reviewRepository.save(new Review("Beauty", "Lovely fragrance, long-lasting. ",
+                                5, 104, 204));
+                reviewRepository.save(new Review("Books", "Intriguing plot, couldn't put it down. ",
+                                5, 105, 205));
+        }
+}

src/test/java/sg/com/smartinventory/SmartInventoryApplicationTests.java

@@ -1,6 +1,7 @@
 package sg.com.smartinventory;
 
 import org.junit.jupiter.api.Test;
+
 import org.springframework.boot.test.context.SpringBootTest;
 
 @SpringBootTest

src/test/java/sg/com/smartinventory/CustomerControllerTest.java → src/test/java/sg/com/smartinventory/controllers/CustomerControllerTest.java

@@ -1,9 +1,10 @@
-package sg.com.smartinventory;
+package sg.com.smartinventory.controllers;
 
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;
 
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
+
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
 import org.springframework.boot.test.context.SpringBootTest;