Product Management System

Student Information

• Name: Nguyễn Quang Trực
• Student ID: ITCSIU23041
• Class: Group 2

Technologies Used

• Spring Boot 3.3.x
• Spring Data JPA
• MySQL 8.0
• Thymeleaf
• Maven

Setup Instructions

1. Import project into VS Code
2. Create database: product_management
3. Update application.properties with your MySQL credentials
4. Run: mvn spring-boot:run
5. Open browser: http://localhost:8080/products

Completed Features

• CRUD operations
• Search functionality
• Advanced search with filters
• Validation
• Sorting
• Pagination
• Statistics Dashboard
• REST API (Bonus)

Project Structure

product-management/
│
├── src/
│   ├── main/
│   │   ├── java/
│   │   │   └── com/example/product_management/
│   │   │       ├── ProductManagementApplication.java (Main)
│   │   │       ├── entity/
│   │   │       │   └── Product.java
│   │   │       ├── repository/
│   │   │       │   └── ProductRepository.java
│   │   │       ├── service/
│   │   │       │   ├── ProductService.java
│   │   │       │   └── ProductServiceImpl.java
│   │   │       └── controller/
│   │   │           ├── ProductController.java
│   │   │           └── DashboardController.java 
│   │   │
│   │   └── resources/
│   │       ├── application.properties
│   │       ├── static/
│   │       │   └── css/
│   │       └── templates/
│   │           ├── product-list.html
│   │           ├── product-form.html
│   │           └── dashboard.html        
│   │
│   └── test/
│       └── java/
│
├── pom.xml (Maven dependencies)
└── README.md

Code Flow

1. List Functionality (Read Flow)

Objective: Retrieve and display the complete list of products.

1. Request Initiation: The flow begins when a GET request is made to the root path /products.

2. Controller Layer (ProductController.java): The listProducts method intercepts the request. It calls the service layer to fetch data and adds it to the Model for rendering.

   // Web_lab_7/src/main/java/com/example/product_management/controller/ProductController.java
   @GetMapping
   public String listProducts(Model model) {
       // Retrieve all products from the service layer
       List<Product> products = productService.getAllProducts(); 
       // Bind the list to the model with key "products"
       model.addAttribute("products", products);
       // Return the view name "product-list.html"
       return "product-list";
   }

3. Service Layer (ProductServiceImpl.java): The getAllProducts method delegates the data retrieval to the repository.

   // Web_lab_7/src/main/java/com/example/product_management/service/ProductServiceImpl.java
   @Override
   public List<Product> getAllProducts() {
       // Execute SELECT * FROM products via JPA
       return productRepository.findAll();
   }

4. View Layer (product-list.html): Thymeleaf iterates over the products list to render the table rows.

   <tr th:each="product : ${products}">
       <td th:text="${product.id}">...</td>
       </tr>

---

2. Create Functionality (Create Flow)

Objective: Instantiate and persist a new Product entity.

Phase 1: Form Display (GET)

1. Controller: The showNewForm method maps to /products/new. It creates an empty Product instance to bind form data.

   // Web_lab_7/src/main/java/com/example/product_management/controller/ProductController.java
   @GetMapping("/new")
   public String showNewForm(Model model) {
       // Create empty entity for form binding
       Product product = new Product();
       model.addAttribute("product", product);
       return "product-form";
   }

Phase 2: Data Submission (POST)

1. Controller: The saveProduct method handles the POST request to /products/save.
2. Service & Repository: Since the id of the new product is null, JpaRepository.save() identifies this as an INSERT operation.

   // Web_lab_7/src/main/java/com/example/product_management/service/ProductServiceImpl.java
   @Override
   public Product saveProduct(Product product) {
       // Persist the entity (INSERT if ID is null)
       return productRepository.save(product);
   }

---

3. Update Functionality (Update Flow)

Objective: Modify an existing Product entity. This reuses logic from the Create flow but with a populated ID.

Phase 1: Form Pre-filling (GET)

1. Controller: The showEditForm method accepts the id via the URL path /products/edit/{id}.
2. Service: It attempts to find the existing product.

   // Web_lab_7/src/main/java/com/example/product_management/controller/ProductController.java
   @GetMapping("/edit/{id}")
   public String showEditForm(@PathVariable Long id, Model model, ...) {
       return productService.getProductById(id)
               .map(product -> {
                   // Add existing product to model to pre-fill inputs
                   model.addAttribute("product", product);
                   return "product-form";
               })
               .orElseGet(() -> {
                   // Handle non-existent ID
                   return "redirect:/products";
               });
   }

Phase 2: Data Submission (POST)

1. View: The form includes a hidden input for the ID.

   <input type="hidden" th:field="*{id}" />

2. Controller & Service: The form submits to the same /products/save endpoint. Because the product object now contains a non-null id, the save() method in the repository executes an UPDATE SQL statement instead of an INSERT.

---

4. Delete Functionality (Delete Flow)

Objective: Remove a specific product from the database.

1. Request Initiation: The user clicks "Delete," triggering a GET request to /products/delete/{id}.

2. Controller: The deleteProduct method extracts the id and delegates to the service.

   // Web_lab_7/src/main/java/com/example/product_management/controller/ProductController.java
   @GetMapping("/delete/{id}")
   public String deleteProduct(@PathVariable Long id, RedirectAttributes redirectAttributes) {
       try {
           // Initiate delete operation
           productService.deleteProduct(id);
           // ... (flash message logic)
       } catch (Exception e) {
           // ... (error handling)
       }
       return "redirect:/products";
   }

3. Service Layer: The service method calls the repository's void delete method.

   // Web_lab_7/src/main/java/com/example/product_management/service/ProductServiceImpl.java
   @Override
   public void deleteProduct(Long id) {
       // Execute DELETE FROM products WHERE id = ?
       productRepository.deleteById(id);
   }

---

5. Advanced Search Functionality (Search Flow)

Objective: Filter products based on multiple criteria (Name, Category, Price Range) combined.

1. Request Initiation: The user submits the filter form, sending a GET request to /products/advanced-search with query parameters.

2. Controller: The advancedSearch method captures optional parameters and sanitizes empty strings to null to ensure the repository query logic works correctly.

   // Web_lab_7/src/main/java/com/example/product_management/controller/ProductController.java
   @GetMapping("/advanced-search")
   public String advancedSearch(@RequestParam(required = false) String name, ... ) {
       // Convert empty strings to null for JPA query compatibility
       if (name != null && name.trim().isEmpty()) name = null;
       // ... (call service)
       List<Product> products = productService.advancedSearch(name, category, minPrice, maxPrice);
       model.addAttribute("products", products);
       return "product-list";
   }

3. Repository Layer (ProductRepository.java): A custom JPQL @Query handles the multi-criteria logic using check-for-null idioms (:param IS NULL OR field = :param).

   @Query("SELECT p FROM Product p WHERE " +
          "(:name IS NULL OR p.name LIKE %:name%) AND " +
          "(:category IS NULL OR p.category = :category) AND " +
          "(:minPrice IS NULL OR p.price >= :minPrice) AND " +
          "(:maxPrice IS NULL OR p.price <= :maxPrice)")
   List<Product> searchProducts(@Param("name") String name, ...);

---

6. Validation Functionality

Objective: Ensure data integrity by validating user input before saving to the database.

1. Entity Layer (Product.java): Jakarta Validation annotations are applied to entity fields.

   @NotBlank(message = "Product name is required")
   private String name;
   
   @DecimalMin(value = "0.01", message = "Price must be greater than 0")
   private BigDecimal price;

2. Controller: The saveProduct method uses @Valid to trigger validation and BindingResult to capture errors.

   @PostMapping("/save")
   public String saveProduct(@Valid @ModelAttribute("product") Product product, 
                             BindingResult result, ...) {
       // If validation fails, return to form with error details
       if (result.hasErrors()) {
           return "product-form";
       }
       // Proceed to save
   }

3. View Layer (product-form.html): Thymeleaf displays error messages next to invalid fields.

   <span th:if="${#fields.hasErrors('name')}" th:errors="*{name}" class="error-message">Error</span>

---

7. Sorting Functionality

Objective: Allow users to sort the product list by any column (ID, Name, Price, etc.) in Ascending or Descending order.

1. Request Initiation: Clicking a table header sends a request with sortBy and sortDir parameters (e.g., ?sortBy=price&sortDir=desc).

2. Controller: The listProducts method converts these strings into a Spring Data Sort object.

   // Web_lab_7/src/main/java/com/example/product_management/controller/ProductController.java
   Sort sort = sortDir.equals("asc") ? Sort.by(sortBy).ascending() : Sort.by(sortBy).descending();
   // Pass sort object to service
   List<Product> products = productService.getAllProducts(sort);

3. Service Layer: Passes the Sort object directly to the repository.

   @Override
   public List<Product> getAllProducts(Sort sort) {
       return productRepository.findAll(sort);
   }

---

8. Statistics Dashboard Functionality

Objective: Display high-level metrics (Total Value, Average Price) and alerts (Low Stock).

1. Request Initiation: A GET request is made to /dashboard.

2. Controller (DashboardController.java): Calls specialized service methods to aggregate data.

   @GetMapping
   public String showDashboard(Model model) {
       model.addAttribute("totalValue", productService.getTotalValue());
       model.addAttribute("averagePrice", productService.getAveragePrice());
       model.addAttribute("lowStockProducts", productService.getLowStockProducts(10));
       return "dashboard";
   }

3. Repository Layer: Uses JPQL Aggregate functions (SUM, AVG, COUNT).

   @Query("SELECT COALESCE(SUM(p.price * p.quantity), 0) FROM Product p")
   BigDecimal calculateTotalValue();
   
   @Query("SELECT p FROM Product p WHERE p.quantity < :threshold")
   List<Product> findLowStockProducts(@Param("threshold") int threshold);