我正在创建一对多关系，其中类别具有许多产品。在列出所有现有类别之后，我想查看特定类别中的所有产品，并对这些产品（来自该类别）进行基本CRUD。我在Thymealeaf的页面重定向中发现了一些麻烦，最确切的说，我无法使用Thymeleaf来访问“添加产品”页面。
@Entity
@Table(name="category")
public class Category {
@Id
@GeneratedValue(strategy= GenerationType.IDENTITY)
@Column(name="id")
private long id;
@Column
@NotEmpty(message = "*Please provide a description")
private String description;
@OneToMany(mappedBy = "category")
private Set<Product> products;
public Category(){}
@Entity
@Table(name="product")
public class Product {
@Id
@Column(name="id")
private String id;
@Column
private String name;
@Column
private String description;
@Column
private float price;
@Column
private int discount;
@Column
private boolean isInStock;
@ManyToOne
@JoinColumn(name="category_id")
private Category category;
这是我在服务层中保存产品的方式
public Product save(Product product, long id) {
Category category = categoryRepository.getById(id);
if (category != null) {
product.setId(UUID.randomUUID().toString());
product.setCategory(category);
product.setInStock(false);
return productRepository.save(product);
} else {
throw new ResourceNotFoundException("Category not found with id: " + id);
}
}
在控制器中，我有：
@Autowired
ProductService productService;
@GetMapping("/products/{categoryId}")
public String viewProducts(Model model, @PathVariable("categoryId") long categoryId) {
List<Product> productsList = productService.findByCategoryId(categoryId);
model.addAttribute("productsList", productsList);
model.addAttribute("categoryId",categoryId );
return "products";
}
@GetMapping("/newProduct/{categoryId}")
public String showAddForm(Model model,@PathVariable("categoryId") long categoryId) {
Product product = new Product();
model.addAttribute("product", product);
return "newProduct";
}
@PostMapping("/save/{categoryId}")
public String addProduct(@ModelAttribute("product") Product product, @PathVariable long categoryId){
productService.save(product, categoryId);
return "redirect:products";
}
我被困的是，我无法使用路径变量categoryId从products.html重定向到newProduct.html（showAddForm方法应该返回）。它将我重定向到错误页面，如果我手动输入了categoryId URL，我终于到了newProduct.html。在products.html中，我有：
<body>
<div class="container my-2">
<div class="card">
<div class="card-body">
<!-- TODO get category ID from categories (parameters between HTML)-->
<div th:switch="${productsList}" class="container my-5">
<p class="my-5">
<a href="/product/newProduct/" class="btn btn-primary">Add product</a>
</p>
<div class="col-md-10">
<h2 th:case="null">No Products yet!</h2>
<div th:case="*">
<table class="table table-striped table-responsive-md">
<thead>
<tr>
<th>Name</th>
<th>Description</th>
<th>Price</th>
<th>Discount</th>
<th>IsInStock</th>
<th>Edit</th>
<th>Delete</th>
</tr>
</thead>
<tbody>
<tr th:each="product : ${productsList}">
<td th:text="${product.name}"></td>
<td th:text="${product.description}"></td>
<td th:text="${product.discount}"></td>
<td th:text="${product.price}"></td>
<td th:text="${product.isInStock}"></td>
<td><a th:href="@{/product/edit/{id}(id=${product.id})}" class="btn btn-primary"></a></td>
<td><a th:href="@{/product/delete/{id}(id=${product.id})}" class="btn btn-primary"></a></td>
</tr>
</tbody>
</table>
</div>
</div>
</div>
</div>
</div>
</div>
</body>
</html>
我看到的问题是，您的showAddForm路径为@GetMapping("/newProduct/{categoryId}")的代码期望的是catgoryID，该ID在上述“添加产品”按钮中未发送。由于您要在model.addAttribute("categoryId",categoryId );行中传递categoryId，因此可以在href元素中使用它。因此，该链接应类似于
<p class="my-5">
<a th:href="@{/product/newProduct(categoryId=${categoryId})}" class="btn btn-primary">Add product</a>
</p>
但是由于在方法showAddForm中未使用categoryID，因此可以将其删除。并尝试类似
<p class="my-5">
<a th:href="@{/product/newProduct}" class="btn btn-primary">Add product</a>
</p>