i am getting a bug when i created the product and when it shows the category type it gives me a location for a file - spring

Question

In the createProduct.html after i created the product, and when i go to products.html page which it will show all the products with their details, so i get in the category section a wrong value. as u can see in the page.
Category Entity:
#Entity
public class Categories {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long categories_id;
private String categoryName;
#OneToMany(mappedBy = "product_category",fetch = FetchType.LAZY) //the name of the variable in the other class
private Set<Products> product_category = new HashSet<>();
public Categories(String categoryName, Set<Products> product_category) {
this.categoryName = categoryName;
this.product_category = product_category;
}
public Categories() {
}
public Long getCategories_id() {
return categories_id;
}
public void setCategories_id(Long categories_id) {
this.categories_id = categories_id;
}
public String getCategoryName() {
return categoryName;
}
public void setCategoryName(String categoryName) {
this.categoryName = categoryName;
}
public Set<Products> getProduct_category() {
return product_category;
}
public void setProduct_category(Set<Products> product_category) {
this.product_category = product_category;
}
Products Entity:
#Entity
#Table(name = "Products")
public class Products {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private long product_id;
private String product_name;
private BigDecimal product_price;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "categories_id") //the name of the column in the other class and that name will be a column in the class
private Categories product_category;
private String product_quantity;
private String product_Section;
private String product_ExpDate;
public Products(String product_name, BigDecimal product_price, Categories product_category, String product_quantity, String product_Section, String product_ExpDate) {
this.product_name = product_name;
this.product_price = product_price;
this.product_category = product_category;
this.product_quantity = product_quantity;
this.product_Section = product_Section;
this.product_ExpDate = product_ExpDate;
}
public Products() {
}
public long getProduct_id() {
return product_id;
}
public void setProduct_id(long product_id) {
this.product_id = product_id;
}
public String getProduct_name() {
return product_name;
}
public void setProduct_name(String product_name) {
this.product_name = product_name;
}
public BigDecimal getProduct_price() {
return product_price;
}
public void setProduct_price(BigDecimal product_price) {
this.product_price = product_price;
}
public Categories getProduct_category() {
return product_category;
}
public void setProduct_category(Categories product_category) {
this.product_category = product_category;
}
public String getProduct_quantity() {
return product_quantity;
}
public void setProduct_quantity(String product_quantity) {
this.product_quantity = product_quantity;
}
public String getProduct_Section() {
return product_Section;
}
public void setProduct_Section(String product_Section) {
this.product_Section = product_Section;
}
public String getProduct_ExpDate() {
return product_ExpDate;
}
public void setProduct_ExpDate(String product_ExpDate) {
this.product_ExpDate = product_ExpDate;
}
Product Controller:
#Controller
public class ProductsController {
//adding the service layer of the product
#Autowired
private ProductService productService;
#Autowired
private CategoriesRepository categoriesRepository;
public ProductsController(ProductService productService,CategoriesRepository categoriesRepository )
{
super();
this.productService = productService;
this.categoriesRepository = categoriesRepository;
}
// models
#ModelAttribute("category")
public List<Categories> initializeCategories(){
List<Categories> categories = categoriesRepository.findAll();
return categories ;
}
#ModelAttribute("product")
public Products products()
{
return new Products();
}
/////////////////////////////////// handllers
//request to list all the products
#RequestMapping("/products/all_products")
public String listProducts(Model model)
{
model.addAttribute("product",productService.getAllProducts());
return "Products/products";
}
//request to show the form to create a product // when u are accessing the http request u will access that one coz it will show the form and then the Save method will do the action
#GetMapping("/products/new/product")
public String createProductForm(Model model)
{
//Create product object
Products product = new Products();
model.addAttribute("product",product); // product is the object from products Entityclass
return "Products/create_product";
}
//request to create/save a product
#RequestMapping(value = "/products/create_product",method = RequestMethod.POST)
public String saveProduct(#ModelAttribute("product") Products product) // Products is the name of the Entity class and creating a productObjcet from it
{
productService.saveProduct(product);
return "redirect:/products/all_products";
}
#GetMapping("/products/edit/{id}")
public String editProductForm(#PathVariable long id, Model model)
{
model.addAttribute("product",productService.getProductById(id));
return "Products/edit_product";
}
//request to update product
#RequestMapping(value = "/products/update_product/{id}",method=RequestMethod.POST)
public String updateProduct(#PathVariable Long id, #ModelAttribute("product") Products product, Model model) // model Attribute is the data taken from the html file by the user
{
//get product from the db by id
Products existingProduct = productService.getProductById(id);
existingProduct.setProduct_id(id);
existingProduct.setProduct_name(product.getProduct_name());
existingProduct.setProduct_price(product.getProduct_price());
existingProduct.setProduct_category(product.getProduct_category());
existingProduct.setProduct_quantity(product.getProduct_quantity());
existingProduct.setProduct_Section(product.getProduct_Section());
existingProduct.setProduct_ExpDate(product.getProduct_ExpDate());
//updating the product
productService.updateProduct(existingProduct);
return "redirect:/products/all_products";
}
//request to Delete product
#GetMapping("/products/delete_product/{id}")
public String deleteProduct(#PathVariable long id)
{
productService.deleteProduct(id);
return "redirect:/products/all_products";
}
}
Products.html Page to show all the products
<table class = "table table-striped table-bordered">
<thead class = "table-dark">
<tr>
<th> Category </th>
<th> Product Name </th>
<th> Product Price </th>
<th> Product Quantity </th>
<th> Product Section </th>
<th> Product Expiry Date </th>
<th> Edit </th>
<th> Delete </th>
</tr>
</thead>
<tbody>
<tr th:each = "product: ${product}"> <!-- this attribute to list up products -->
<td th:text="${product.product_category}" ></td>
<td th:text="${product.product_name}"></td>
<td th:text="${product.product_price}"></td>
<td th:text="${product.product_quantity}" ></td>
<td th:text="${product.product_Section}" ></td>
<td th:text="${product.product_ExpDate}" ></td>
<td> <center> <a th:href="#{/products/edit/{id}(id=${product.product_id})}" style="color: green"> Edit </a> </center> </td>
<td> <center> <a th:href="#{/products/delete_product/{id}(id=${product.product_id}) }" style="color: red"> Delete </a> </center> </td>
</tr>
</tbody>
</table>
CreateAProduct.html Page
<form th:action="#{/products/create_product}" method="post" th:object="${product}">
<div class="form-group">
<label class="control-label" for="product_name"> Product Name </label> <input
id="product_name" class="form-control" th:field="*{product_name}"
required autofocus="autofocus" />
</div>
<div class="form-group">
<label class="control-label" for="product_price"> Price </label> <input
id="product_price" class="form-control" th:field="*{product_price}" required
autofocus="autofocus" />
</div>
<div class="col-1.5">
<label th:for="category"> Category </label>
<select class="form-control form-control-sm" id="category" name="product_category">
<option value=""> Select Category </option>
<option th:each = "category: ${category}"
th:value="${category.categories_id}"
th:text="${category.categoryName}"
> <!--th:field="*{product_category}"-->
</option>
</select>
</div>
<br>
<div class="form-group">
<label class="control-label" for="product_quantity"> Quantity </label> <input
id="product_quantity" class="form-control" type="text"
th:field="*{product_quantity}" required autofocus="autofocus" />
</div>
<div class="form-group">
<label class="control-label" for="product_Section"> Section </label> <input
id="product_Section" class="form-control" type="text"
th:field="*{product_Section}" required autofocus="autofocus" />
</div>
<div class="form-group">
<label class="control-label" for="product_ExpDate"> Expire Date </label> <input
id="product_ExpDate" class="form-control" type="text"
th:field="*{product_ExpDate}" required autofocus="autofocus" />
</div>
<div class="form-group">
<button type="submit" class="btn btn-success">Save</button>
</div>
</form>
Product Service layer:
#Service
public class ProductServiceImp implements ProductService {
//productRepository class
private ProductRepository productRepository;
public ProductServiceImp(ProductRepository productRepository) {
this.productRepository = productRepository;
}
#Override
public List<Products> getAllProducts() {
return this.productRepository.findAll();
}
#Override
public Products saveProduct(Products product) {
return this.productRepository.save(product);
}
#Override
public Products updateProduct(Products product) {
return this.productRepository.save(product);
}
#Override
public void deleteProduct(long id) {
this.productRepository.deleteById(id);
}
public Products getProductById(long id)
{
return productRepository.findById(id).get();
}
}

Answer 1

The Categories class is which is being used to display the value under that Category Column you see in HTML.
You either override toString():
#Entity
public class Categories {
...
...
#Override
public String toString() {
return categoryName;
}
}
Or you call the categoryName directly instead of the Object (product_category) itself:
<td th:text="${product.product_category.categoryName}" ></td>