I can't get redirected to my update page in Spring Boot 3 using Thymeleaf

I get this error:

An error happened during template parsing (template: "class path resource [templates/update-customer.html]")
org.thymeleaf.exceptions.TemplateInputException: An error happened during template parsing (template: "class path resource [templates/update-customer.html]")

I can not be redirected to my update-customer.html because of this problem.

list.html:

  <td>
     <a th:href="@{'/customers/form-update-customer/' + ${customer.id}}" class="btn btn-primary btn-sm">Update</a>
  </td>

CustomerController.java:

@Controller
@RequestMapping("/customers")
public class CustomerController {

  private CustomerService customerService;

  public CustomerController(CustomerService theCustomerService){
        customerService = theCustomerService;
  }

  @GetMapping("/form-update-customer/{id}")
    public String formUpdateCustomer(@PathVariable("id") int id, Model model) {
      CustomerModel customerModel = customerService.read(id);
      model.addAttribute("customer", customerModel);
      return "update-customer";
  }

}

update-customer.html


    <!doctype html>
    <html lang="en" xmlns:th="http://thymeleaf.org">
    <head>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
        <link rel="stylesheet" th:href="@{/assets/bootstrap-5.3.3.min.css}">
        <script th:src="@{/assets/bootstrap-5.3.3.min.js}"></script>
        <script th:src="@{/assets/jquery-3.7.1.min.js}"></script>
        <script th:src="@{/assets/mask.js}"></script>
        <meta http-equiv="X-UA-Compatible" content="ie=edge">
        <title>Update Customer</title>
    </head>
    <body>
    <form th:action="@{'/customers/update-customer/' + *{id}}" method="POST">
        <input type="hidden" th:field="*{id}">
        <input type="text" th:field="*{name}" class="form-control mb-4 w-25" placeholder="Input the name"/>
        <div th:if="${#fields.hasErrors('name')}" th:errors="*{name}" class="text-danger"></div>
        <button type="submit" class="btn btn-info col-2">Update</button>
    </form>
    </body>
    </html>

I guess that Update button is right, return me localhost:8080/customers/form-update-customer/8.

Solution

The form tag in update-customer.html should be either:

<form th:action="@{'/customers/update-customer/' + ${customer.id}}"
    th:object="${customer}" method="POST">

<form th:action="@{/customers/update-customer/{id}(id = ${customer.id})}"
    th:object="${customer}" method="POST">

Both are valid. The crucial point is th:object="${customer}" where you bind the model variable customer, added in the controller, to the form data object model (DOM). After doing it, you can access the object properties like this:

${customer.id}

*{name}