Error editing a record using Spring MVC and Thymeleaf

Question

Good colleagues, I am studying Spring through some video lessons and now I have the following problem that I cannot solve I have done everything in my power. The problem is this when I want to click on the link that would supposedly direct me to a page that would allow the change of a record sends the following error in the browser to mention that when I put the path in the url the page opens, the more when I call is that the error is triggered. What should I do?:

Whitelabel Error Page
This application has no explicit mapping for /error, so you are seeing this as a fallback.

Mon Sep 02 17:14:13 CAT 2019
There was an unexpected error (type=Internal Server Error, status=500).
Error resolving template [tarefas/alterar/1], template might not exist or might not be accessible by any of the configured Template Resolvers

below is the view element that calls the edit page:

        <div class="card-footer bg-light">
            <p>
                <a th:href="@{/tarefas/alterar/{id}(id=${tarefa.id})}">Alterar</a>
            </p>
        </div>

below is controller action for the change:

@GetMapping("/alterar/{id}")
    public ModelAndView alterar(@PathVariable Long id) {
        ModelAndView mv = new ModelAndView();
        Tarefa tarefa = rt.getOne(id);
        mv.addObject("tarefa", tarefa);
        return mv;
    }

    @PostMapping("/alterar")
    public ModelAndView alterar(@Valid Tarefa tarefa, BindingResult result) {
        ModelAndView mv = new ModelAndView();
        if (tarefa.getDataExpiracao() == null) {
            result.rejectValue("dataExpiracao", "tarefa.dataExpiracaoInvalida", "A data de expiração obrigatória.");
        } else {
            if (tarefa.getDataExpiracao().before(new Date())) {
                result.rejectValue("dataExpiracao", "tarefa.dataExpiracaoInvalida",
                        "A data de expiração não pode ser anterior à data actual.");
            }
        }
        if (result.hasErrors()) {
            mv.setViewName("tarefas/alterar");
            mv.addObject(tarefa);
        } else {
            mv.setViewName("redirect:/tarefas/listar");
            rt.save(tarefa);
        }
        return mv;
    }

Answer 1

I already solved my problem, I had not put the code snippet that redirected to the page where I would edit. Below I leave the modified action code

@GetMapping("/alterar/{id}")
    public ModelAndView alterar(@PathVariable Long id) {
        ModelAndView mv = new ModelAndView();
        Tarefa tarefa = rt.getOne(id);
        mv.addObject("tarefa", tarefa);
        mv.setViewName("/tarefas/alterar")
        return mv;
    }