How to fix these and other errors: Failed to Convert from type [java.lang.String] to type [java.lang.Long] for value 'list'?

Question

I’m implementing an example of a book about Spring Boot, but, after executing, while trying to access the route /clientes/list or else, /clientes/view in the browser appear the following errors:

Failed to Convert value of type 'java.lang.String' to required type 'com.greendog.models.Client'; nested Exception is org.springframework.core.convert.Conversionfailedexception: Failed to Convert from type [java.lang.String] to type [java.lang.Long] for value 'list'; nested Exception is java.lang.Numberformatexception: For input string: "list"

I don’t know how to fix it. Follow my codes:

Class Cliente.java:

package com.greendog.modelos;

import java.util.ArrayList;
import java.util.List;

import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.validation.constraints.NotNull;

import org.hibernate.annotations.Cascade;
import org.hibernate.annotations.CascadeType;
import org.hibernate.validator.constraints.Length;

import com.greendog.modelos.Pedido;

@Entity
public class Cliente {

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Long id;

    @NotNull
    @Length(min=2, max=30, message="O tamanho do nome deve ser entre {min} e {max} caracteres.")
    private String nome;

    @NotNull
    @Length(min=2, max=300, message="O tamanho do endereçomdeve ser entre {min} e {max} caracteres.")
    private String endereco;

    @OneToMany(mappedBy = "cliente", fetch = FetchType.EAGER)
    @Cascade(CascadeType.ALL)
    private List<Pedido> pedidos;


    public Cliente(Long id, String nome, String endereco) {
        this.id = id;
        this.nome = nome;
        this.endereco = endereco;
    }

    public void novoPedido(Pedido pedido) {
        if(this.pedidos == null) pedidos = new ArrayList<Pedido>();
        pedidos.add(pedido);

    }
     /*Getter e Setter */
}

Interface ClienteRepository.java:

package com.greendog.repositories;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

import com.greendog.modelos.Cliente;

@Repository
public interface ClienteRepository extends JpaRepository<Cliente, Long>{

}

Class ClienteController.java:

package com.greendog.controladores;

import javax.validation.Valid;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.support.RedirectAttributes;

import com.greendog.modelos.Cliente;
import com.greendog.repositories.ClienteRepository;

@Controller
@RequestMapping("/clientes")
public class ClienteController {

    @Autowired
    private final ClienteRepository clienteRepository = null;

    //Exibe as lista de Clientes
    @GetMapping("/")
    public ModelAndView list() {
        Iterable<Cliente> clientes = this.clienteRepository.findAll();
        return new ModelAndView("clientes/list", "clientes", clientes);
    }

    //Exibe o detalhe de cada cliente
    @GetMapping("{id}")
    public ModelAndView view(@PathVariable("id") Cliente cliente) {
        return new ModelAndView("clientes/view", "cliente", cliente);
    }

    //Direciona para criar novo cliente
    @GetMapping("/novo")
    public String createForm(@ModelAttribute Cliente cliente) {
        return "clientes/form";
    }

    //Insere novo cliente através de um formulario
    @PostMapping(params = "form")
    public ModelAndView create(@Valid Cliente cliente, BindingResult result, RedirectAttributes redirect) {
        if(result.hasErrors()){
            return new ModelAndView("clientes/" + "form", "formErros", result.getAllErrors());
        }

        cliente = this.clienteRepository.save(cliente);
        redirect.addFlashAttribute("globalMessage", "Cliente gravado com sucesso!");

        return new ModelAndView("redirect:/" + "clientes/" + "{cliente.id}", "cliente.id", cliente.getId());
    }

    //Atualizar cliente
    @GetMapping(value = "alterar/id")
    public ModelAndView alterarForm(@PathVariable("id") Cliente cliente) {
        return new ModelAndView("cliente/form", "cliente", cliente);
    }

    //Remover Cliente
    public ModelAndView remover(@PathVariable("id") Long id, RedirectAttributes redirect) {
        this.clienteRepository.deleteById(id);
        Iterable<Cliente> clientes = this.clienteRepository.findAll();
        ModelAndView mv = new ModelAndView("clientes/list","clientes", clientes);
        mv.addObject("globalMessage", "Cliente removido com sucesso!");
        return mv;
    }
}

My folder structure of this project:

Complete code on Github.

Answer 1

it is falling into this exception because you are incorrectly calling your endpoint, when you call the path /clients/list in fact you are passing the string "list" to your view method, which causes your exception, the right would be customers/15 for example, being 15 the id of your customer, or just customers to call the list method

---

editing the answer here because I realized that there are several mistakes seeing your git 1° Your controllers methods, realize that you are using the Modelandview method passing in the constructor the name of the view, the name of the model and then the object of the model, your model is called client and the time to pass you ta passing clients plural in some calls, It needs to be the same because otherwise he won’t identify it. 2° your view method you are getting a model but put the id name, I think you got confused here, in my view you should exchange this Client for long id 3° still in your view method, you are passing the client with nothing, la na front will give an exception for null, changing your method he was like this for me:

@GetMapping("{id}")
    public ModelAndView view(@PathVariable("id") long id) {
        Cliente cliente = new Cliente(id, "Lucas", "123456"); //essa parte aqui você deve trocar pelo seu select
        return new ModelAndView("view", "cliente", cliente);
    }

4° in your html you put in the view that is giving error on line 10 th:if="{globalMessage}", there’s a dollar missing here and that’s why the parsing was wrong, the right one would be th:if="${globalMessage}"