How can I take values from selected checkboxes and send as a List to Spring MVC?

Question

All right? I’m having a doubt, I’m developing a system using Spring MVC and HTML 5 in View,e como renderizador estou utilizando o Thymeleaf.

I’m trying to get all the selected values from a set of checkboxes that represent the days of the week: Monday, Tuesday through Friday and I’d like to know how to get all the values from these selected checkboxes and send as a List to my controller? Below the code of View:

<div class="col-sm-4" >
     <label class="checkbox-inline" th:each="dia : ${todosDiaDaSemana}" >
            <input type="checkbox" th:value="${dia.nome}" th:text="${dia.nome}" name="dias" />
    </label>
</div>

Below follows the Entity Class:

@Entity
@Table(name = "turma")
public class Turma {

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

@Column(length = 80, nullable = false)
private String nome;

@Column(length = 6)
private String horarioInicial;

@Column(length = 6)
private String horarioFinal;

@OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
private List<DiaDaSemana> dias = new ArrayList<>();

@Enumerated(EnumType.STRING)
@Column(length = 15, nullable = false)
private Escolaridade escolaridade;

@Enumerated(EnumType.STRING)
@Column(length = 20, nullable = false)
private Disciplina disciplina;

// methods getters and setters
...
}

Below follows the Entity Diadasemana:

@Entity
@Table(name = "dia_da_semana")
public class DiaDaSemana {

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

@NaturalId
@Column(length = 7, nullable = false)
private String nome;

// methods getters and setters
...
}

Answer 1

Just use the annotation @RequestParam and enter the name of the parameter, which in its case is the field value name in the input type="checkbox".

//Altere o value e method de acordo com o necessário
@RequestMapping(value="caminhoDoMeuFomulario", method=RequestMethod.POST)
public String form(@RequestParam("dias") List<String> dias) {
        //aqui você faz o processamento que quiser
    return "seujsp";
}

In case you want to take better advantage of what Thymeleaf can do, take a look in that integration tutorial between it and Spring MVC. There is a complete example that includes what you want and more!

---

Edit:

In your case it’s not right because you want to link an object to a checkbox. For you to do this, you must implement a org.springframework.core.convert.converter.Converter. Due to the way you mapped your entities, implementing this interface may not be the best option, it would be better to change your mapping a little. I’ll show you both options and you choose the one you think best.

Changing the Map:

As the days of the week are a constant, you could turn them into an enumeration. It would look like this:

Diadasemana

public enum DiaDaSemana {
    DOMINGO("Domingo"),
    SEGUNDA_FEIRA("Segunda-feira"),
    TERCA_FEIRA("Terça-feira"),
    QUARTA_FEIRA("Quarta-feira"),
    QUINTA_FEIRA("Quinta-feira"),
    SEXTA_FEIRA("Sexta-feira"),
    SABADO("Sábado");

    private final String nome;

    private DiaDaSemana(String nome) {
        this.nome = nome;
    }

    public String getNome() {
        return nome;
    }
}

Your class Turma would look like this:

@Entity
@Table(name = "turma")
public class Turma {

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

    @ElementCollection(targetClass=DiaDaSemana.class)
    @CollectionTable(name="turma_diaDaSemana")
    @Enumerated(EnumType.STRING)
    @Column(name="dia", nullable=false)
    private Set<DiaDaSemana> diasDaSemana;

    // Seus outros atributos
    // methods getters and setters
}

Your View(don’t forget to change todosDiasDaSemana for it to reflect the enumeration values. To obtain all the enumeration values just call the method DiaDaSemana.values()):

<div class="col-sm-4" >
    <label class="checkbox-inline" th:each="dia : ${todosDiaDaSemana}" >
        <input type="checkbox" th:value="${dia}" th:text="${dia.nome}" name="diasDaSemana" />
    </label>
</div>

In his Controller:

//Altere o value e method de acordo com o necessário
@RequestMapping(value="caminhoDoMeuFomulario", method=RequestMethod.POST)
public String form(Turma turma) {
        //aqui você faz o processamento que quiser
    return "seujsp";
}

Implementing a Converter:

Diadasemanaconverter:

import org.springframework.core.convert.converter.Converter;

public class DiaDaSemanaConverter implements Converter <String, DiaDaSemana> {

    @Override
       public DiaDaSemana convert(String source) {
        return new DiaDaSemana(source);
    }
}

Register the being DiaDaSemanaConverter in Spring:

@EnableWebMvc
@Configuration
@ComponentSca
public class SpringFrameworkConfig extends WebMvcConfigurerAdapter{

    //Os outros métodos

    @Override
    public void addFormatters(FormatterRegistry registry) {
        registry.addConverter(new DiaDaSemanaConverter());
        super.addFormatters(registry);
    }
}

Your View (the value of the attribute name must be the same as your Setter without the prefix "set", example: if your method is called setDiasDaSemana the attribute name must be diasDaSemana):

<div class="col-sm-4" >
    <label class="checkbox-inline" th:each="dia : ${todosDiaDaSemana}" >
        <input type="checkbox" th:value="${dia.nome}" th:text="${dia.nome}" name="diasDaSemana" />
    </label>
</div>

In his Controller:

//Altere o value e method de acordo com o necessário
@RequestMapping(value="caminhoDoMeuFomulario", method=RequestMethod.POST)
public String form(Turma turma) {
        //aqui você faz o processamento que quiser
    return "seujsp";
}