Null value passed from drop-down list-CodePudding

I am creating a Spring Boot application with thymeleaf where I have an relationship Many-to-One between a table named figures and a table named states (many figures to one state). Everything is OK when creating a state. The problem is with creating a figure. These are the classes:

@Entity
@Table(name = "state")
public class State implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id_state")
private Integer idState;

@Column(name = "official_state_name")
private String officialStateName;

@Column(name = "official_language")
private String officialLanguage;

@Column(name = "state_currency")
private String stateCurrency; 

//setters and getters


@Entity
@Table(name = "figure")
public class Figure implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id_figure")
private Long idFigure;

@Column(name = "pib")
private String fullName;

@Column(name = "date_of_birth")
private java.sql.Date dateOfBirth;

@Column(name = "date_of_death", nullable = true)
private java.sql.Date dateOfDeath;

@Column(name = "kind_of_activity")
private String kindOfActivity;

@ManyToOne(fetch = FetchType.LAZY, optional = false)
@JoinColumn(name = "id_state", nullable = false)
private State state;

public State getState() {
    return state;
}

public void setState(State state) {
    this.state = state;
}

public Long getIdFigure() {
    return this.idFigure;
}

public void setIdFigure(Long idFigure) {
    this.idFigure = idFigure;
}

public String getFullName() {
    return this.fullName;
}

public void setFullName(String pib) {
    this.fullName = fullName;
}

public java.sql.Date getDateOfBirth() {
    return this.dateOfBirth;
}

public void setDateOfBirth(java.sql.Date dateOfBirth) {
    this.dateOfBirth = dateOfBirth;
}

public java.sql.Date getDateOfDeath() {
    return this.dateOfDeath;
}

public void setDateOfDeath(java.sql.Date dateOfDeath) {
    this.dateOfDeath = dateOfDeath;
}

public String getKindOfActivity() {
    return this.kindOfActivity;
}

public void setKindOfActivity(String kindOfActivity) {
    this.kindOfActivity = kindOfActivity;
}

}

Now this is the controller for the Figure class:

@Controller
public class FigureController {


@Autowired
FigureService figureService;

@Autowired
FigureRepository figureRepository;

@Autowired
StateRepository stateRepository;
@Autowired
StateService stateService;

@GetMapping("/figures")
public String showAllFigures(Model model){
    List<Figure> listFigures = figureService.findAllFigures();
    model.addAttribute("listFigures", listFigures);
    return "figures";
}

@GetMapping("/figures/new")
public String showNewFigureForm(Model model){
    List <State>  listStates = stateService.findAll();
    model.addAttribute("listStates", listStates);
    model.addAttribute("figure", new Figure());
    model.addAttribute("pageTitleF", "Add New Figure");
    return "figure_form";
}

@PostMapping("/figures/save")
public String saveFigure (Figure requestFigure, RedirectAttributes redirectAttributes) throws StateNotFoundException {
    figureRepository.save(requestFigure);
    redirectAttributes.addFlashAttribute("messageF", "The figure has been saved successfully!");
    return "redirect:/figures";
}

@GetMapping("/figures/edit/{id}")
public String showEditFigureForm(@PathVariable("id") Integer id, Model model, RedirectAttributes redirectAttributes){
    try {
        Figure figure = figureService.findFigureById(id);
        List <State>  listStates = stateService.findAll();
        model.addAttribute("listStates", listStates);
        model.addAttribute("figure", figure);
        model.addAttribute("pageTitleF", "Edit Figure (ID: "   id   ")");
        return "figure_form";
    } catch (EntityNotFoundException e) {
        redirectAttributes.addFlashAttribute("messageF", e.getMessage());
        return "redirect:/figures";
    }
}

@GetMapping("/figures/delete/{id}")
public String deleteFigure(@PathVariable("id") Integer id, Model model, RedirectAttributes redirectAttributes){
    try {
        figureService.deleteFigure(id);
        redirectAttributes.addFlashAttribute("messageF", "The figure ID "   id   " has been deleted!");
    } catch (StateNotFoundException e) {
        redirectAttributes.addFlashAttribute("messageF", e.getMessage());
    }
    return "redirect:/figures";
}

}

So I need to pass an id of state from drop-down list of states and assign it to the foreign key of the figure entity. These are the html files. figures.html

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>Welcome to My Application</title>
    <link rel="stylesheet" type="text/css" th:href="@{/webjars/bootstrap/css/bootstrap.min.css}"/>
</head>
<body>
<div >
    <div><h2>Manage Figures</h2></div>
    <div >
        <a  th:href="@{/figures/new}">Add New Figure</a>
    </div>
    <div >
        <a  th:href="@{http://localhost:8080/}">Back to Main Menu</a>
    </div>
    <div th:if="${messageF}" >
        [[${messageF}]]
    </div>
    <div>
        <table >
            <thead >
            <tr>
                <th>ID</th>
                <th>Full Name</th>
                <th>Date of Birth</th>
                <th>Date of Death</th>
                <th>kindOfActivity</th>
                <th></th>
            </tr>
            </thead>
            <tbody>
            <th:block th:each="figure : ${listFigures}">
                <tr>
                    <td>[[${figure.fullName}]]</td>
                    <td>[[${figure.dateOfBirth}]]</td>
                    <td>[[${figure.dateOfDeath}]]</td>
                    <td>[[${figure.kindOfActivity}]]</td>
                    <td>
                        <a  th:href="@{'/figures/edit/'  ${figure.idFigure}}">Edit</a>
                        <a  th:href="@{'/figures/delete/'  ${figure.idFigure}}">Delete</a>
                    </td>
                </tr>
            </th:block>
            </tbody>
        </table>
    </div>
</div>
</body>
</html>

figure_form.html

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>[[${pageTitleF}]]</title>
    <link rel="stylesheet" type="text/css" th:href="@{/webjars/bootstrap/css/bootstrap.min.css}"/>
</head>
<body>
<div >
    <div ><h2>[[${pageTitleF}]]</h2></div>

    <form th:action="@{/figures/save}" method="post" th:object="${figure}"
          style="max-width: 500px; margin: 0 auto;">
        <input type="hidden" th:field="*{idFigure}">
        <div >
            <div >
                <label >Full Name</label>
                <div >
                    <input type="text" th:field="*{fullName}"  required minlength="4" maxlength="40"/>
                </div>
            </div>
            <div >
                <label >Date of Birth</label>
                <div >
                    <input type="date" th:field="*{dateOfBirth}"  />
                </div>
            </div>
            <div >
                <label >Date of Death</label>
                <div >
                    <input type="date" th:field="*{dateOfDeath}"  />
                </div>
            </div>
            <div >
                <label >Kind of Activity</label>
                <div >
                    <input type="text" th:field="*{kindOfActivity}"  required maxlength="60"/>
                </div>
            </div>
            <div >
            <label >State</label>
            <div >
                <select  id="idState" name="idState">
                    <option value="">Select State</option>
                    <option th:each="state : ${listStates}"
                            th:value="${state.idState}"
                            th:text="${state.idState} ' : ' ${state.officialStateName}"></option>
                </select>
            </div>
        </div>

            <div >
                <button type="submit" >Save</button>
                <button type="button"  onclick="cancelForm()">Cancel</button>
            </div>
        </div>

    </form>

</div>
<script type="text/javascript">
    function cancelForm(){
        window.location = "[[@{/figures}]]"
    }
</script>
</body>
</html>

So the form looks like this:

When I hit the save button I get an error status 500:

And the error description

org.hibernate.PropertyValueException: not-null property references a null or transient value : com.historicalreferencebook.historicalreferencebook.domain.Figure.state

As you can see even though I chose a state and therefore its key is assigned to the foreign key of the figure entity, it is null. Why? And what should I do to pass the value from the drop down list to the foreign key of the figure? Any help is appreciated! Thanks in advance!

CodePudding user response：

@ManyToOne(fetch = FetchType.LAZY, optional = false)
@JoinColumn(name = "id_state", nullable = false)
private State state;

change to:

@ManyToOne(fetch = FetchType.LAZY,
       optional = false,
       cascade = {CascadeType.PERSIST, CascadeType.MERGE})
@JoinColumn(name = "id_state", nullable = false)
private State state;

CodePudding user response：

I got it sovled dropping a table and then creating it once again with maven installation, i changed id data type to Integer and used this as a drop down list (because there is a "th:field" which tells the spring which field will be filled with value from a drop down list):

            <div >
                <label >State</label>
                <div >
                    <select th:field="*{state}"  required>
                        <th:block th:each="state : ${listStates}">
                            <option th:text="${state.officialStateName}" th:value="${state.idState}"/>
                        </th:block>
                    </select>
                </div>
            </div>