从具有 1:N 关系的字段中设置百里香叶的值。我该怎么办？

在妍

类之间的关系是1:N。在 Thymeleaf 中，我创建了一个拆分表单对象来提交表单数据。但是当我按下发送时，它会发送，但我在屏幕上看不到任何数据。

教授班

@Entity
@Getter
@Setter
@Table(name = "professor")
@NoArgsConstructor(access = AccessLevel.PROTECTED)
@ToString(of = {"id", "username", "userid", "position", "sal", "hiredate"})
public class Professor {

    @Id @GeneratedValue
    @Column(name = "profno", nullable = false)
    private Long id;

    @Column(name = "name", nullable = false, length = 50)
    private String username;

    @Column(nullable = false, length = 50)
    private String userid;

    @Column(nullable = false, length = 20)
    private String position;

    private int sal;

    private String hiredate;

    private int comm;

    @ManyToOne(fetch = LAZY)
    @JoinColumn(name = "deptno")
    private Department department;

    @OneToMany(mappedBy = "professor")
    private List<Student> students = new ArrayList<>();

    public Professor(String username) {
        this.username = username;
    }

    public Professor(String username, String position) {
        this.username = username;
        this.position = position;
    }

    public Professor(String username, String position, int sal, String hiredate, int comm, String userid, Department department) {
        this.username = username;
        this.hiredate = hiredate;
        this.userid = userid;
        this.sal = sal;
        this.comm = comm;
        this.position = position;
        if (department != null) {
            setDepartment(department);
        }
    }

    // ===== Method ===== //
    public void setDepartment(Department department) {
        this.department = department;
        department.getProfessors().add(this);
    }

部门.班级

@Entity
@Getter
@Setter
@Table(name = "department")
@NoArgsConstructor(access = AccessLevel.PROTECTED)
@ToString(of = {"id", "name", "loc"})
public class Department {

    @Id @GeneratedValue
    @Column(name = "deptno", nullable = false)
    private Long id;

    @Column(name = "dname", length = 100)
    private String name;

    @Column(length = 100)
    private String loc;

    @OneToMany(mappedBy = "department")
    private List<Professor> professors = new ArrayList<>();

    @OneToMany(mappedBy = "department")
    private List<Student> students = new ArrayList<>();
    
    public Department(String name) {
        this.name = name;
    }

    public Department(String name, String loc) {
        this.name = name;
        this.loc = loc;
    }
}

教授表格.class

@Getter
@Setter
public class ProfessorForm {

    private Long id;

    @NotEmpty()
    private String username;
    private String userid;
    private String position;
    private String hiredate;
    private int sal;
    private int comm;
    private Department department;
}

控制器类

Professor professor = new Professor(form.getUsername(), form.getUserid(),
                form.getComm(), form.getHiredate(), form.getSal(), form.getPosition(), form.getDepartment());

百里香叶

    <form th:action="@{/professor/add}" th:object="${professorForm}" method="post">
        <div class="form-group">
            <label th:for="username">name</label>
            <input type="text" th:field="*{username}" class="form-control" placeholder="">
        </div>

        <div class="form-group">
            <label th:for="userid">id</label>
            <input type="text" th:field="*{userid}" class="form-control" placeholder="">
        </div>

        <div class="form-group">
            <label th:for="position">position</label>
            <input type="text" th:field="*{position}" class="form-control" placeholder="">
        </div>

        <div class="form-group">
            <label th:for="sal">sal</label>
            <input type="number" th:field="*{sal}" class="form-control" placeholder="">
        </div>

        <div class="form-group">
            <label th:for="hiredate">hiredate</label>
            <input type="date" th:field="*{hiredate}" class="form-control" placeholder="">
        </div>

        <div class="form-group">
            <label th:for="comm">comm</label>
            <input type="range" th:field="*{comm}" class="form-control" min="0" max="100" value="0" placeholder="">
        </div>

        <div class="form-group">
            <label th:for="departmentId">loc</label>
            <input type="text" th:field="*{department.loc}" class="form-control" placeholder="">
        </div>

最后确认是department.loc问题。我们应该如何处理这个问题？

维姆·德布劳威

我假设您希望 HTML 表单的用户为要创建的教授实体选择某个部门。支持这一点的最简单方法是添加一个 HTML 选择，显示所有可能的部门，允许用户选择一个。

要使用 Thymeleaf 实现这一点，您需要以下内容：

更新ProfessorForm以使用应引用的实体的主键（Department在本例中，因此使用long）：

public class ProfessorForm {

   // instead of: private Department department;
    private long departmentId;
}

在@GetMapping控制器方法中，返回所有部门名称和 ID。这需要填写 HTML 选择

List<DepartmentNameAndId> departments = ...
model.addAttribute( "departments", departments);

更新 Thymeleaf 模板以使用 HTML 选择：

<select th:field="*{departmentId}">
            <option th:each="department : ${departments}"
                    th:text="${department.name}"
                    th:value="${department.id}">
        </select>