Jsf javax.el.PropertyNotFoundException:targetunreachable，'；空'；外键引用返回null

我知道managedBean有问题，但我不知道是什么问题

当我从jsf页面尝试

departmentManagedBean.department.faculty.facultyName

时，它会给出一个空指针，如下所示：

javax.el.PropertyNotFoundException:/administrator/department/DepartmentRegistration.xhtml@30260 value=“#{departmentRequestBean.department.faculty.facultyName}”：无法访问目标，“null”返回null

---

---

---

value=“#{departmentRequestBean.department.faculty.facultyName}”：无法访问目标，“null”返回null

这基本上意味着以下值之一

• {departmentRequestBean.department}

• {departmentRequestBean.department.faculty}

在处理表单提交期间返回

null

。由于您自己明确创建了

部门

，因此这只能意味着

教员

仍然是

空的

要正确修复它，请在

DepartmentRequestBean

private Department department = new Department();

借

---

以这种方式在支持bean中初始化department类

public Department getDepartment() {
if(department == null){
department = (Department)super.getInstance(Department.class);
}
return department;
}

如果对象变为null，这将创建一个新的department对象

public class DepartmentSessionBean {
    @PersistenceContext(unitName = "ApplicationPU")
    private EntityManager em;

    public void persist(Department department) {     
        em.persist(department);
    }
}

public class Faculty implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @Basic(optional = false)
    @NotNull
    @Column(name = "FacultyID")
    private Integer facultyID;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 255)
    @Column(name = "FacultyName")
    private String facultyName;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "faculty", fetch = FetchType.EAGER)
    private List<Department> departmentList;

    public Faculty() {
    }

    public Faculty(Integer facultyID) {
        this.facultyID = facultyID;
    }

    public Faculty(Integer facultyID, String facultyName) {
        this.facultyID = facultyID;
        this.facultyName = facultyName;
    }

    public Integer getFacultyID() {
        return facultyID;
    }

    public void setFacultyID(Integer facultyID) {
        this.facultyID = facultyID;
    }

    public String getFacultyName() {
        return facultyName;
    }

    public void setFacultyName(String facultyName) {
        this.facultyName = facultyName;
    }

    public List<Department> getDepartmentList() {
        return departmentList;
    }

    public void setDepartmentList(List<Department> departmentList) {
        this.departmentList = departmentList;
    }
}

@ViewScoped public class DepartmentRequestBean {
@EJB
private DepartmentSessionBean departmentSessionBean;
private Department department = new Department();
public Department getDepartment() {
    return department;
}

public void setDepartment(Department department) {
    this.department = department;
}


public void save(){


        departmentSessionBean.persist(department);

}

public DepartmentRequestBean() {
    this.faculty = new Faculty();
}}

private Department department = new Department();

private Department department;

@PostConstruct
public void init() {
    department = new Department();
    department.setFaculty(new Faculty());
}

public Department getDepartment() {
if(department == null){
department = (Department)super.getInstance(Department.class);
}
return department;
}