Question

I have similar problem as is described in Spring Framework – New object is created in DB instead of updating but I have two entities: Author and Department in @ManyToOne relation. One department has many authors and one author belongs to one department. When I update an author, author details are updated, but department is inserted which leads to duplicate entries. From aforementioned link I know that I’m probably missing department ID, but I don’t know how to tie department with its ID.

Author entity (without getters and setters)

@Entity
@Table(name = "author")
public class Author implements Serializable {

    @Id
    @Column(name = "idauthor")
    @GeneratedValue
    private Integer idAuthor;

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

    @ManyToOne(cascade = CascadeType.ALL)
    private Department department;
}

Department entity (without getters and setters)

@Entity
@Table(name="department")
public class Department implements Serializable {

    @Id
    @Column(name="iddepartment")
    @GeneratedValue
    private Integer iddepartment;

    @Column(name="name", unique=true)
    private String name;
}

Methods for update operatio of Author in AuthorController

@Controller
@RequestMapping("/author")
public class AuthorController {

    @Autowired
    private AuthorService authorService;

    @Autowired
    private DepartmentService departmentService;

    @RequestMapping(value="/save/{authorId}", method = RequestMethod.GET)
    public String renderUpdateForm(@PathVariable("authorId") Integer authorId, ModelMap model) {
        model.addAttribute("author", authorService.getAuthorByID(authorId));

        model.addAttribute("departmentList", departmentService.listDepartment());
        return "author.save";
    }

    @RequestMapping(value="/save/{authorId}", method = RequestMethod.POST)
    public String updateAuthor(@ModelAttribute("idAuthor") Author author, BindingResult result, SessionStatus status) {
        authorService.updateAuthor(author);
        status.setComplete();
        return "redirect:/author";
    }
}

authorService.updateAuthor(author); calls service which calls DAO class with method:

@Repository
@Transactional
public class AuthorDAOImpl implements AuthorDAO {

    @Autowired
    private SessionFactory sessionFactory;

    @Override
    public void updateAuthor(Author author) {
        sessionFactory.getCurrentSession().update(author);
    }
}

and finally JSP with form

<form:form method="post" action="${pageContext.request.contextPath}/author/save" modelAttribute="author">
<form:hidden path="idAuthor" />
    <table>
    <tr>
        <td>
            <form:label path="name">
                <spring:message code="label.author.name"/>
            </form:label>
        </td>
        <td><form:input path="name" /></td>
    </tr>
    <tr>
        <td>
            <form:label path="department.name">
                <spring:message code="label.author.department"/>
            </form:label>
        </td>
        <td>
            <form:select path="department.name">
                <form:options items="${departmentList}" itemValue="name" itemLabel="name" />
            </form:select>
        </td>        
    </tr>
    <tr>
        <td colspan="2">
            <input type="submit" value="<spring:message code="label.update" />
        </td>
    </tr>
</table>
</form:form>

And the error I’m getting is

com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException:
Duplicate entry ‘custom department
name’ for key ‘name’

How should I pass ID to department or fix my problem? Thanks for your advises.

Answer 1

I had to add Formatters SPI (see documentation for more information) for each POJO. Then hibernate updated objects instead of saving duplicity.