Question

I wanna register a user using Spring MVC 3, Hibernate, and PostgresQL.
Here Is the form I wanna submit:

<form:form name="registerForm" method="post"
        action="registerNewUser.html" commandName="user">

        <table>

            <tr>
                <td><spring:message code="label.userName" /></td>
                <td><form:input path="userName" /></td>
                <td><form:errors path="userName" cssClass="error" /></td>
            </tr>

            <tr>
                <td><spring:message code="label.password" /></td>
                <td><form:password path="password" /></td>
                <td><form:errors path="password" cssClass="error" /></td>
            </tr>


            <tr>
                <td><spring:message code="label.password" /></td>
                <td><form:password path="retypePassword" /></td>
                <td><form:errors path="retypePassword" cssClass="error" /></td>
            </tr>

            <tr>
                <td colspan="2"><input type="submit"
                    value="<spring:message code="register.label" />" /></td>
            </tr>
        </table>

    </form:form>

here is the POJO I want to save:

@Entity
@Table(name = "user_table")
public class User {

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

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

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

    private String retypePassword;
        // getters setters

and here is the relevant part of the Controller:

@RequestMapping(value = "/registerNewUser", method = RequestMethod.POST)
public String saveNewUser(@ModelAttribute User user, BindingResult result, Model model, HttpSession session) {

    UserValidator validator = new UserValidator();
    validator.validateUser(user, result, userService.existingUser(user));
    String ret = REGISTER_USER;
    if (!result.hasErrors()) {
        user.setPassword(PasswordEncripter.md5(user.getPassword()));
        userService.save(user);
        ret = goToPractice(user, model, session);
    }
    return ret;
}

Because I feel it wasteful to store the value of retypePassword in the DB I did not create a column for that.
That caused the exception below when I submitted the form:

org.postgresql.util.PSQLException: ERROR: column user0_.retypepassword does not exist

I could easily fix this exception by adding the column “retypePassword” to the table but I still feel that would be wasteful. Is there any clever way to fix the problem without adding duplicate data in the DB?

Answer 1

You can mark retypePassword in entity with @Transient, this will instruct hibernate not to create column in table but still you can use this pojo to bind with spring mvc for validation purpose.

@Entity
@Table(name = "user_table")
public class User {

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

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

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

    @Transient
    private String retypePassword;
        // getters setters