Integrity constraint violation

Using the Play! Framework, i have the following two models:

@Entity
public class User extends Model {
    public String firstName;
    public String lastName;
    public String email;
    public String password;
    public boolean isAdmin;

    @OneToMany(mappedBy="id", cascade=CascadeType.ALL)
    public List<Site> sites;

    public User(String firstName, String lastName, String email, String password) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.email = email;
        this.password = password;
    }

    public static User connect(String email, String password) {
        return User.find("byEmailAndPassword",email,Crypto.passwordHash(password)).first();
    }

    public static User findUser(String email) {
        return User.find("byEmail",email).first();
    }

    public static User createUser(String firstName, String lastName, String email, String password, boolean isAdmin) {
        String pw = Crypto.passwordHash(password);

        User u = new User(firstName, lastName, email, pw);
        u.isAdmin = isAdmin;
        u.save();
        return u;
    }
}

@Entity
public class Site extends Model {

    public UUID siteId;

    public String alias;
    public String protocol;
    public String host;
    public String username;
    public String password;
    public int port;
    public String rootPath;

    @Lob
    public String description;

    @ManyToOne
    public User user;

    public Site(User user, String alias, String protocol,开发者_如何学JAVA String host, String username, String password) {
        this.user = user;
        this.alias = alias;
        this.protocol = protocol;
        this.host = host;
        this.username = username;
        this.password = password;
        this.port = 21;
        this.siteId = UUID.randomUUID();

    }
}

When i try to run the following test:

public class BasicTest extends UnitTest {

    @Before
    public void setup() {
        Fixtures.deleteAll();
    }

    @Test
    public void createAndRetrieveUser() {
        new User("Jason","Miesionczek","something","something").save();
        User jason = User.find("byEmail", "something").first();

        assertNotNull(jason);
        assertEquals("Jason", jason.firstName);
    }

    @Test
    public void userSite() {
        new User("Jason","Miesionczek","something","something").save();
        User jason = User.find("byEmail", "something").first();

        new Site(jason, "InterEditor","ftp","something","something","something").save();

        List<Site> sites = Site.find("byUser", jason).fetch();

        assertEquals(1, sites.size());

        Site site1 = sites.get(0);
        assertNotNull(site1);
        assertEquals("InterEditor", site1.alias);
        assertNotNull(site1.siteId);
    }



}

And i get this error:

A javax.persistence.PersistenceException has been caught, org.hibernate.exception.ConstraintViolationException: could not insert: [models.Site]
In /test/BasicTest.java, line 27 :
new Site(jason, "InterEditor","ftp","something","something","something").save();

Log output:

00:06:26,184 WARN  ~ SQL Error: -177, SQLState: 23000
00:06:26,184 ERROR ~ Integrity constraint violation - no parent FK2753674FD92E0A
 table: USER in statement [insert into Site (id, alias, description, host, passw
ord, port, protocol, rootPath, siteId, user_id, username) values (null, ?, ?, ?,
 ?, ?, ?, ?, ?, ?, ?)]

Can anyone help me understand what the error means and what i am doing wrong?

---

Your problem here is the mapping between the Site model class and the User model class. The error given is a missing foreign key.

If you comment out the Site list in your User class, your test will pass. So that has narrowed down the problem.

Update:

The problem is because when your Site object is saved, it will save the child objects first (which includes the User object). When this happens, it is trying to create a reference to the Site object (due to the mappedBy parameter), but this has not been saved yet (this will be done AFTER the User object is saved).

So, an alternative would be to map by a value you do have access to (such as the siteId), or add the User to the Site after it has been saved (so the ID value has been generated.

I changed your code to be mappedBy="siteId" and the test run fine.

---

I solved such a problem by using "INITIALLY DEFERRED DEFERRABLE" in Oracle, this delays the checking until you commit the whole transaction !