CODEWITHSUNDEEP
javahibernate
jds
jds

Reputation: 8259

@ManyToOne mapping in Hibernate not working

I have two classes, Invite and Event with a many-to-one mapping: one event has many invites. Here are the relevant snippets of code/SQL with Hibernate annotations:

db.Events

+-------------+--------------+------+-----+---------+----------------+
| Field       | Type         | Null | Key | Default | Extra          |
+-------------+--------------+------+-----+---------+----------------+
| event_id    | int(11)      | NO   | PRI | NULL    | auto_increment |
| name        | varchar(255) | YES  |     | NULL    |                |
+-------------+--------------+------+-----+---------+----------------+

db.Invites

+-----------+--------------+------+-----+---------+----------------+
| Field     | Type         | Null | Key | Default | Extra          |
+-----------+--------------+------+-----+---------+----------------+
| invite_id | int(11)      | NO   | PRI | NULL    | auto_increment |
| name      | varchar(255) | YES  |     | NULL    |                |
| event_fk  | int(11)      | NO   | MUL | NULL    |                |
+-----------+--------------+------+-----+---------+----------------+

DbInvite.java

@ManyToOne
private DbEvent event;

public DbInvite() {
}

public DbInvite(String name, DbEvent event) {
    this.name = name;
    this.event = event;
}

// getters and setters

DbEvent.java

@OneToMany(mappedBy = "event")
private Set<DbInvite> invites;

public DbEvent() {
}

public DbEvent(String name) {
    this.name = name;
}

// getters and setters

Finally, I--and this is where most Hibernate examples appear to stop--I create my instances in the following way:

DbEvent dbEvent = new DbEvent(name);
DbInvite dbInvite = new DbInvite(name, dbEvent);

The error I receive is:

org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions
ERROR: Unknown column 'event_event_id' in 'field list'

Where am I going wrong? Where does event_event_id come from when the primary key is clearly event_id?

Upvotes: 0

Views: 353

Answers (2)

Dragan Bozanovic
Dragan Bozanovic

Reputation: 23552

You need to specify join column for many-to-one, otherwise defaults are assumed by JPA/Hibernate.

Upvotes: 1

Juan Henao
Juan Henao

Reputation: 220

When you do:

DbEvent dbEvent = new DbEvent(name);
//the id is setted in when persist into the db
dbEvent = someMethodThatPersistInDb(dbEvent);
//now the object have the id created in the db now insert the other one
DbInvite dbInvite = new DbInvite(name, dbEvent);
someMethodThatPersistInDb(dbInvite);

i hope that can help you, maybe you can post the rest of the mapping class to check the code.

Upvotes: 0

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