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copied!<p>there are two entity classes:</p> <pre><code>@Entity public class Place implements Serializable { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; @OneToMany(mappedBy = "place") private List<Event> events = new ArrayList<Event>(); private String name; //getters setters } @Entity public class Event implements Serializable { @Id @GeneratedValue(strategy=GenerationType.IDENTITY) private Long id; @OneToMany(mappedBy = "event" , cascade={CascadeType.PERSIST}) private List<Participant> participants = new ArrayList<Participant>(); @ManyToOne(optional=false,fetch=FetchType.EAGER) private Place place; private String name; // getters setters } </code></pre> <p>the generated tables: <pre><code>mysql> desc EVENT; +----------+--------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +----------+--------------+------+-----+---------+----------------+ | ID | bigint(20) | NO | PRI | NULL | auto_increment | | NAME | varchar(255) | YES | | NULL | | | PLACE_ID | bigint(20) | YES | MUL | NULL | | +----------+--------------+------+-----+---------+----------------+ mysql> desc PLACE; +----------+--------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +----------+--------------+------+-----+---------+----------------+ | ID | bigint(20) | NO | PRI | NULL | auto_increment | | LOCATION | varchar(255) | YES | | NULL | | | NAME | varchar(255) | YES | | NULL | | +----------+--------------+------+-----+---------+----------------+ </pre></code> Now, I'll code some Java so the Place and Event tables looks in this way:</p> <pre><code>+----+--------+ | ID | NAME | +----+--------+ | 1 | Prague | +----+--------+ +----+-------------+----------+ | ID | NAME | PLACE_ID | +----+-------------+----------+ | 1 | Programming | 1 | +----+-------------+----------+ </code></pre> <p>Now, I would like to pick a place and view all its events: <code><pre> // there's an ejb talking with persistence layer Place p = ejb.getPlaceWithId(1); </pre></code> and I would think that there's something more than empty collection in <code>p.events</code>, but there is not - based on my observations. Why?</p>

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