Date saved but retrieved null in ElementCollection (or Embedded) property

I have an object of type Instance which contains an @ElementCollection of type Datapoint. Each datapoint has a timestamp and a value. In a test, I create some instances with their datapoints and save them, however, when I read any of those instances back from the database, the value for datapoints is set but the timestamp is null.

I am using: Cassandra 3.11.2 Kundera 3.12

persistence.xml

    <persistence-unit name="cassandra_pu">
        <provider>com.impetus.kundera.KunderaPersistence</provider>
        <properties>
            <property name="kundera.nodes" value="localhost"/>
            <property name="kundera.port" value="9042"/>
            <property name="kundera.keyspace" value="d2lablite"/>
            <property name="kundera.dialect" value="cassandra"/>
            <property name="kundera.ddl.auto.prepare" value="create" />
            <property name="kundera.client.lookup.class" value="com.impetus.kundera.client.cassandra.dsdriver.DSClientFactory" />
        </properties>
    </persistence-unit>

Datapoint.java

@Embeddable
public class Datapoint {
    @Column(name="timestamp")
    @Temporal(TemporalType.TIMESTAMP)
    private java.util.Date timestamp;

    @Column(name="value")
    private double value;

    public Datapoint() { }

    // Getters, setters
}

Instance.java

@Entity
@Table(name="instances")
public class Instance {
    @Id
    @Column(name="uuid")
    private String uuid;

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

    @ElementCollection
    @Column(name="datapoints")
    private List<Datapoint> datapoints;

    @ElementCollection
    @Column(name="metadata")
    private Map<String, String> metadata;

    @Temporal(TemporalType.TIMESTAMP)
    @Column(name="date")
    private Date date;

    public Instance() { }
}

So what I do is:

• Create an Instance, create a List<Datapoint>, set it to instance and persist the instance
• Check via cqlsh that the instance is saved and all datapoints have the timestamp saved as well
• Use the EntityManager’s find method to fetch an instance by its uuid, and it contains all values, including the date column, and its datapoints contain their values but the timestamp field in every datapoint is null.

I have also tried to use @Embedded and only 1 Datapoint instead of a list and the result is the same, timestamp is null.

What did I miss?

[devender-yadav]

Hi @milosjajac,

This issue is fixed and will be available in the next Kundera release.

[devender-yadav]

Hi @milosjajac,

Seems like an issue from Kundera side.