Storing a jpa entity where only the timestamp changes results in updates rather than inserts (desire

Posted by David Schlenk on Stack Overflow See other posts from Stack Overflow or by David Schlenk
Published on 2010-05-11T16:39:55Z Indexed on 2010/05/11 16:44 UTC
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I have a JPA entity that stores a fk id, a boolean and a timestamp:

@Entity
public class ChannelInUse implements Serializable {
  @Id
  @GeneratedValue
  private Long id;
  @ManyToOne
  @JoinColumn(nullable = false)
  private Channel channel;
  private boolean inUse = false;
  @Temporal(TemporalType.TIMESTAMP)
  private Date inUseAt = new Date();
  ...
 }

I want every new instance of this entity to result in a new row in the table. For whatever reason no matter what I do it always results in the row getting updated with a new timestamp value rather than creating a new row. Even tried to just use a native query to run an insert but channel's ID wasn't populated yet so I gave up on that. I've tried using an embedded id class consisting of channel.getId and inUseAt. My equals and hashcode for are:

public boolean equals(Object obj){

if(this == obj) return true; if(!(obj instanceof ChannelInUse)) return false; ChannelInUse ciu = (ChannelInUse) obj; return ( (this.inUseAt == null ? ciu.inUseAt == null : this.inUseAt.equals(ciu.inUseAt)) && (this.inUse == ciu.inUse) && (this.channel == null ? ciu.channel == null : this.channel.equals(ciu.channel)) ); } /** * hashcode generated from at, channel and inUse properties. */ public int hashCode(){ int hash = 1; hash = hash * 31 + (this.inUseAt == null ? 0 : this.inUseAt.hashCode()); hash = hash * 31 + (this.channel == null ? 0 : this.channel.hashCode()); if(inUse) hash = hash * 31 + 1; else hash = hash * 31 + 0; return hash; } } I've tried using hibernate's Entity annotation with mutable=false. I'm probably just not understanding what makes an entity unique or something. Hit the google pretty hard but can't figure this one out.

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