Christian Beikov ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=557058%... ) *updated* an issue Hibernate ORM ( https://hibernate.atlassian.net/browse/HHH?atlOrigin=eyJpIjoiMzI0NTFjYjg4... ) / Bug ( https://hibernate.atlassian.net/browse/HHH-14017?atlOrigin=eyJpIjoiMzI0NT... ) HHH-14017 ( https://hibernate.atlassian.net/browse/HHH-14017?atlOrigin=eyJpIjoiMzI0NT... ) Adding PK proxy using field access to non-pk mapped collection results in NULL constraint violation ( https://hibernate.atlassian.net/browse/HHH-14017?atlOrigin=eyJpIjoiMzI0NT... ) Change By: Christian Beikov ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=557058%... ) A simple model that maps a collection through a unique column {code:java} @Entity @Table(name = "base_object") public class BaseObject implements Serializable { @Id @Column(name = "id") @GeneratedValue(strategy = GenerationType.AUTO) private Integer id; @Column(name = "name", nullable = false, unique = true) private String name; @ManyToMany @JoinTable( name = "related_objects", joinColumns = @JoinColumn(name = "base_name", referencedColumnName = "name"), inverseJoinColumns = @JoinColumn(name = "related_name", referencedColumnName = "name") ) private Set<RelatedObject> related = new HashSet<>(); } @Entity @Table(name = "related_object") public class RelatedObject { @Id @Column(name = "id") @GeneratedValue(strategy = GenerationType.AUTO) private Integer id; @Column(name = "name", nullable = false, unique = true) private String name; } {code} When trying to add a {{RelatedObject}} reference to the collection, the flushing fails with a NULL constraint violation, although the proxy is lazily initialized. {code:java} BaseObject b = entityManager.find(BaseObject.class, bId); RelatedObject r = entityManager.getReference(RelatedObject.class, rId); b.getRelated().add(r); entityManager.flush(); {code} Note that it works when using property mapping instead, so this seems to be related to the proxy not being narrowed before being accessed. ( https://hibernate.atlassian.net/browse/HHH-14017#add-comment?atlOrigin=ey... ) Add Comment ( https://hibernate.atlassian.net/browse/HHH-14017#add-comment?atlOrigin=ey... ) Get Jira notifications on your phone! Download the Jira Cloud app for Android ( https://play.google.com/store/apps/details?id=com.atlassian.android.jira.... ) or iOS ( https://itunes.apple.com/app/apple-store/id1006972087?pt=696495&ct=Em... ) This message was sent by Atlassian Jira (v1001.0.0-SNAPSHOT#100126- sha1:dd08494 )