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Github project to reproduce: [https://raw.githubusercontent.com/tmonney/hibernate-mapsid]
Suppose a pair of entities defined with the same composite primary key:
{code | : title=Parent.java}
@Entity
public class Parent {
@EmbeddedId
public Key id;
@OneToOne(cascade = CascadeType.ALL, mappedBy = "parent")
public Child child;
@Basic
public String value;
}
{code}
{code | : title=Child.java}
@Entity
public class Child {
@EmbeddedId
private Key id;
@OneToOne
@MapsId
@JoinColumns({
@JoinColumn(name = "id1", referencedColumnName = "id1"),
@JoinColumn(name = "id2", referencedColumnName = "id2")
})
public Parent parent;
@Basic
public String value;
}
{code}
{code | : title=Key.java}
@Embeddable
public class Key implements Serializable {
private static final long serialVersionUID = 1L;
@Column(name = "id1")
public Long id1;
@Column(name = "id2")
public Long id2;
public Key() {
}
public Key(Long id1, Long id2) {
this.id1 = id1;
this.id2 = id2;
}
@Override
public int hashCode() {
return Objects.hash(id1, id2);
}
@Override
public boolean equals(Object obj) {
if (!(obj instanceof Key)) {
return false;
}
Key that = (Key) obj;
return Objects.equals(this.id1, that.id1) && Objects.equals(this.id2, that.id2);
}
}
{code}
The bug manifests itself when loading a {{Parent}} entity, getting its {{child}}, modifying some of its fields and finally flushing the entity manager:
{ code noformat }
Batch update returned unexpected row count from update [0]; actual row count: 0; expected: 1
{ code noformat }
This is because Hibernates executes the following query:
{code:sql}
update FailingChild set value=? where id1=? and id2=?
{code}
And passes the *same value* for {{id1}} and {{id2}}, which is obviously wrong.
Interestingly enough, everything works OK if the mapping of the {{{Child}} class is changed as follows (notice the second join column of the parent is renamed):
{code | : title=Child.java}
@Entity
public class Child {
@EmbeddedId
public Key id;
@OneToOne
@MapsId
@JoinColumns({
@JoinColumn(name = "id1", referencedColumnName = "id1"),
@JoinColumn(name = "renamed_id2", referencedColumnName = "id2")
})
public Parent parent;
@Basic
public String value;
}
{code}
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