OK, we will see
You have the @AssociationOverride annotation in which the API says:
This annotation is used to override a mapping of properties or a many-to-one or one-to-one mapping for an entity relationship.
and
It can be applied to an entity that extends the displayed superclass to override the many-to-one or one-to-one mapping defined by the displayed superclass
I have not seen either @ManyToOne or @OnoToOne in your question. So there is something wrong with your question.
But I saw the following log in your stacktrace
A foreign key that refers to Reporting from a Report has the wrong number of columns. should be 2
You have a primary key defined by the @EmbeddedId annotation, which has two properties (fileName and xmlContent)
Now look at @CollectionOfElements
@CollectionOfElements(fetch=FetchType.EAGER) @JoinTable(name="t_reports", // Your mistake goes here joinColumns=@JoinColumn (name="log_report")) @Fetch(FetchMode.SELECT) private List<ReportingFile> reports;
Its foreign key contains only one property , while your primary Compound key contains two properties . Both must match . This explains why you see this nice message.
A foreign key that refers to Reporting from a Report has the wrong number of columns. should be 2
Your correct display should look like this:
@CollectionOfElements(fetch=FetchType.EAGER) @JoinTable(name="t_reports", joinColumns={ // The number of columns defined by our Compound primary key (2) // must match the number of columns defined by its Foreign key (2) @JoinColumn(name="file_name", referencedColumnName="file_name"), @JoinColumn(name="xml_content", referencedColumnName="xml_content")}) @Fetch(FetchMode.SELECT) private List<ReportingFile> reports;
And one more thing: I don't know if your target Clob database supports as a primary key. Therefore, keep this in mind.
Added original answer according to your answer
1º First Scenario ( without @CollectionOfElements)
@Entity public class Reporting {
Keep in mind the following: Hibernate does not allow you to define two properties in which both have the same column . Because of this, I have to define insertable = false, updatable = false in the fileName property.
And when I do the following
Reporting reporting = new Reporting(); reporting.setFileName("home.pdf"); ReportingFile reportingFile = new ReportingFile(); // It will not persisted because of insertable=false, updatable=false reportingFile.setFileName("home.pdf"); reportingFile.setXmlContent(someClobObject); session.save(reporting); // It works
2º First Scenario ( with @CollectionOfElements)
@Entity public class Reporting { // You said you just want a single fileName as primary key @Id @Column(name="file_name", nullable=false) private String fileName; // You said you still want to have the whole ReportingFile object @Embedded private ReportingFile reportingFile; @CollectionOfElements(fetch=FetchType.EAGER) @JoinTable( name="t_reports", joinColumns=@JoinColumn (name="file_name", referencedColumnName="file_name", insertable=false, updatable=false)) private List<ReportingFile> reports; @Embeddable public static class ReportingFile implements Serializable { // You must set up insertable=false, updatable=false @Column(name="file_name", insertable=false, updatable=false) private String fileName; @Column(name="xml_content") private Clob xmlContent; } }
And when I do the following
Reporting reporting = new Reporting(); reporting.setFileName("home.pdf"); ReportingFile reportingFile = new ReportingFile(); // It will not persisted because of insertable=false, updatable=false reportingFile.setFileName("home.pdf"); reportingFile.setXmlContent(someClobObject); reporting.getReports().add(reportingFile); session.save(reporting); // It does not work
Hibernate will complain
repeat column in collection mapping: report column: file_name
So, when you have @CollectionOfElements that uses a foreign key, it will not work as expected . But you can do a workaround
@Entity public class Reporting { // You said you just want a single fileName as primary key @Id @Column(name="file_name", nullable=false) private String fileName; // You said you still want to have the whole ReportingFile object @Embedded private ReportingFile reportingFile; // Your workaround goes here @CollectionOfElements(fetch=FetchType.EAGER) @JoinTable( name="t_reports", joinColumns=@JoinColumn (name="file_name", referencedColumnName="file_name")) private List<Clob> xmlContents; @Transient public List<ReportingFile> getReports() { List<ReportingFile> reports = new ArrayList<ReportingFile>(); for(Clob xmlContent: getXmlContents()) reports.add(new ReportingFile(getFileName(), xmlContent)); return reports; } @Embeddable public static class ReportingFile implements Serializable { // required no-arg constructor public ReportingFile() {} public ReportingFile(String fileName, Clob xmlContent) { this.fileName = fileName; this.xmlContent = xmlContent; } // You must set up insertable=false, updatable=false @Column(name="file_name", insertable=false, updatable=false) private String fileName; @Column(name="xml_content") private Clob xmlContent; } }
Note that you can define the @Embeddable class as static when used inside your own class.