[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-4479) We should be able to implement Joins using formulas with Annotations
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http://opensource.atlassian.com/projects/hibernate/browse/HHH-4479?page=c...
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Paul Benedict commented on HHH-4479:
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Sharath, thank you for explaining. I gathered myself too it was because you wanted to
preserve column ordering, but why is it important to keep? I do ask that seriously :-) All
the information to link up relationships exist in @JoinColumn(name=,
referencedColumnName=). As long as the referenced column names are specified, the order
isn't important.
Let me redo your example to demonstrate:
@ManyToOne
@JoinColumn(name="order_nbr", referencedColumnName="order_nbr")
@JoinFormula(value="'true'",
referencedColumnName="is_default")
public Menu getOrder() {
return order;
}
Because the referencedColumnNames attributes are present, the SQL should end up as:
...WHERE _reftable.order_nbr = this.order_nbr and _reftable.is_default = 'true'
Because Joins are name-based, not positional-based, that's why I think we can
mix-and-match. When possible, join columns should remain JPA-pure and allow
Hibernate's extensions to add on top.. Your patch is great, but I think it farther
than necessary to make the feature work. Does this make sense to you?
We should be able to implement Joins using formulas with Annotations
---------------------------------------------------------------------
Key: HHH-4479
URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-4479
Project: Hibernate Core
Issue Type: New Feature
Components: annotations
Reporter: Sharath Reddy
Assignee: Sharath Reddy
Priority: Minor
Fix For: 3.5
Attachments: HHH-4479.patch, HHH-4479second.patch
This article published on the O'Reilly web site -
http://onjava.com/pub/a/onjava/2005/08/03/hibernate.html?page=3 - describes how to
implement joins with formulas, using the hbm xml files. We should be able to do the same
with annotations:
<hibernate-mapping>
<class name="Company" table="Company">
<id name="id" />
<many-to-one
name="defaultContactPerson"
property-ref="defaultContactPerson">
<column name="id"/>
<formula>1</formula>
</many-to-one>
</class>
<class name="Person" >
<id name="id" />
<properties name="defaultContactPerson">
<property name="companyID" />
<property name="defaultFlag" />
</properties>
</class>
</hibernate-mapping>
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