[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-4479) We should be able to implement Joins using formulas with Annotations

[Sharath Reddy (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-4479?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=34146#action_34146 ] 

Sharath Reddy commented on HHH-4479:
------------------------------------

Hi Paul,

As Emmanuel commented here (http://opensource.atlassian.com/projects/hibernate/browse/HHH-4382) :  

'My idea was to have a
@JoinColumnOrFormulas
which contains an array of
@JoinColumnOrFormula(
   joinColumn=@JoinColumn, formula=@Formula
)'

The rationale behind that is to be able to keep the column ordering even if formula and columns are mix and matched.'

Example: 

@ManyToOne
@JoinColumnsOrFormulas(
{ 
  @JoinColumnOrFormula(column=@JoinColumn(name="order_nbr", referencedColumnName="order_nbr")),
  @JoinColumnOrFormula(formula=@JoinFormula(value="'true'", referencedColumnName="is_default"))
})
public Menu getOrder() {
    return order;
}
 
@JoinColumns is part of the Java Persistence API, and @JoinFormula is a Hibernate vendor-specific extension to the JPA standard. I believe we can't mix-and-match them. 

If you want to discuss this in more detail, we can get together on chat or something....





> 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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