Re: [eclipselink-users] OneToMany Interface mapping

[James Sutherland <jamesssss@xxxxxxxxx>]

Please log an enhancement request for variable OneToMany and ManyToMany
mappings.

It might actually just work if you define the OneToManyMapping using a
DescriptorCustomizer and set its reference class to Paper and define its
selectionCriteria using query keys.

A workaround is to define a class that maps to a join table, and define a
VariableOneToOne in it.
i.e. Student - OneToMany - PaperAssociation - VariableOneToOne - Paper

Another option is to instead make Paper an abstract class, or define an
abstract class in addition to the interface and map it using TABLE_PER_CLASS
inheritance, or even JOINED or SINGLE_TABLE inheritance.

I suppose you could model it two ways on the database, you could use a join
table and type field, or just a normal 1-m and query each table and union
the result.



Afroozeh wrote:
> 
> Hi,
> 
> In my current project I must provide header interfaces for my
> entities. For example I have the Paper interface like this:
> 
> =======================
> public interface Paper {
>    public void submit();
>    public String title();
> }
> =======================
> 
> I have two different paper implementation and I want to map them to a
> relational database. For one to one operations the @VariableOneToOne
> annotation works well. I wonder why there is no @VariableOneToMany or
> @VariableManyToMany annotation. Somewhere in code I want to map a list
> of papers.
> 
> hibernate provides a @ManyToAny annotation that does the work but with
> cost of an intermediate table like many to many relationships.
> 
> My first question is how should I do this with EclipseLink? Second, is
> this kind of mapping inherently requires an intermediate table?
> 
> Regards
> 
> 


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