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 Post subject: @ManyToAny without discriminator column
PostPosted: Thu Aug 10, 2017 8:32 am 
Newbie

Joined: Thu Aug 03, 2017 9:25 am
Posts: 6
Hello,
I am working on Kodo to Hibernate migration in a legacy system.
I have the following code structure:

Code:
@Entity
@DiscriminatorValue(value = "S")
public class StructuredDataParameter extends Parameter {
    private NFStructuredDataObject dataObject;
...
}

public interface NFStructuredDataObject {
...
}

public abstract class NFStructuredDataObjectAbstractImpl implements NFStructuredDataObject {
...
}


NFStructuredDataObjectAbstractImpl is extended by multiple entity classes.

Currently using Kodo (JDO), the field dataObject was stored in database in PARAMETER table in DATA_OBJECT column as string value:
Code:
com.xyz.data.ChildrenData:com.xyz.data.ChildrenData-175829

where 175829 is an example primary key in table CHILDREN_DATA and com.xyz.data.ChildrenData is an entity class that extends NFStructuredDataObjectAbstractImpl
Kodo did it by default. How can I achieve such behavior in Hibernate?
I thought about @ManyToAny with @JoinFormula but it needs an additional discriminator column. Maybe there's a way to implement custom UserType that will resolve the target class and ID based on parts of the string value?
I need to use Hibernate 4.2.18 and since the schema is legacy I shouldn't change it.


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 Post subject: Re: ManyToAny without discriminator column
PostPosted: Sun Aug 13, 2017 2:21 am 
Hibernate Team
Hibernate Team

Joined: Thu Sep 11, 2014 2:50 am
Posts: 1638
Location: Romania
You can also use SINGLE_TABLE entity inheritance with the help of @DiscriminatorColumn.

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If you liked my answer, you are going to love my High-Performance Java Persistence book and my blog as well.


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