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Design Advice?

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dbh21

Post subject: Design Advice?

Posted: Fri Mar 29, 2013 4:06 pm

Newbie

Joined: Fri Mar 29, 2013 4:00 pm
Posts: 1

Hey. I'm trying to understand how to best design a set of tables in hibernate. For simplicity, I have two classes:

Code:

public class Security {
   @Id
   @Column
   public String symbol;


   public List<Earnings> earnings;
    ...

And

Code:

public class Earnings {
   public Security security;
   public Date date;
   ...

The Security has a OneToMany relationship with the Earnings Table. The Security only needs the symbol as the uniqueid, while the Earnings table would need the Symbol of the security plus a date to ensure uniqueness.

Now the question is how best to setup the relationship with hibernate and annotations.

Is it best to create a Composite Key in the Earnings and then use a OneToMany mapping using the composite key? If so, I get circular references.

How would you map the two entities?

Thanks in advance

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orwtech@gmail.com

Post subject: Re: Design Advice?

Posted: Wed Apr 10, 2013 9:26 am

Newbie

Joined: Wed Mar 13, 2013 11:32 am
Posts: 16

Hi

You can map it something like this:

Code:

public class Security {
   @Id
   @Column
   public String symbol;

   @OneToMany(mappedBy="security")
   public List<Earnings> earnings;
    ...

Code:

public class EarningsPK {
   public Security security;
   public Date date;
}

Code:

@IdClass(EarningsPK.class)
public class Earnings {

   @Id
   @OneToOne(fetch=FetchType.LAZY)
   @JoinColumn(name="symbol", referenceColumnName="symbol")
   public Security security;

   @Id
   public Date date;
   ...

Br

Jesper

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