Mapping a relationship between 3 entities in Hibernate

I am trying to get to grips with hibernate and have a problem trying to map a relationship between 3 entities:

For example I have the following classes:

Distributor (id, name) e.g.: TNT, UPS, Fed Ex and each distributor has a selection of ShippingMethod (id, name, description) e.g.: Super saver, overnight international, Next Day and each shipping method has a series of ShippingOption (id, name, default, active, cost, availability) and each of these are specific to a particular distributor.

To do that in a DB I would have a table for Distributor, a table for ShippingMethods and a table for ShippingOptions which would have a FK relationship to Distributor and ShippingMethods.

However, in my domain model I would like to have two classes - Distributor() which would contain a list of ShippingOption() classes. Shi开发者_运维百科ppingOption() is a class combined from both ShippingMethod() and ShippingOption() (I've left out getters etc for brevity below):

@Entity
@Table(name = "shipping_option")
public class ShippingOption {

    @Column(name = "is_active", nullable = false)
    private boolean isActive = false;
    @Column(name = "is_default", nullable = false)
    private boolean isDefault = false;
    @Column(name = "cost", nullable = false)
    private BigDecimal cost = BigDecimal.ZERO;

    private ShippingMethod shippingMethod = new ShippingMethod();

    public ShippingOption() {

    }

    public ShippingOption(boolean isDefault, BigDecimal cost, ShippingMethod shippingMethod) {
            setDefault(isDefault);
            cost(cost);    
    setShippingMethod(shippingMethod); 
    }

    public void setDefault(boolean isDefault) {

        this.isDefault = isDefault;
    }

    public void setShippingMethod(ShippingMethod shippingMethod) {

        this.shippingMethod = shippingMethod;
    }
}

Is it possible to model this in Hibernate and how? If you need more information please let me know. Not sure if this is relevent but I am using spring mvc 3 also.

Cheers

Morris

Joining three tables is possible with hibernate. I have had similar problem where (In your example) ShippingOption had ManyToOne relation with Distributor and ShippingMethod.

Distributor (d_id, name)
ShippingMethod (sm_id, name, description)
ShippingOption (sp_id, d_id, sm_id, name, default, active, cost, availability, foreign key(d_id), foreign key(sm_id)) 

I guess this is how your table looks like. May be I will answer the problem I solved and you can figure out yours. My pojo looked like this,

@Entity
@Table(name = "shipping_option")
public class ShippingOption {

  //..all other columns to retrive
  @JoinColumn(name = "d_id", referencedColumnName = "d_id")
  @ManyToOne
  private ShippingMethod shippingMethod

  @JoinColumn(name = "sm_id", referencedColumnName = "sm_id")
  @ManyToOne
  private Ditributor distributor; //Make sure you have Distributor and ShippingMethod Pojos defined


  public ShippingMethod getShippingMethod() {
      return this.shippingMethod;
  }

  public void setShippingMethod(ShippingMethod sMethod) {
      this.shippingMethod = sMethod;
  }

  // Getter setter for Distributor and other columns as well goes here.    
}

I have to get all the ShippingOption of a given Distributor name. The mysql query would be something link this

 select d.d_id, d.name, sm.name, so.name, so.default from Distributor as d, ShippingMethod as sm, ShippingOption as so where d.d_id = so.d_id and so.sm_id = so.sm_id and d.name = 'FedEx';

On the hibernate implementation,

   public List<ShippingOption> getAllShipingOptionByDistributor(final String distName) {

   //....
   return List<ShippingOption>  session.crateCriteria(ShippingOption.class)
  .createAlias("distributor", "distributor")     //distributor is the member of ShippingOption of type Distributor, see the above pojo definition.
  .add(Restrictions.eq("distributor.name", distName);
  .createAlias("shippingMethod", "sm")
  .list();

Thats it, i would get a list of ShippingOption in which each would have its corresponding Distributor and ShippingMethod.