General Mapping for Nested Composites: Best Approach

jcmorris · **Posted:** Mon May 19, 2008 3:49 am

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Hibernate version:3.2

Mapping documents:none so far

Code between sessionFactory.openSession() and session.close():none so far

Full stack trace of any exception that occurs:n/a

Name and version of the database you are using:mySQL 5.0

The generated SQL (show_sql=true):none

Debug level Hibernate log excerpt:n/a

Problems with Session and transaction handling? No

Read this: http://hibernate.org/42.html

Hi All,
I've searched the FAQs and tutorials, and I can't find an answer to what I think is a simple mapping: multiple nested composites. For example, how do I map the following classes? A machine instance has a Set of control panels, each of which has a Set of controls. Machine is an entity, and ControlPanel and Control are value types. What if Machine had more than one such collection? What is the general mapping pattern for X is composed of a set of Y's, and Y is composed of a set of Zs (ad infinitum)?

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Code:

public class Machine {
   private Set controlPanels;
   private long id;
   private String name;
   
   public Set getControlPanels() {return controlPanels;}
   public void setControlPanels(Set controlPanels) {this.controlPanels = controlPanels;}
   public long getId() {return id;}
   public void setId(long id) {this.id = id;}
   public String getName() {return name;}
   public void setName(String name) {this.name = name;}
}

public class ControlPanel {
   private Set controls;
   private long id;
   private String name;
   
   public Set getControls() {return controls;}
   public void setControls(Set controls) {this.controls = controls;}
   public long getId() {return id;}
   public void setId(long id) {this.id = id;}
   public String getName() {return name;}
   public void setName(String name) {this.name = name;}
}

public class Control {
   private long id;
   private String name;
   
   public long getId() {return id;}
   public void setId(long id) {this.id = id;}
   public String getName() {return name;}
   public void setName(String name) {this.name = name;}
}

==========================

Thanks for all assistance. Meanwhile, I'll keep looking and experimenting. (Yes, I have Hibernate in Action!)