[jboss-user] [JBoss Seam] - Handling dynamic data in RDBMS (i.e. no direct column mappin

[tailor]

Hi all,

I'm actually a bloody beginner in Seam but somehow managed to succesfully develop my first web app in Seam. Right now I'm trying to solve a problem where I need some further advice.

I have chosen a somewhat dynamic approach to save additional data of a user in the RDBMS. There are four main tables.

user (id, name)
  | record (id, user_id)
  | data_value (id, record_id, data_type_id, value)
  | data_type (id, name, description)
  | 
  | The data_type table is a simple table that holds a list of possible fields so to say where you can save values for. Those values should be saved for a user. Each user has its own record which consists of defined data_types. The relation data_value brings it all together, this is where the actual values for the defined data_values are stored.
  | 
  | According SQL Create-Statements (MySQL): http://pastebin.com/f5883f89d
  | According Entity Beans: http://pastebin.com/m501ed44e
  | 
  | I created a SLSB to retrieve a list of "DataValue" objects from the db.
  | 
  | @Stateless
  |   | @Name("recordList")
  |   | public class RecordListAction implements RecordList, Serializable {
  |   | 
  |   | 	private static final long serialVersionUID = 1L;
  |   | 
  |   | 	@PersistenceContext
  |   | 	private EntityManager em;
  |   | 
  |   | 	@In
  |   | 	private User user;
  |   | 
  |   | 	@DataModel
  |   | 	private List<DataValue> dataValues;
  |   | 
  |   | 	// needed to prevent spurious warning
  |   | 	// getResultList() returns a non generic version of List
  |   | 	@SuppressWarnings("unchecked")
  |   | 	@Factory("dataValues")
  |   | 	public void getDataValues() {
  |   | 		dataValues = em.createQuery(
  |   | 				"select dv from DataValue dv "
  |   | 						+ "inner join dv.record as record "
  |   | 						+ "inner join dv.dataType as dataType "
  |   | 						+ "where record.user.id = :userId")
  |   | 				.setParameter("userId", user.getId())
  |   | 				.getResultList();
  |   | 	}
  |   | 
  |   | 	@Remove
  |   | 	public void destroy() {
  |   | 	}
  |   | }
  | 
  | I am able to output this list in a facelet.
  | 
  | <h:dataTable id="dataValues" var="dataValue" value="#{dataValues}" rendered="#{dataValues.rowCount gt 0}">
  |   | 	<h:column>
  |   | 		<f:facet name="header">Name</f:facet>
  |   | 		<h:outputText value="#{dataValue.dataType.name}" />
  |   | 	</h:column>
  |   | 	<h:column>
  |   | 		<f:facet name="header">Value</f:facet>
  |   | 		<h:outputText value="#{dataValue.value}" />
  |   | 	</h:column>
  |   | 	</h:dataTable>
  | And now it comes to the interesting part (finally!). I want to be able to modify (for now; creating and deleting should be integrated later) the "DataValue" objects. Everything I did before was straightforward, i.e. retrieve one row of a table and edit its columns. But now I retrieve one or more rows with two columns (one with the data_type.name and one with the data_value.value) and want to edit them.
  | 
  | I currently do not know where to start solving this problem. Maybe anyone of you can give me some hints to start?

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