Sample jpacontainer manytomany

Vaadin 6 / 7 / 8 Framework Data Binding
1

is there an example about jpacontainer manytomany on your site?

thank you

2

I got this working.

My domain class:


@Entity
public class Trader {
	@Id
	private long id;
	private String name;
	private String email;

	@ManyToMany
	private Set<Stock> stocks;
// getters/setters
}


@Entity
public class Stock {
	@Id
	private String symbol;
	private String name;
	@ManyToMany(mappedBy = "stocks")
	private Set<Trader> traders;
// getters/setters
}

Now, when I want to create a new Stock which refers to particular Trader:


				EntityItem<Stock> stockItem;
				Item stockTableItem = newStocksTable.getItem(newStocksTable.getValue()); // newStocksTable is a Table
				if( !stocks.containsId( stockTableItem.getItemProperty("symbol") ) ){ // stocks is a JPAContainer for stocks
					final BeanItem<Stock> stockBeanItem = new BeanItem<Stock>(new Stock());
					stockBeanItem.getItemProperty("symbol").setValue( stockTableItem.getItemProperty("symbol") );
					stockBeanItem.getItemProperty("name").setValue( stockTableItem.getItemProperty("name") );
                                        // you can see nothing about Set of traders here
					stocks.addEntity(stockBeanItem.getBean());
				}
				stockItem = stocks.getItem( stockTableItem.getItemProperty("symbol").toString() );
				
				Set<Stock> stockSet = (Set<Stock>) traderItem.getItemProperty("stocks").getValue(); // traderItem is an Item object of particular trafer
				stockSet.add(stockItem.getEntity());
				traderItem.getItemProperty("stocks").setValue(stockSet);

After that I got a new row in stock row in stock db table and a new linking in trader_stock db table.

Hope it helps!

3

thank for your reply.

my problem is, that i could not delete an Relation between these two entities.
and my first try was with a manytomany relation with association class, so that there is an association entity and the mappings are onetomany and manytoone.

but i have decided to start with a simpler way and tried manytomany mapping. but the problem is just the same. java.util.concurrentmodification exception or jpacontainer deletes nothing! :frowning:

thank you!