Problem bind Table @OneToMany

Vaadin 6 / 7 / 8
1

in the attachment i put the screenshot of one problem , when i bind the table with the entity Item , the foreign key from other entity in a relationship oneTomany the field USERDB shows this “model.userdb@5ee5…” that’s not the real data
15607.png

2

I assume that you’re using JPAContainer and the table is in non-editable mode. I think you need a Converter in this case.

Displaying a list of something in a Table cell is a bit problematic, as you can’t really have variable-height rows in a Table - in the following we just make it a comma-separated list:

// Have a persistent container
final JPAContainer<Country> countries =
    JPAContainerFactory.make(Country.class, "book-examples");
        
Table table = new Table(null, countries);
table.setVisibleColumns(new Object[]{"name", "people"});
table.setColumnHeaders("Country", "People");
table.setPageLength(table.size());

// Use converter to convert a Person set to a string
class PersonSetConverter implements Converter<String, Set<Person>> {
    @Override
    public Set<Person> convertToModel(String value,
        Class<? extends Set<Person>> targetType, Locale locale)
        throws com.vaadin.data.util.converter.Converter.ConversionException {
        return null; // Unused
    }

    @Override
    public String convertToPresentation(Set<Person> value,
        Class<? extends String> targetType, Locale locale)
        throws com.vaadin.data.util.converter.Converter.ConversionException {
        return value.stream().map(x->x.getName()).reduce((a,b) -> a+", "+b).orElse(""); // Java 8
    }

    @Override
    public Class<Set<Person>> getModelType() {
        return (Class<Set<Person>>) new HashSet<Person>().getClass().getSuperclass();
    }

    @Override
    public Class<String> getPresentationType() {
        return String.class;
    }
}        
table.setConverter("people", new PersonSetConverter());