How to data bind with a MultiSelectComboBox

Flow
1

After many hours, I was finally able to bind with a Select<…> using bind.withConverter. But I am stumped on how to bind with a MultiSelectComboBox.

I have a person document(MongoDB).

class Person {
  String id;
   :
}

and a Practice document.

class Practice {
  private List<Person> attendees;
  :
}

My edit form has the following defined:

Binder<Practice> binder = new BeanValidationBinder<>(Practice.class);

MultiSelectComboBox<Person> attendees = new MultiSelectComboBox<>();

binder.forField(attendees)
    .withConverter(new StringToPersonConverter(personService))
    .bind(Practice::getAttendees, Practice::setAttendees);

Finally, my StringToPersonConverter

public class StringToPersonConverter implements Converter<Set<Person>, String> {
    PersonService personService;

    public StringToPersonConverter(PersonService personService) {
        this.personService = personService;
    }

    @Override
    public Result<String> convertToModel(Set<Person> people, ValueContext valueContext) {
        return Result.ok(String.join(",", people.stream()
            .map(Person::getId)
            .collect(Collectors.toSet())));
    }

    @Override
    public Set<Person> convertToPresentation(String personId, ValueContext valueContext) {
        if (StringUtils.isNotBlank(personId)) {
            // what now?
            // return personService.getAll(personId);
        }
        return null;
    }
}

I’m probably way off with my approach. I sure could use some help. The tutorial and javadoc were not much help. I even looked at StringToUuidConverter just to get some hints. My converter is way off, I’m sure.

Any help would greatly appreciated. Thanks!

2

I’ve got the feeling you are doing something weirdly :sweat_smile: you don’t need the converter at all.

Normally it’s done like this:

Bean with Set :white_check_mark:
MultiSelect… :white_check_mark:
select.setItems(service.loadData()) :exclamation:
select.setItemLabel… :exclamation:
binder.forField(select) get/setAttendees :white_check_mark:

3

My first mistake was in my Practice class. Should have been:

class Practice {
  private Set<String> attendees;
  :
}

I want to store a set of Person IDs, which are Strings in MongoDB. From there, I just need custom renders and such. And I think you’re right, don’t need a converter, from what I can see now that I’ve changed from Person to String.

4

After a super late night and early morning coding session, I got it working.
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