Combobox with BeanItemContainer and BeanFieldGroup throw Conversion exception - javabeans

Question

I make some test to see how can bind combobox to some bean property, but i got an exception: "ConversionException: Could not convert value to String at ..........."
My sample work ok with indexedContainer for combobox, but i have some trouble with BeanItem container.
What i have:
1. TestCountry, simple java bean for BeanItemContainer (i don't put here setter and getter or constructor for simplicity):
public class TestCountry implements Serializable {
private String name;
private String shortName;
}
instantiation of BeanItemContainer
BeanItemContainer<TestCountry> _data = new BeanItemContainer<TestCountry>(TestCountry.class);
_data.addItem(new TestCountry("Afganistan","AF"));
_data.addItem(new TestCountry("Albania","AL"));
bean filed group. Here TestBean is another bean with simple string property's ("firstName","phone","contry")
BeanFieldGroup<TestBean> binder = new BeanFieldGroup<TestBean>(TestBean.class);
combobox
ComboBox myCombo = new ComboBox("Select your country", _data);
essential code
binder.bind(myCombo, "country");
When i try to commit the binder i got an error about conversion problem to string. From what i understand reading books and vaadin api, BeanItemContainer uses the beans themselves as identifiers and (here may be wrong) binder use item identifier to bind property. So here is the problem, conversion from Bean to string.
I try'it to implement toString(), hash() and equals() on my TestCountry bean but without success. What can do to use BeanItemContainer in this scenario?
Thanks in advance!!

Answer 1

You let your Vaadin application try to save a Bean (TestCountry) as a String in your TestBean.
That's fine, but then you have to approach it a little bit different. You have two options. You either change your datamodel, so the TestBean looks like this:
TestBean
firstName - String
phone - String
country - TestCountry (1:n)
now the TestBean will have a TestCountry stored instead of a String and your ComboBox shouldnt throw any more errors
or
you dont fill your ComboBox with Beans, but with Country strings, so the Vaadin application knows the datatype that is selected and what to save in your TestBean.
myCombo.addItem(getStringOfCountryYouWantToAdd())
...
then if you bind your String property "country" to the ComboBox which only contains Strings now, the binder will now how and what to save into "country".