Re: Model map with enum as a key

[Bas Gooren]

Hi!

In your first code example you are binding the property model to your
config map, using a string key for lookup (“VALUE1”).
Since generics in java is mostly syntactic sugar, I think the PropertyModel
reads & writes from your config map using a String key.
This is why hibernate complains: the map contains a String key instead of
an Enum.

We use a specialized MapKeyModel in our apps for this:

---

import java.util.Map;

import org.apache.wicket.model.IModel;

public class MapKeyModel<K, V> implements IModel<V>
{
    private final IModel<Map<K, V>> mapModel;
    private final K key;

    public static <K, V> MapKeyModel<K, V> of( IModel<Map<K, V>> mapModel,
K key )
    {
        return new MapKeyModel<K, V>( mapModel, key );
    }

    public MapKeyModel( IModel<Map<K, V>> mapModel, K key )
    {
        this.mapModel = mapModel;
        this.key = key;
    }

    @Override
    public V getObject()
    {
        Map<K, V> map = mapModel.getObject();

        return map.get( key );
    }

    @Override
    public void setObject( V object )
    {
        Map<K, V> map = mapModel.getObject();

        map.put( key, object );
    }

    @Override
    public void detach()
    {
        mapModel.detach();
    }

}

---

Met vriendelijke groet,
Kind regards,

Bas Gooren

Op 4 februari 2019 bij 13:51:28, Zbynek Vavros (zbynekvav...@gmail.com)
schreef:

I got this class that has map with enums as keys:

public class MasterClass {

private Map<MyEnum, String> config = Maps.newHashMap();
}

enum is classic:

public enum MyEnum {
VALUE1,
VALUE2
}

now I would like to use one entry of this map as a model for TextField:

new RequiredTextField<>("componentId", new
PropertyModel<>(modelObject.getConfig(), "VALUE1")))

but when saved to DB Hibernate says the key is String and Enum is expected:
java.lang.ClassCastException: java.lang.String cannot be cast to
java.lang.Enum

Using ChainingModel or
Model.of(modelObject.getConfig().get(MyEnum.VALUE1))) causes the value not
to be bind at all.

I know I can use "side" property and fill this map manually in onSubmit
just before saving to DB but would like to avoid that.

Thanks