IterableTranslator.java

IterableTranslator.java

protected Collection<Object> createCollection(Type type)
{
   // support reusing existing implementations 
   if (datastore.refresh != null)
   {
        @SuppressWarnings("unchecked")
	Collection<Object> result = (Collection<Object>) datastore.refresh;
	datastore.refresh = null;
	return result;
    }
    else 
    {

      if (type instanceof ParameterizedType) 
      {
        ParameterizedType t = (ParameterizedType) type;
        Class<?> rawType = (Class<?>) t.getRawType();


        if (Set.class.isAssignableFrom(rawType)) 
        {
          return new HashSet<Object>();
        }
      }

      return new ArrayList<Object>();
     }
}

SetPersistenceTest.java

package com.google.code.twig;

import com.google.code.twig.annotation.AnnotationObjectDatastore;
import com.google.code.twig.annotation.Id;
import org.junit.Test;

import java.util.HashSet;
import java.util.Set;

import static org.hamcrest.CoreMatchers.equalTo;
import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;

/**
 * @author Miroslav Genov (mgenov@gmail.com)
 */
public class SetPersistenceTest extends LocalDatastoreTestCase {

  static class Foo {
    @Id
    private String key;

    private Set<String> items;
  }

  @Test
  public void emptySetIsLoadedWhenEmptySetIsPersisted() {

    ObjectDatastore datastore = new AnnotationObjectDatastore(true);

    Foo foo = new Foo();
    foo.key = "key1";
    foo.items = new HashSet<String>();

    datastore.store().instance(foo).now();

    datastore.disassociateAll();

    Foo existingFoo = datastore.load().type(Foo.class).id(foo.key).now();
    assertThat(existingFoo.items.size(),is(equalTo(0)));
  }
}