Fix to-many relationships in JPAModule

When you tried to query a to-many relation it didn't produce a proper result.

Reproduction of the issue is found in JpaRelationshipRepositoryTestBase class.

I had to disable the QueryDSL tests because the QueryFactory for QueryDsl still
cannot handle to-many type of queries properly.

katharsis-jpa/src/main/java/io/katharsis/jpa/JpaModule.java

@@ -263,8 +263,13 @@ private Set<Class<?>> getRelatedResource(MetaEntity metaEntity) {
 		Set<Class<?>> relatedResourceClasses = new HashSet<>();
 		for (MetaAttribute attr : metaEntity.getAttributes()) {
 			if (attr.isAssociation()) {
-				Class<?> relType = attr.getType().getImplementationClass();
-
+				Class<?> relType = null;
+				if(attr.getType().isCollection()) {
+					relType = attr.getType().getElementType().getImplementationClass();
+				}
+				else {
+					relType = attr.getType().getImplementationClass();
+				}
 				// only include relations that are exposed as repositories
 				if (entityClasses.contains(relType)) {
 					relatedResourceClasses.add(relType);

katharsis-jpa/src/main/java/io/katharsis/jpa/internal/query/AbstractJpaQueryImpl.java

@@ -71,7 +71,12 @@ public AbstractJpaQueryImpl(MetaLookup metaLookup, EntityManager em, Class<?> en
 
 		MetaDataObject parentMeta = metaLookup.getMeta(entityClass).asDataObject();
 		MetaAttribute attrMeta = parentMeta.getAttribute(attrName);
-		this.meta = attrMeta.getType().asEntity();
+		if(attrMeta.getType().isCollection()) {
+			this.meta = attrMeta.getType().asCollection().getElementType().asEntity();
+		}
+		else {
+			this.meta = attrMeta.getType().asEntity();
+		}
 		this.clazz = (Class<T>) meta.getImplementationClass();
 
 		this.parentEntityClass = entityClass;

katharsis-jpa/src/test/java/io/katharsis/jpa/repository/JpaRelationshipRepositoryTestBase.java

@@ -1,9 +1,15 @@
 package io.katharsis.jpa.repository;
 
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Iterator;
+import java.util.List;
 
+import org.hamcrest.core.Is;
+import org.hamcrest.core.IsInstanceOf;
+import org.hamcrest.core.IsNot;
 import org.junit.Assert;
+import org.junit.Assume;
 import org.junit.Before;
 import org.junit.Test;
 import org.springframework.transaction.annotation.Transactional;
@@ -12,6 +18,7 @@
 import io.katharsis.jpa.model.RelatedEntity;
 import io.katharsis.jpa.model.TestEntity;
 import io.katharsis.jpa.query.AbstractJpaTest;
+import io.katharsis.jpa.query.querydsl.QuerydslQueryFactory;
 import io.katharsis.queryspec.FilterOperator;
 import io.katharsis.queryspec.FilterSpec;
 import io.katharsis.queryspec.QuerySpec;
@@ -146,4 +153,29 @@ public void testSetRelation() throws InstantiationException, IllegalAccessExcept
 		related = em.find(RelatedEntity.class, 101L);
 		Assert.assertNull(related.getTestEntity());
 	}
+
+	@Test
+	public void testGetManyRelation() {
+		//TODO fix for QueryDSL
+		Assume.assumeThat("QueryDSL still breaks on this, so ignore it for now",
+				queryFactory, IsNot.not(IsInstanceOf.instanceOf(QuerydslQueryFactory.class)));
+		TestEntity test = em.find(TestEntity.class, 1L);
+		Assert.assertThat(test.getManyRelatedValues().size(), Is.is(0));
+
+		repo.addRelations(test, Arrays.asList(101L,102L), TestEntity.ATTR_manyRelatedValues);
+		em.flush();
+		em.clear();
+		test = em.find(TestEntity.class, 1L);
+		Assert.assertThat(test.getManyRelatedValues().size(), Is.is(2));
+
+		QuerySpec querySpec = new QuerySpec(RelatedEntity.class);
+		Iterable<RelatedEntity> targets = repo.findManyTargets(1L, TestEntity.ATTR_manyRelatedValues, querySpec);
+		List<RelatedEntity> res = new ArrayList<>();
+		for (RelatedEntity relatedEntity : targets) {
+			res.add(relatedEntity);
+		}
+		Assert.assertThat(res.size(), Is.is(2));
+		Assert.assertThat(res.get(0).getId(), Is.is(101L));
+		Assert.assertThat(res.get(1).getId(), Is.is(102L));
+	}
 }