joins based on joins

curiosities · Jun 26, 2015 · 9f9422c · 9f9422c
1 parent 7e09203
commit 9f9422c
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Showing 2 changed files with 41 additions and 6 deletions.
diff --git a/DaoCore/src/de/greenrobot/dao/query/QueryBuilder.java b/DaoCore/src/de/greenrobot/dao/query/QueryBuilder.java
@@ -135,7 +135,7 @@ public <J> Join<T, J> join(Class<J> destinationEntityClass, Property destination
     public <J> Join<T, J> join(Property sourceProperty, Class<J> destinationEntityClass) {
         AbstractDao<J, ?> destinationDao = (AbstractDao<J, ?>) dao.getSession().getDao(destinationEntityClass);
         Property destinationProperty = destinationDao.getPkProperty();
-        return addJoin(sourceProperty, destinationDao, destinationProperty);
+        return addJoin(tablePrefix, sourceProperty, destinationDao, destinationProperty);
     }
 
     /**
@@ -144,13 +144,25 @@ public <J> Join<T, J> join(Property sourceProperty, Class<J> destinationEntityCl
      */
     public <J> Join<T, J> join(Property sourceProperty, Class<J> destinationEntityClass, Property destinationProperty) {
         AbstractDao<J, ?> destinationDao = (AbstractDao<J, ?>) dao.getSession().getDao(destinationEntityClass);
-        return addJoin(sourceProperty, destinationDao, destinationProperty);
+        return addJoin(tablePrefix, sourceProperty, destinationDao, destinationProperty);
     }
 
-    private <J> Join<T, J> addJoin(Property sourceProperty,
-                                   AbstractDao<J, ?> destinationDao, Property destinationProperty) {
+    /**
+     * Expands the query to another entity type by using a JOIN. The given sourceJoin's property is used to match the
+     * given destinationProperty of the given destinationEntity. Note that destination entity of the given join is used
+     * as the source for the new join to add. In this way, it is possible to compose complex "join of joins" across
+     * several entities if required.
+     */
+    public <J> Join<T, J> join(Join<?, T> sourceJoin, Property sourceProperty, Class<J> destinationEntityClass,
+                               Property destinationProperty) {
+        AbstractDao<J, ?> destinationDao = (AbstractDao<J, ?>) dao.getSession().getDao(destinationEntityClass);
+        return addJoin(sourceJoin.tablePrefix, sourceProperty, destinationDao, destinationProperty);
+    }
+
+    private <J> Join<T, J> addJoin(String sourceTablePrefix, Property sourceProperty, AbstractDao<J, ?> destinationDao,
+                                   Property destinationProperty) {
         String joinTablePrefix = "J" + (joins.size() + 1);
-        Join<T, J> join = new Join<T, J>(tablePrefix, sourceProperty, destinationDao, destinationProperty,
+        Join<T, J> join = new Join<T, J>(sourceTablePrefix, sourceProperty, destinationDao, destinationProperty,
                 joinTablePrefix);
         joins.add(join);
         return join;

diff --git a/DaoTest/src/de/greenrobot/daotest/query/JoinTest.java b/DaoTest/src/de/greenrobot/daotest/query/JoinTest.java
@@ -87,6 +87,28 @@ public void testJoinMixedParameterValues() {
         assertEquals("entity-6", entities.get(1).getSimpleString());
     }
 
+    public void testJoinOfJoin() {
+        prepareData();
+        List<RelationEntity> relationEntities = relationEntityDao.loadAll();
+        relationEntities.get(2).setParent(relationEntities.get(4));
+        relationEntities.get(3).setParent(relationEntities.get(5));
+        relationEntities.get(7).setParent(relationEntities.get(5));
+        relationEntityDao.updateInTx(relationEntities);
+
+        QueryBuilder<RelationEntity> queryBuilder = relationEntityDao.queryBuilder();
+        Join<RelationEntity, RelationEntity> join1 =
+                queryBuilder.join(RelationEntityDao.Properties.ParentId, RelationEntity.class);
+        queryBuilder.join(join1, RelationEntityDao.Properties.TestIdNotNull, TestEntity.class, Properties.Id)
+                .where(Properties.SimpleInt.lt(6));
+
+        Query<RelationEntity> query = queryBuilder.build();
+        RelationEntity entity = query.uniqueOrThrow();
+        assertEquals(relationEntities.get(2).getSimpleString(), entity.getSimpleString());
+
+        query.setParameter(0, 99);
+        assertEquals(3, query.list().size());
+    }
+
     public void testJoinDelete() {
         prepareData();
         QueryBuilder<RelationEntity> queryBuilder = createQueryBuilder(5);
@@ -114,14 +136,15 @@ public void testJoinCount() {
 
     private void prepareData() {
         List<TestEntity> targetEntities = new ArrayList<TestEntity>();
-        List<RelationEntity> entities = new ArrayList<RelationEntity>();
         for (int i = 0; i < 10; i++) {
             TestEntity testEntity = new TestEntity();
             testEntity.setSimpleInt(i + 1);
             testEntity.setSimpleStringNotNull("string-" + (i + 1));
             targetEntities.add(testEntity);
         }
         testEntityDao.insertInTx(targetEntities);
+
+        List<RelationEntity> entities = new ArrayList<RelationEntity>();
         for (int i = 0; i < 10; i++) {
             RelationEntity entity = new RelationEntity();
             entity.setSimpleString("entity-" + (i + 1));