Test Box.getRelationEntities and related, add docs and enforce types.

Author: greenrobot-team

objectbox-java/src/main/java/io/objectbox/Box.java

@@ -642,19 +642,33 @@ public long[] internalGetRelationIds(int sourceEntityId, int relationId, long ke
         }
     }
 
-    public List<T> getRelationEntities(RelationInfo relationInfo, long id) {
+    /**
+     * Given a ToMany relation and the ID of a source entity gets the target entities of the relation from their box,
+     * for example {@code orderBox.getRelationEntities(Customer_.orders, customer.getId())}.
+     */
+    public List<T> getRelationEntities(RelationInfo<?, T> relationInfo, long id) {
         return internalGetRelationEntities(relationInfo.sourceInfo.getEntityId(), relationInfo.relationId, id, false);
     }
 
-    public List<T> getRelationBacklinkEntities(RelationInfo relationInfo, long id) {
+    /**
+     * Given a ToMany relation and the ID of a target entity gets all source entities pointing to this target entity,
+     * for example {@code customerBox.getRelationEntities(Customer_.orders, order.getId())}.
+     */
+    public List<T> getRelationBacklinkEntities(RelationInfo<T, ?> relationInfo, long id) {
         return internalGetRelationEntities(relationInfo.sourceInfo.getEntityId(), relationInfo.relationId, id, true);
     }
 
-    public long[] getRelationIds(RelationInfo relationInfo, long id) {
+    /**
+     * Like {@link #getRelationEntities(RelationInfo, long)}, but only returns the IDs of the target entities.
+     */
+    public long[] getRelationIds(RelationInfo<?, T> relationInfo, long id) {
         return internalGetRelationIds(relationInfo.sourceInfo.getEntityId(), relationInfo.relationId, id, false);
     }
 
-    public long[] getRelationBacklinkIds(RelationInfo relationInfo, long id) {
+    /**
+     * Like {@link #getRelationBacklinkEntities(RelationInfo, long)}, but only returns the IDs of the source entities.
+     */
+    public long[] getRelationBacklinkIds(RelationInfo<T, ?> relationInfo, long id) {
         return internalGetRelationIds(relationInfo.sourceInfo.getEntityId(), relationInfo.relationId, id, true);
     }
 

tests/objectbox-java-test/src/test/java/io/objectbox/relation/ToManyStandaloneTest.java

@@ -16,15 +16,14 @@
 
 package io.objectbox.relation;
 
+import io.objectbox.Cursor;
+import io.objectbox.InternalAccess;
 import org.junit.Test;
 
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 
-import io.objectbox.Cursor;
-import io.objectbox.InternalAccess;
-
 import static org.junit.Assert.*;
 
 /**
@@ -62,10 +61,6 @@ public void testGet() {
         customer = customerBox.get(customer.getId());
         final ToMany<Order> toMany = customer.getOrdersStandalone();
 
-        //        RelationInfo<Order> info = Customer_.ordersStandalone;
-        //        int sourceEntityId = info.sourceInfo.getEntityId();
-        //        assertEquals(2, orderBox.internalGetRelationEntities(sourceEntityId, info.relationId, customer.getId()).size());
-
         assertGetOrder1And2(toMany);
     }
 
@@ -92,6 +87,60 @@ public void run() {
         });
     }
 
+    @Test
+    public void testGetRelationEntitiesAndIds() {
+        Customer customer = putCustomerWithOrders(2);
+        putOrder(null, "order3"); // without customer
+        Customer customerNoOrders = putCustomer();
+
+        // customer with orders
+        long customerId = customer.getId();
+        List<Order> ordersActual = orderBox.getRelationEntities(Customer_.ordersStandalone, customerId);
+        assertEquals(2, ordersActual.size());
+        assertEquals("order1", ordersActual.get(0).getText());
+        assertEquals("order2", ordersActual.get(1).getText());
+
+        long[] orderIdsActual = orderBox.getRelationIds(Customer_.ordersStandalone, customerId);
+        assertEquals(2, orderIdsActual.length);
+        assertEquals(ordersActual.get(0).getId(), orderIdsActual[0]);
+        assertEquals(ordersActual.get(1).getId(), orderIdsActual[1]);
+
+        // customer without orders
+        long customerNoOrdersId = customerNoOrders.getId();
+        List<Order> noOrdersActual = orderBox.getRelationEntities(Customer_.ordersStandalone, customerNoOrdersId);
+        assertEquals(0, noOrdersActual.size());
+
+        long[] noOrderIdsActual = orderBox.getRelationIds(Customer_.ordersStandalone, customerNoOrdersId);
+        assertEquals(0, noOrderIdsActual.length);
+    }
+
+    @Test
+    public void testGetRelationBacklinkEntitiesAndIds() {
+        Customer customer = putCustomerWithOrders(2);
+        Order order1 = customer.getOrdersStandalone().get(0);
+        putCustomer(); // without orders
+        Order orderNoCustomer = putOrder(null, "order3");
+
+        // order with customer
+        long order1Id = order1.getId();
+        List<Customer> customersActual = customerBox.getRelationBacklinkEntities(Customer_.ordersStandalone, order1Id);
+        assertEquals(1, customersActual.size());
+        assertEquals(customer.getId(), customersActual.get(0).getId());
+
+        long[] customerIdsActual = customerBox.getRelationBacklinkIds(Customer_.ordersStandalone, order1Id);
+        assertEquals(1, customerIdsActual.length);
+        assertEquals(customer.getId(), customerIdsActual[0]);
+
+        // order without customer
+        long orderNoCustomerId = orderNoCustomer.getId();
+        List<Customer> noCustomersActual = customerBox
+                .getRelationBacklinkEntities(Customer_.ordersStandalone, orderNoCustomerId);
+        assertEquals(0, noCustomersActual.size());
+
+        long[] noCustomerIdsActual = customerBox.getRelationBacklinkIds(Customer_.ordersStandalone, orderNoCustomerId);
+        assertEquals(0, noCustomerIdsActual.length);
+    }
+
     @Test
     public void testReset() {
         Customer customer = putCustomerWithOrders(2);