External type: also support, smoke test for standalone ToMany objectbox-java#239

Author: greenrobot-team

objectbox-java-api/src/main/java/io/objectbox/annotation/ExternalType.java

@@ -23,7 +23,7 @@
 import java.lang.annotation.Target;
 
 /**
- * Use to set the type of property in an external system (like another database).
+ * Sets the type of a property or the type of object IDs of a ToMany in an external system (like another database).
  * <p>
  * This is useful if there is no default mapping of the ObjectBox type to the type in the external system.
  * <p>

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

@@ -149,7 +149,7 @@ public PropertyBuilder indexMaxValueLength(int indexMaxValueLength) {
         }
 
         /**
-         * Set a {@link ExternalPropertyType} constant.
+         * Sets the {@link ExternalPropertyType} constant for this.
          *
          * @return this builder.
          */
@@ -261,6 +261,7 @@ public static class RelationBuilder extends PartBuilder {
         private final long relationUid;
         private final int targetEntityId;
         private final long targetEntityUid;
+        private int externalPropertyType;
 
         private RelationBuilder(FlatBufferBuilder fbb, String name, int relationId, long relationUid,
                                 int targetEntityId, long targetEntityUid) {
@@ -272,6 +273,17 @@ private RelationBuilder(FlatBufferBuilder fbb, String name, int relationId, long
             this.targetEntityUid = targetEntityUid;
         }
 
+        /**
+         * Sets the {@link ExternalPropertyType} constant for this.
+         *
+         * @return this builder.
+         */
+        public RelationBuilder externalType(int externalPropertyType) {
+            checkNotFinished();
+            this.externalPropertyType = externalPropertyType;
+            return this;
+        }
+
         @Override
         public int createFlatBufferTable(FlatBufferBuilder fbb) {
             int nameOffset = fbb.createString(name);
@@ -282,6 +294,9 @@ public int createFlatBufferTable(FlatBufferBuilder fbb) {
             ModelRelation.addId(fbb, relationIdOffset);
             int targetEntityIdOffset = IdUid.createIdUid(fbb, targetEntityId, targetEntityUid);
             ModelRelation.addTargetEntityId(fbb, targetEntityIdOffset);
+            if (externalPropertyType != 0) {
+                ModelRelation.addExternalType(fbb, externalPropertyType);
+            }
             return ModelRelation.endModelRelation(fbb);
         }
     }

tests/objectbox-java-test/src/main/java/io/objectbox/relation/Customer.java

@@ -22,6 +22,8 @@
 import io.objectbox.BoxStore;
 import io.objectbox.annotation.Backlink;
 import io.objectbox.annotation.Entity;
+import io.objectbox.annotation.ExternalPropertyType;
+import io.objectbox.annotation.ExternalType;
 import io.objectbox.annotation.Id;
 import io.objectbox.annotation.Index;
 
@@ -51,6 +53,10 @@ public class Customer implements Serializable {
 
     ToMany<Order> ordersStandalone = new ToMany<>(this, Customer_.ordersStandalone);
 
+    // Just smoke testing, also use UUID instead of the default Mongo ID
+    @ExternalType(ExternalPropertyType.UUID_VECTOR)
+    private ToMany<Order> toManyExternalId = new ToMany<>(this, Customer_.toManyExternalId);
+
     // Note: in a typical project the BoxStore field is added by the ObjectBox byte code transformer
     // https://docs.objectbox.io/relations#initialization-magic
     transient BoxStore __boxStore;
@@ -86,4 +92,8 @@ public List<Order> getOrders() {
     public ToMany<Order> getOrdersStandalone() {
         return ordersStandalone;
     }
+
+    public ToMany<Order> getToManyExternalId() {
+        return toManyExternalId;
+    }
 }

tests/objectbox-java-test/src/main/java/io/objectbox/relation/CustomerCursor.java

@@ -71,6 +71,7 @@ public long put(Customer entity) {
 
         checkApplyToManyToDb(entity.getOrders(), Order.class);
         checkApplyToManyToDb(entity.getOrdersStandalone(), Order.class);
+        checkApplyToManyToDb(entity.getToManyExternalId(), Order.class);
 
         return __assignedId;
     }

tests/objectbox-java-test/src/main/java/io/objectbox/relation/Customer_.java

@@ -129,4 +129,14 @@ public List<Order> getToMany(Customer customer) {
                 }
             }, 1);
 
+    /** To-many relation "toManyExternalId" to target entity "Order". */
+    public static final RelationInfo<Customer, Order> toManyExternalId = new RelationInfo<>(Customer_.__INSTANCE, Order_.__INSTANCE,
+            new ToManyGetter<Customer, Order>() {
+                @Override
+                public List<Order> getToMany(Customer entity) {
+                    return entity.getToManyExternalId();
+                }
+            },
+            2);
+
 }

tests/objectbox-java-test/src/main/java/io/objectbox/relation/MyObjectBox.java

@@ -20,6 +20,7 @@
 import io.objectbox.BoxStoreBuilder;
 import io.objectbox.ModelBuilder;
 import io.objectbox.ModelBuilder.EntityBuilder;
+import io.objectbox.model.ExternalPropertyType;
 import io.objectbox.model.PropertyFlags;
 import io.objectbox.model.PropertyType;
 
@@ -45,17 +46,22 @@ private static byte[] getModel() {
         ModelBuilder modelBuilder = new ModelBuilder();
         modelBuilder.lastEntityId(4, 5318696586219463633L);
         modelBuilder.lastIndexId(2, 8919874872236271392L);
-        modelBuilder.lastRelationId(1, 8943758920347589435L);
+        modelBuilder.lastRelationId(2, 297832184913930702L);
 
-        EntityBuilder entityBuilder;
-
-        entityBuilder = modelBuilder.entity("Customer");
+        EntityBuilder entityBuilder = modelBuilder.entity("Customer");
         entityBuilder.id(1, 8247662514375611729L).lastPropertyId(2, 7412962174183812632L);
         entityBuilder.property("_id", PropertyType.Long).id(1, 1888039726372206411L)
                 .flags(PropertyFlags.ID | PropertyFlags.ID_SELF_ASSIGNABLE);
         entityBuilder.property("name", PropertyType.String).id(2, 7412962174183812632L)
                 .flags(PropertyFlags.INDEXED).indexId(1, 5782921847050580892L);
+
         entityBuilder.relation("ordersStandalone", 1, 8943758920347589435L, 3, 6367118380491771428L);
+
+        // Note: there is no way to test external type mapping works here. Instead, verify passing a model with
+        // externalType(int) works.
+        entityBuilder.relation("toManyExternalId", 2, 297832184913930702L, 3, 6367118380491771428L)
+                .externalType(ExternalPropertyType.UuidVector);
+
         entityBuilder.entityDone();
 
 

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

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2025 ObjectBox Ltd. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.objectbox.relation;
+
+
+import org.junit.Test;
+
+
+import static org.junit.Assert.assertEquals;
+
+public class ExternalTypeTest extends AbstractRelationTest {
+
+    /**
+     * There is no way to test external type mapping works here. Instead, verify passing a model with
+     * {@link io.objectbox.ModelBuilder.RelationBuilder#externalType(int)} works (see {@link MyObjectBox}) and that
+     * there are no side effects for put and get.
+     */
+    @Test
+    public void standaloneToMany_externalType_putGetSmokeTest() {
+        Customer putCustomer = new Customer();
+        putCustomer.setName("Joe");
+        Order order = new Order();
+        order.setText("Order from Joe");
+        putCustomer.getToManyExternalId().add(order);
+        long customerId = customerBox.put(putCustomer);
+
+        Customer readCustomer = customerBox.get(customerId);
+        assertEquals(order.getText(), readCustomer.getToManyExternalId().get(0).getText());
+    }
+
+}