Add TypeAdapters for VKey objects (#2194)

GSON doesn't allow for clean (de)serialization of Class or Serializable
objects which we'll need for converting VKeys to/from JSON.

core/src/main/java/google/registry/model/adapters/ClassProcessingTypeAdapterFactory.java

@@ -0,0 +1,40 @@
+// Copyright 2023 The Nomulus Authors. 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 google.registry.model.adapters;
+
+import com.google.gson.Gson;
+import com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
+import com.google.gson.reflect.TypeToken;
+
+/**
+ * Adapter factory that allows for (de)serialization of Class objects in GSON.
+ *
+ * <p>GSON's built-in adapter for Class objects throws an exception, but there are situations where
+ * we want to (de)serialize these, such as in VKeys. This instructs GSON to look for our custom
+ * {@link ClassTypeAdapter} rather than the default.
+ */
+public class ClassProcessingTypeAdapterFactory implements TypeAdapterFactory {
+
+  @Override
+  @SuppressWarnings("unchecked")
+  public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) {
+    if (Class.class.isAssignableFrom(typeToken.getRawType())) {
+      // in this case, T is a class object
+      return (TypeAdapter<T>) new ClassTypeAdapter();
+    }
+    return null;
+  }
+}

core/src/main/java/google/registry/model/adapters/ClassTypeAdapter.java

@@ -0,0 +1,48 @@
+// Copyright 2023 The Nomulus Authors. 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 google.registry.model.adapters;
+
+import com.google.gson.TypeAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+import java.io.IOException;
+
+/**
+ * TypeAdapter for {@link Class} objects.
+ *
+ * <p>GSON's default adapter doesn't allow this, but we want to allow for (de)serialization of Class
+ * objects for containers like VKeys using the full name of the class.
+ */
+public class ClassTypeAdapter extends TypeAdapter<Class<?>> {
+
+  @Override
+  public void write(JsonWriter out, Class value) throws IOException {
+    out.value(value.getName());
+  }
+
+  @Override
+  public Class<?> read(JsonReader reader) throws IOException {
+    String stringValue = reader.nextString();
+    if (stringValue.equals("null")) {
+      return null;
+    }
+    try {
+      return Class.forName(stringValue);
+    } catch (ClassNotFoundException e) {
+      // this should not happen...
+      throw new RuntimeException(e);
+    }
+  }
+}

core/src/main/java/google/registry/model/adapters/SerializableJsonTypeAdapter.java

@@ -0,0 +1,38 @@
+// Copyright 2023 The Nomulus Authors. 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 google.registry.model.adapters;
+
+import google.registry.util.StringBaseTypeAdapter;
+import java.io.IOException;
+import java.io.Serializable;
+
+/**
+ * TypeAdapter for {@link Serializable} objects.
+ *
+ * <p>VKey keys (primary keys in SQL) are usually represented by either a long or a String. There
+ * are a couple situations (CursorId, HistoryEntryId) where the Serializable in question is a
+ * complex object, but we do not need to worry about (de)serializing those objects to/from JSON.
+ */
+public class SerializableJsonTypeAdapter extends StringBaseTypeAdapter<Serializable> {
+
+  @Override
+  protected Serializable fromString(String stringValue) throws IOException {
+    try {
+      return Long.parseLong(stringValue);
+    } catch (NumberFormatException e) {
+      return stringValue;
+    }
+  }
+}

core/src/main/java/google/registry/model/domain/DomainBase.java

@@ -128,14 +128,14 @@ public class DomainBase extends EppResource
   String tld;
 
   /** References to hosts that are the nameservers for the domain. */
-  @Transient Set<VKey<Host>> nsHosts;
+  @Expose @Transient Set<VKey<Host>> nsHosts;
 
   /** Contacts. */
-  VKey<Contact> adminContact;
+  @Expose VKey<Contact> adminContact;
 
-  VKey<Contact> billingContact;
+  @Expose VKey<Contact> billingContact;
-  VKey<Contact> techContact;
+  @Expose VKey<Contact> techContact;
-  VKey<Contact> registrantContact;
+  @Expose VKey<Contact> registrantContact;
 
   /** Authorization info (aka transfer secret) of the domain. */
   @Embedded

core/src/main/java/google/registry/persistence/VKey.java

@@ -57,7 +57,7 @@ public class VKey<T> extends ImmutableObject implements Serializable {
   // The primary key for the referenced entity.
   @Expose Serializable key;
 
-  Class<? extends T> kind;
+  @Expose Class<? extends T> kind;
 
   @SuppressWarnings("unused")
   VKey() {}

core/src/main/java/google/registry/tools/GsonUtils.java

@@ -21,11 +21,14 @@ import com.google.gson.TypeAdapterFactory;
 import com.google.gson.reflect.TypeToken;
 import com.google.gson.stream.JsonReader;
 import com.google.gson.stream.JsonWriter;
+import google.registry.model.adapters.ClassProcessingTypeAdapterFactory;
 import google.registry.model.adapters.CurrencyJsonAdapter;
+import google.registry.model.adapters.SerializableJsonTypeAdapter;
 import google.registry.util.CidrAddressBlock;
 import google.registry.util.CidrAddressBlock.CidrAddressBlockAdapter;
 import google.registry.util.DateTimeTypeAdapter;
 import java.io.IOException;
+import java.io.Serializable;
 import org.joda.money.CurrencyUnit;
 import org.joda.time.DateTime;
 
@@ -69,9 +72,11 @@ public class GsonUtils {
 
   public static Gson provideGson() {
     return new GsonBuilder()
-        .registerTypeAdapter(DateTime.class, new DateTimeTypeAdapter())
         .registerTypeAdapter(CidrAddressBlock.class, new CidrAddressBlockAdapter())
         .registerTypeAdapter(CurrencyUnit.class, new CurrencyJsonAdapter())
+        .registerTypeAdapter(DateTime.class, new DateTimeTypeAdapter())
+        .registerTypeAdapter(Serializable.class, new SerializableJsonTypeAdapter())
+        .registerTypeAdapterFactory(new ClassProcessingTypeAdapterFactory())
         .registerTypeAdapterFactory(new GsonPostProcessableTypeAdapterFactory())
         .excludeFieldsWithoutExposeAnnotation()
         .create();

core/src/test/java/google/registry/model/adapters/VKeyAdapterTest.java

@@ -0,0 +1,49 @@
+// Copyright 2023 The Nomulus Authors. 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 google.registry.model.adapters;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.gson.Gson;
+import google.registry.model.billing.BillingEvent;
+import google.registry.model.domain.Domain;
+import google.registry.persistence.VKey;
+import google.registry.tools.GsonUtils;
+import org.junit.jupiter.api.Test;
+
+/** Tests for {@link ClassTypeAdapter} and {@link SerializableJsonTypeAdapter}. */
+public class VKeyAdapterTest {
+
+  private static final Gson GSON = GsonUtils.provideGson();
+
+  @Test
+  void testVKeyConversion_string() {
+    VKey<Domain> vkey = VKey.create(Domain.class, "someRepoId");
+    String vkeyJson = GSON.toJson(vkey);
+    assertThat(vkeyJson)
+        .isEqualTo(
+            "{\"key\":\"someRepoId\",\"kind\":" + "\"google.registry.model.domain.Domain\"}");
+    assertThat(GSON.fromJson(vkeyJson, VKey.class)).isEqualTo(vkey);
+  }
+
+  @Test
+  void testVKeyConversion_number() {
+    VKey<BillingEvent> vkey = VKey.create(BillingEvent.class, 203L);
+    String vkeyJson = GSON.toJson(vkey);
+    assertThat(vkeyJson)
+        .isEqualTo("{\"key\":203,\"kind\":" + "\"google.registry.model.billing.BillingEvent\"}");
+    assertThat(GSON.fromJson(vkeyJson, VKey.class)).isEqualTo(vkey);
+  }
+}

core/src/test/java/google/registry/ui/server/console/ConsoleDomainGetActionTest.java

@@ -66,10 +66,14 @@ public class ConsoleDomainGetActionTest {
     assertThat(RESPONSE.getStatus()).isEqualTo(HttpStatusCodes.STATUS_CODE_OK);
     assertThat(RESPONSE.getPayload())
         .isEqualTo(
-            "{\"domainName\":\"exists.tld\",\"registrationExpirationTime\":"
+            "{\"domainName\":\"exists.tld\",\"adminContact\":{\"key\":\"3-ROID\",\"kind\":"
-                + "\"294247-01-10T04:00:54.775Z\",\"lastTransferTime\":\"null\",\"repoId\":"
+                + "\"google.registry.model.contact.Contact\"},\"techContact\":{\"key\":\"3-ROID\","
-                + "\"2-TLD\",\"currentSponsorRegistrarId\":\"TheRegistrar\",\"creationRegistrarId\""
+                + "\"kind\":\"google.registry.model.contact.Contact\"},\"registrantContact\":"
-                + ":\"TheRegistrar\",\"creationTime\":{\"creationTime\":"
+                + "{\"key\":\"3-ROID\",\"kind\":\"google.registry.model.contact.Contact\"},"
+                + "\"registrationExpirationTime\":\"294247-01-10T04:00:54.775Z\","
+                + "\"lastTransferTime\":\"null\",\"repoId\":\"2-TLD\","
+                + "\"currentSponsorRegistrarId\":\"TheRegistrar\",\"creationRegistrarId\":"
+                + "\"TheRegistrar\",\"creationTime\":{\"creationTime\":"
                 + "\"1970-01-01T00:00:00.000Z\"},\"lastEppUpdateTime\":\"null\",\"statuses\":"
                 + "[\"INACTIVE\"]}");
   }