Java protobuf uses lower camel for all field names. When using reflection to find the generic type of repeated fields, can't use the user specified formats for field name conversion. (#1119)

proto/src/main/java/com/google/gson/protobuf/ProtoTypeAdapter.java

@@ -19,7 +19,6 @@ package com.google.gson.protobuf;
 import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.common.base.CaseFormat;
-import com.google.common.base.Converter;
 import com.google.common.collect.MapMaker;
 import com.google.gson.JsonArray;
 import com.google.gson.JsonDeserializationContext;
@@ -94,7 +93,8 @@ public class ProtoTypeAdapter
     private final Set<Extension<FieldOptions, String>> serializedNameExtensions;
     private final Set<Extension<EnumValueOptions, String>> serializedEnumValueExtensions;
     private EnumSerialization enumSerialization;
-    private Converter<String, String> fieldNameSerializationFormat;
+    private CaseFormat protoFormat;
+    private CaseFormat jsonFormat;
 
     private Builder(EnumSerialization enumSerialization, CaseFormat fromFieldNameFormat,
         CaseFormat toFieldNameFormat) {
@@ -126,7 +126,8 @@ public class ProtoTypeAdapter
      */
     public Builder setFieldNameSerializationFormat(CaseFormat fromFieldNameFormat,
         CaseFormat toFieldNameFormat) {
-      fieldNameSerializationFormat = fromFieldNameFormat.converterTo(toFieldNameFormat);
+      this.protoFormat = fromFieldNameFormat;
+      this.jsonFormat = toFieldNameFormat;
       return this;
     }
 
@@ -174,7 +175,7 @@ public class ProtoTypeAdapter
     }
 
     public ProtoTypeAdapter build() {
-      return new ProtoTypeAdapter(enumSerialization, fieldNameSerializationFormat,
+      return new ProtoTypeAdapter(enumSerialization, protoFormat, jsonFormat,
           serializedNameExtensions, serializedEnumValueExtensions);
     }
   }
@@ -195,16 +196,19 @@ public class ProtoTypeAdapter
       new MapMaker().makeMap();
 
   private final EnumSerialization enumSerialization;
-  private final Converter<String, String> fieldNameSerializationFormat;
+  private final CaseFormat protoFormat;
+  private final CaseFormat jsonFormat;
   private final Set<Extension<FieldOptions, String>> serializedNameExtensions;
   private final Set<Extension<EnumValueOptions, String>> serializedEnumValueExtensions;
 
   private ProtoTypeAdapter(EnumSerialization enumSerialization,
-      Converter<String, String> fieldNameSerializationFormat,
+      CaseFormat protoFormat,
+      CaseFormat jsonFormat,
       Set<Extension<FieldOptions, String>> serializedNameExtensions,
       Set<Extension<EnumValueOptions, String>> serializedEnumValueExtensions) {
     this.enumSerialization = enumSerialization;
-    this.fieldNameSerializationFormat = fieldNameSerializationFormat;
+    this.protoFormat = protoFormat;
+    this.jsonFormat = jsonFormat;
     this.serializedNameExtensions = serializedNameExtensions;
     this.serializedEnumValueExtensions = serializedEnumValueExtensions;
   }
@@ -284,8 +288,9 @@ public class ProtoTypeAdapter
               protoBuilder.setField(fieldDescriptor, fieldValue);
             } else if (fieldDescriptor.isRepeated()) {
               // If the type is an array, then we have to grab the type from the class.
+              // protobuf java field names are always lower camel case
               String protoArrayFieldName =
-                  fieldNameSerializationFormat.convert(fieldDescriptor.getName()) + "_";
+                  protoFormat.to(CaseFormat.LOWER_CAMEL, fieldDescriptor.getName()) + "_";
               Field protoArrayField = protoClass.getDeclaredField(protoArrayFieldName);
               Type protoArrayFieldType = protoArrayField.getGenericType();
               fieldValue = context.deserialize(jsonElement, protoArrayFieldType);
@@ -325,7 +330,7 @@ public class ProtoTypeAdapter
         return options.getExtension(extension);
       }
     }
-    return fieldNameSerializationFormat.convert(defaultName);
+    return protoFormat.to(jsonFormat, defaultName);
   }
 
   /**

proto/src/main/protobuf/bag.proto

@@ -24,6 +24,11 @@ message SimpleProto {
   optional int32 count = 2;
 }
 
+message ProtoWithDifferentCaseFormat {
+  repeated string name_that_tests_case_format = 1;
+  optional string another_field = 2;
+}
+
 message ProtoWithRepeatedFields {
   repeated int64 numbers = 1;
   repeated SimpleProto simples = 2;

proto/src/test/java/com/google/gson/protobuf/functional/ProtosWithComplexAndRepeatedFieldsTest.java

@@ -15,10 +15,13 @@
  */
 package com.google.gson.protobuf.functional;
 
+import com.google.common.base.CaseFormat;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
+import com.google.gson.JsonObject;
 import com.google.gson.protobuf.ProtoTypeAdapter;
 import com.google.gson.protobuf.ProtoTypeAdapter.EnumSerialization;
+import com.google.gson.protobuf.generated.Bag.ProtoWithDifferentCaseFormat;
 import com.google.gson.protobuf.generated.Bag.ProtoWithRepeatedFields;
 import com.google.gson.protobuf.generated.Bag.SimpleProto;
 import com.google.protobuf.GeneratedMessage;
@@ -32,6 +35,7 @@ import junit.framework.TestCase;
  */
 public class ProtosWithComplexAndRepeatedFieldsTest extends TestCase {
   private Gson gson;
+  private Gson upperCamelGson;
 
   @Override
   protected void setUp() throws Exception {
@@ -43,6 +47,14 @@ public class ProtosWithComplexAndRepeatedFieldsTest extends TestCase {
                     .setEnumSerialization(EnumSerialization.NUMBER)
                     .build())
             .create();
+    upperCamelGson =
+        new GsonBuilder()
+            .registerTypeHierarchyAdapter(
+                GeneratedMessage.class, ProtoTypeAdapter.newBuilder()
+                    .setFieldNameSerializationFormat(
+                        CaseFormat.LOWER_UNDERSCORE, CaseFormat.UPPER_CAMEL)
+                    .build())
+            .create();
   }
 
   public void testSerializeRepeatedFields() {
@@ -67,4 +79,23 @@ public class ProtosWithComplexAndRepeatedFieldsTest extends TestCase {
     assertEquals("bar", proto.getSimples(0).getMsg());
     assertEquals(7, proto.getSimples(1).getCount());
   }
+
+  public void testSerializeDifferentCaseFormat() {
+    final ProtoWithDifferentCaseFormat proto =
+      ProtoWithDifferentCaseFormat.newBuilder()
+        .setAnotherField("foo")
+        .addNameThatTestsCaseFormat("bar")
+        .build();
+    final JsonObject json = upperCamelGson.toJsonTree(proto).getAsJsonObject();
+    assertEquals("foo", json.get("AnotherField").getAsString());
+    assertEquals("bar", json.get("NameThatTestsCaseFormat").getAsJsonArray().get(0).getAsString());
+  }
+
+  public void testDeserializeDifferentCaseFormat() {
+    final String json = "{NameThatTestsCaseFormat:['bar'],AnotherField:'foo'}";
+    ProtoWithDifferentCaseFormat proto =
+      upperCamelGson.fromJson(json, ProtoWithDifferentCaseFormat.class);
+    assertEquals("foo", proto.getAnotherField());
+    assertEquals("bar", proto.getNameThatTestsCaseFormat(0));
+  }
 }