#764 Gson.Other for other/unknown fields

gson/src/org/immutables/gson/Gson.java

@@ -18,6 +18,7 @@
 import com.google.gson.FieldNamingPolicy;
 import com.google.gson.FieldNamingStrategy;
 import com.google.gson.GsonBuilder;
+import com.google.gson.JsonObject;
 import com.google.gson.annotations.SerializedName;
 import java.lang.annotation.Documented;
 import java.lang.annotation.ElementType;
@@ -175,4 +176,12 @@
   @Documented
   @Target(ElementType.METHOD)
   public @interface Ignore {}
+
+  /**
+   * Can be put on accessor of type {@link JsonObject} as catch all collection of all other fields,
+   * not mapped to declared attributes (i.e. unknown).
+   */
+  @Documented
+  @Target(ElementType.METHOD)
+  public @interface Other {}
 }

gson/test/org/immutables/gson/adapter/GsonFeaturesTest.java

@@ -20,7 +20,9 @@
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.JsonElement;
+import com.google.gson.JsonNull;
 import com.google.gson.JsonObject;
+import com.google.gson.JsonPrimitive;
 import java.util.Map;
 import java.util.Set;
 import org.junit.Test;
@@ -32,6 +34,7 @@ public class GsonFeaturesTest {
       .serializeNulls()
       .registerTypeAdapterFactory(new GsonAdaptersSimple())
       .registerTypeAdapterFactory(new GsonAdaptersUnsimple())
+      .registerTypeAdapterFactory(new GsonAdaptersOtherAttributes())
       .create();
 
   final Gson gsonDefault = new GsonBuilder()
@@ -123,6 +126,17 @@ public void nullableContainersNames() {
     check(json).contains("\"m\":");
   }
 
+  @Test
+  public void otherAttributes() {
+    String json = "{\"a\":1,\"b\":\"B\",\"c\":true,\"d\":null}";
+    OtherAttributes o = gsonWithOptions.fromJson(json, OtherAttributes.class);
+
+    check(o.rest().get("c")).is(new JsonPrimitive(true));
+    check(o.rest().get("d")).is(JsonNull.INSTANCE);
+
+    check(gsonWithOptions.toJson(o)).is(json);
+  }
+
   private Set<String> keysIn(JsonObject json) {
     ImmutableMap.Builder<String, Object> builder = ImmutableMap.builder();
     for (Map.Entry<String, JsonElement> entry : json.entrySet()) {

gson/test/org/immutables/gson/adapter/OtherAttributes.java

@@ -0,0 +1,16 @@
+package org.immutables.gson.adapter;
+
+import com.google.gson.JsonObject;
+import org.immutables.gson.Gson;
+import org.immutables.value.Value;
+
+@Gson.TypeAdapters
+@Value.Immutable
+public interface OtherAttributes {
+  int a();
+
+  String b();
+
+  @Gson.Other
+  JsonObject rest();
+}

value-processor/src/org/immutables/value/processor/Gsons.generator

@@ -141,6 +141,9 @@ private static class [type.name]TypeAdapter[type.generics] extends TypeAdapter<[
   public final [a.secondaryElementType] [a.name]SecondaryTypeSample = null;
     [/if]
   [/for]
+  [for other = type.gsonOther][if other]
+  private final TypeAdapter<JsonElement> [other.name]TypeAdapter;
+  [/if][/for]
   [for a in allAttributes]
     [if a.requiresMarshalingAdapter and a.primitiveArrayType]
   private final TypeAdapter<[a.type]> [a.name]TypeAdapter;
@@ -171,6 +174,9 @@ private static class [type.name]TypeAdapter[type.generics] extends TypeAdapter<[
   [if type.generics]
     java.lang.reflect.Type['[]'] typeArguments = getTypeArguments(type);
   [/if]
+  [for other = type.gsonOther][if other]
+    this.[other.name]TypeAdapter = gson.getAdapter(JsonElement.class);
+  [/if][/for]
   [for a in allAttributes]
     [if a.requiresMarshalingAdapter]
     [getAdapterFromGson a false]
@@ -259,11 +265,21 @@ private void write[type.name](JsonWriter out, [type.typeAbstract] instance)
   [for a in type.marshaledAttributes]
   [generateMarshalAttributeValue type a]
   [/for]
+  [generateMarshalOther type]
   out.endObject();
 [/if]
 }
 [/template]
 
+[template generateMarshalOther Type type]
+[for other = type.gsonOther][if other]
+for (java.util.Map.Entry<String, JsonElement> other : instance.[other.names.get]().entrySet()) {
+  out.name(other.getKey());
+  [other.name]TypeAdapter.write(out, other.getValue());
+}
+[/if][/for]
+[/template]
+
 [template generateMarshalConstructorValue Type type Attribute a]
   [if a.optionalType]
 [a.type] [a.name]Optional = instance.[a.names.get]();
@@ -514,19 +530,27 @@ private [if type.generics.empty][if not type.unmarshaledAttributes]static[/if][/
   }
   [type.typeBuilder] builder = [castBuildStagedBuilder type][type.factoryBuilder]()[/castBuildStagedBuilder];
     [if type.unmarshaledAttributes]
+      [for other = type.gsonOther]
+        [if other]
+  JsonObject other = new JsonObject();
+        [/if]
   in.beginObject();
   while (in.hasNext()) {
-    eachAttribute(in, builder);
+    eachAttribute(in, builder[if other], other[/if]);
   }
   in.endObject();
+        [if other]
+  builder.[other.names.init](other);
+        [/if]
+      [/for]
     [else]
   in.skipValue();
     [/if]
   return builder.[type.names.build]();
 }
 [if type.unmarshaledAttributes]
 
-private void eachAttribute(JsonReader in, [type.typeBuilder] builder)
+private void eachAttribute(JsonReader in, [type.typeBuilder] builder[if type.gsonOther], JsonObject other[/if])
     throws IOException {
   String attributeName = in.nextName();
 [if type.gsonTypeAdapters.fieldNamingStrategy]
@@ -558,7 +582,13 @@ private void eachAttribute(JsonReader in, [type.typeBuilder] builder)
   default:
   }
 [/if]
+  [for other = type.gsonOther]
+    [if other]
+  other.add(attributeName, [other.name]TypeAdapter.read(in));
+    [else]
   in.skipValue();
+    [/if]
+  [/for]
 }
 [/if]
 [for s in type.unmarshaledAttributes]

value-processor/src/org/immutables/value/processor/meta/GsonMirrors.java

@@ -20,6 +20,8 @@
 public final class GsonMirrors {
   private GsonMirrors() {}
 
+  public static String JSON_OBJECT_TYPE = "com.google.gson.JsonObject";
+
   @Mirror.Annotation("org.immutables.gson.Gson.TypeAdapters")
   public @interface TypeAdapters {
     boolean metainfService() default true;
@@ -50,4 +52,7 @@ private GsonMirrors() {}
 
   @Mirror.Annotation("org.immutables.gson.Gson.Ignore")
   public @interface Ignore {}
+
+  @Mirror.Annotation("org.immutables.gson.Gson.Other")
+  public @interface GsonOther {}
 }

value-processor/src/org/immutables/value/processor/meta/ValueAttribute.java

@@ -289,6 +289,26 @@ public String getMarshaledName() {
     return names.raw;
   }
 
+  private @Nullable Boolean isGsonOther = null;
+
+  public boolean isGsonOther() {
+    if (isGsonOther == null) {
+      if (GsonOtherMirror.isPresent(element)) {
+        if (!isGenerateAbstract || !rawTypeName.equals(GsonMirrors.JSON_OBJECT_TYPE)) {
+          report().error(
+              "@Gson.Other attribute must be abstract accessor of type %s",
+              GsonMirrors.JSON_OBJECT_TYPE);
+          isGsonOther = false;
+        } else {
+          isGsonOther = true;
+        }
+      } else {
+        isGsonOther = false;
+      }
+    }
+    return isGsonOther;
+  }
+
   public boolean isForcedEmpty() {
     return !containingType.gsonTypeAdapters().emptyAsNulls();
   }

value-processor/src/org/immutables/value/processor/meta/ValueType.java

@@ -877,19 +877,19 @@ private FluentIterable<ValueAttribute> attributes() {
 
   public List<ValueAttribute> getMarshaledAttributes() {
     ImmutableList.Builder<ValueAttribute> builder = ImmutableList.builder();
-    for (ValueAttribute attribute : getImplementedAttributes()) {
-      if (!attribute.isJsonIgnore()) {
-        builder.add(attribute);
+    for (ValueAttribute a : getImplementedAttributes()) {
+      if (!a.isJsonIgnore() && !a.isGsonOther()) {
+        builder.add(a);
       }
     }
     return builder.build();
   }
 
   public List<ValueAttribute> getUnmarshaledAttributes() {
     ImmutableList.Builder<ValueAttribute> builder = ImmutableList.builder();
-    for (ValueAttribute attribute : getSettableAttributes()) {
-      if (!attribute.isJsonIgnore()) {
-        builder.add(attribute);
+    for (ValueAttribute a : getSettableAttributes()) {
+      if (!a.isJsonIgnore() && !a.isGsonOther()) {
+        builder.add(a);
       }
     }
     return builder.build();
@@ -1697,6 +1697,15 @@ public GsonTypeTokens getGsonTypeTokens() {
     }
     return gsonTypeTokens;
   }
+
+  public @Nullable ValueAttribute getGsonOther() {
+    for (ValueAttribute a : attributes) {
+      if (a.isGsonOther()) {
+        return a;
+      }
+    }
+    return null;
+  }
 
   private @Nullable TypeExtractor typeExtractor;