Add fieldmask to JSON serialization functions (#537)

gax-httpjson/src/main/java/com/google/api/gax/httpjson/ApiMessage.java

@@ -31,19 +31,19 @@
 
 import com.google.api.core.BetaApi;
 import java.util.List;
-import java.util.Map;
-import java.util.Set;
 import javax.annotation.Nullable;
 
 /* An interface for message classes. */
 @BetaApi
 public interface ApiMessage {
-  /* For each field name in fieldNames, fetch that field's List<String> value. */
-  Map<String, List<String>> populateFieldsInMap(Set<String> fieldNames);
 
   /* Get the String value of a field in this message. */
   @Nullable
-  String getFieldStringValue(String fieldName);
+  Object getFieldValue(String fieldName);
+
+  /* List of names of fields to include in the serialized request body. */
+  @Nullable
+  List<String> getFieldMask();
 
   /* If this is a Request object, return the inner ApiMessage that represents the body
    * of the request; else return null. */

gax-httpjson/src/main/java/com/google/api/gax/httpjson/ApiMessageHttpRequestFormatter.java

@@ -33,11 +33,9 @@
 import com.google.api.pathtemplate.PathTemplate;
 import com.google.api.resourcenames.ResourceNameFactory;
 import com.google.auto.value.AutoValue;
-import com.google.gson.Gson;
+import com.google.common.collect.Lists;
 import com.google.gson.GsonBuilder;
-import com.google.gson.TypeAdapter;
-import com.google.gson.stream.JsonReader;
-import com.google.gson.stream.JsonWriter;
+import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
@@ -62,37 +60,14 @@ public abstract class ApiMessageHttpRequestFormatter<RequestT extends ApiMessage
   @Override
   public abstract PathTemplate getPathTemplate();
 
-  protected abstract Gson getRequestMarshaller();
-
   private static <RequestT extends ApiMessage> ApiMessageHttpRequestFormatter<RequestT> create(
-      final RequestT requestInstance,
       Set<String> queryParams,
       String resourceNameField,
       ResourceNameFactory resourceNameFactory,
       PathTemplate pathTemplate) {
 
-    final Gson baseGson = new GsonBuilder().create();
-
-    TypeAdapter requestTypeAdapter =
-        new TypeAdapter<RequestT>() {
-          @Override
-          public void write(JsonWriter out, RequestT value) {
-            baseGson.toJson(value, requestInstance.getClass(), out);
-          }
-
-          @Override
-          public RequestT read(JsonReader in) {
-            return null;
-          }
-        };
-
-    Gson requestMarshaller =
-        new GsonBuilder()
-            .registerTypeAdapter(requestInstance.getClass(), requestTypeAdapter)
-            .create();
-
     return new AutoValue_ApiMessageHttpRequestFormatter<>(
-        resourceNameField, resourceNameFactory, queryParams, pathTemplate, requestMarshaller);
+        resourceNameField, resourceNameFactory, queryParams, pathTemplate);
   }
 
   public static <RequestT extends ApiMessage>
@@ -104,7 +79,23 @@ ApiMessageHttpRequestFormatter.Builder<RequestT> newBuilder() {
   public Map<String, List<String>> getQueryParamNames(RequestT apiMessage) {
     Set<String> paramNames = getQueryParamNames();
     Map<String, List<String>> queryParams = new HashMap<>();
-    Map<String, List<String>> nullableParams = apiMessage.populateFieldsInMap(paramNames);
+    Map<String, List<String>> nullableParams = new HashMap<>();
+    for (String paramName : paramNames) {
+      Object paramValue = apiMessage.getFieldValue(paramName);
+      List<String> valueList;
+      if (paramValue == null) {
+        continue;
+      }
+      if (paramValue instanceof List) {
+        valueList = new ArrayList<>();
+        for (Object val : (List<Object>) paramValue) {
+          valueList.add(val.toString());
+        }
+      } else {
+        valueList = Lists.newArrayList(paramValue.toString());
+      }
+      nullableParams.put(paramName, valueList);
+    }
     Iterator<Map.Entry<String, List<String>>> iterator = nullableParams.entrySet().iterator();
     while (iterator.hasNext()) {
       Map.Entry<String, List<String>> pair = iterator.next();
@@ -118,10 +109,15 @@ public Map<String, List<String>> getQueryParamNames(RequestT apiMessage) {
   @Override
   public String getRequestBody(ApiMessage apiMessage) {
     ApiMessage body = apiMessage.getApiMessageRequestBody();
-    if (body != null) {
-      return getRequestMarshaller().toJson(body);
+    if (body == null) {
+      return null;
+    }
+    GsonBuilder requestMarshaller = new GsonBuilder().serializeNulls();
+    if (apiMessage.getFieldMask() != null) {
+      requestMarshaller.registerTypeAdapter(
+          body.getClass(), new FieldMaskedSerializer(apiMessage.getFieldMask()));
     }
-    return null;
+    return requestMarshaller.create().toJson(body);
   }
 
   @Override
@@ -131,29 +127,24 @@ public String getPath(RequestT apiMessage) {
   }
 
   private Map<String, String> getPathParams(RequestT apiMessage) {
-    String resourceNamePath = apiMessage.getFieldStringValue(getResourceNameField());
-    if (resourceNamePath == null) {
+    Object fieldValue = apiMessage.getFieldValue(getResourceNameField());
+    if (fieldValue == null) {
       throw new IllegalArgumentException(
           String.format(
               "Resource name field %s is null in message object.", getResourceNameField()));
     }
+    String resourceNamePath = fieldValue.toString();
     return getResourceNameFactory().parse(resourceNamePath).getFieldValuesMap();
   }
 
   public static class Builder<RequestT extends ApiMessage> {
-    private RequestT requestInstance;
     private String resourceNameField;
     private ResourceNameFactory resourceNameFactory;
     private Set<String> queryParams;
     private PathTemplate pathTemplate;
 
     private Builder() {}
 
-    public Builder<RequestT> setRequestInstance(RequestT requestInstance) {
-      this.requestInstance = requestInstance;
-      return this;
-    }
-
     public Builder<RequestT> setResourceNameField(String resourceNameField) {
       this.resourceNameField = resourceNameField;
       return this;
@@ -176,7 +167,7 @@ public Builder<RequestT> setQueryParams(Set<String> queryParams) {
 
     public ApiMessageHttpRequestFormatter<RequestT> build() {
       return ApiMessageHttpRequestFormatter.create(
-          requestInstance, queryParams, resourceNameField, resourceNameFactory, pathTemplate);
+          queryParams, resourceNameField, resourceNameFactory, pathTemplate);
     }
   }
 }

gax-httpjson/src/main/java/com/google/api/gax/httpjson/FieldMaskedSerializer.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2018 Google LLC
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google LLC nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package com.google.api.gax.httpjson;
+
+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.JsonSerializationContext;
+import com.google.gson.JsonSerializer;
+import java.lang.reflect.Type;
+import java.util.List;
+
+/** JSON Serializer for messages with a field mask to selectively serialize fields. */
+public class FieldMaskedSerializer implements JsonSerializer<ApiMessage> {
+  private final List<String> fieldMask;
+
+  public FieldMaskedSerializer(List<String> fieldMask) {
+    this.fieldMask = fieldMask;
+  }
+
+  @Override
+  public JsonElement serialize(
+      ApiMessage requestBody, Type typeOfSrc, JsonSerializationContext context) {
+    Gson gson = new GsonBuilder().serializeNulls().create();
+    if (fieldMask == null) {
+      return gson.toJsonTree(requestBody, typeOfSrc);
+    }
+    JsonObject jsonObject = new JsonObject();
+    for (String fieldName : fieldMask) {
+      Object fieldValue = requestBody.getFieldValue(fieldName);
+      if (fieldValue != null) {
+        jsonObject.add(fieldName, gson.toJsonTree(fieldValue, fieldValue.getClass()));
+      } else {
+        // TODO(andrealin): This doesn't distinguish between the non-existence of a field
+        // and a field value being null.
+        jsonObject.add(fieldName, JsonNull.INSTANCE);
+      }
+    }
+
+    return jsonObject;
+  }
+}