library/src/main/java/org/apache/apex/malhar/lib/appdata/schemas/SchemaResultSerializer.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 com.datatorrent.lib.appdata.schemas;

import org.codehaus.jettison.json.JSONArray;
import org.codehaus.jettison.json.JSONException;
import org.codehaus.jettison.json.JSONObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.datatorrent.lib.appdata.query.serde.CustomMessageSerializer;

/**
 * This is the serializer class for {@link SchemaResult} objects.
 * @since 3.0.0
 */
public class SchemaResultSerializer implements CustomMessageSerializer
{
  /**
   * This constructor is required by the {@link CustomMessageSerializer} interface.
   */
  public SchemaResultSerializer()
  {
    //Do nothing
  }

  @Override
  public String serialize(Message message, ResultFormatter resultFormatter)
  {
    if (!(message instanceof SchemaResult)) {
      throw new IllegalArgumentException("Must receive a " + SchemaResult.class + " object.");
    }

    SchemaResult genericSchemaResult = (SchemaResult)message;

    StringBuilder sb = new StringBuilder();

    logger.debug("result {}", genericSchemaResult);
    logger.debug("result id {}", genericSchemaResult.getId());
    logger.debug("result type {}", genericSchemaResult.getType());

    sb.append("{\"").append(Result.FIELD_ID).append("\":\"").append(genericSchemaResult.getId())
        .append("\",\"").append(Result.FIELD_TYPE).append("\":\"").append(genericSchemaResult.getType())
        .append("\",\"").append(Result.FIELD_DATA).append("\":");

    JSONArray schemaArray = new JSONArray();

    for (Schema schema : genericSchemaResult.getGenericSchemas()) {
      try {
        schemaArray.put(new JSONObject(schema.getSchemaJSON()));
      } catch (JSONException ex) {
        throw new RuntimeException(ex);
      }
    }

    sb.append(schemaArray.toString()).append("}");

    return sb.toString();
  }

  private static final Logger logger = LoggerFactory.getLogger(SchemaResultSerializer.class);
}