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

import java.util.Collections;
import java.util.Map;

import com.google.common.base.Preconditions;
import com.google.common.collect.Maps;

/**
 * This is a base class which represents the basic functionality of all AppData queries.
 * @since 3.0.0
 */
public abstract class Query extends QRBase
{
  /**
   * The String that is used as a key in JSON requests to represent the shemaKeys.
   */
  public static final String FIELD_SCHEMA_KEYS = "schemaKeys";

  /**
   * The schemaKeys.
   */
  protected Map<String, String> schemaKeys;

  /**
   * No-arg constructor is required by some deserializers.
   */
  public Query()
  {
    //Do nothing
  }

  /**
   * Creates a query with the given id.
   * @param id The query id.
   */
  public Query(String id)
  {
    super(id);
  }

  /**
   * Creates a query with the given id and type.
   * @param id The query id.
   * @param type The type of the query.
   */
  public Query(String id, String type)
  {
    super(id, type);
  }

  /**
   * Creates a query with the given id, type, and schemaKeys.
   * @param id The query id.
   * @param type The type of the query.
   * @param schemaKeys The schemaKeys for the query.
   */
  public Query(String id, String type, Map<String, String> schemaKeys)
  {
    super(id, type);
    setSchemaKeys(schemaKeys);
  }

  /**
   * Creates a query with the given id, type, and countdown.
   * @param id The query id.
   * @param type The type of the query.
   * @param countdown The countdown for the query.
   */
  public Query(String id, String type, long countdown)
  {
    super(id, type, countdown);
  }

  /**
   * Creates a query with the given id, type, countdown, and schemaKeys.
   * @param id The query id.
   * @param type The type of the query.
   * @param countdown The countdown for the query.
   * @param schemaKeys The schemaKeys for the query.
   */
  public Query(String id, String type, long countdown, Map<String, String> schemaKeys)
  {
    super(id, type, countdown);
    setSchemaKeys(schemaKeys);
  }

  /**
   * Helper method to set schema keys and validate the schema keys.
   * @param schemaKeys The schemaKeys to sett and validate.
   */
  private void setSchemaKeys(Map<String, String> schemaKeys)
  {
    if (schemaKeys == null) {
      return;
    }

    for (Map.Entry<String, String> entry : schemaKeys.entrySet()) {
      Preconditions.checkNotNull(entry.getKey());
      Preconditions.checkNotNull(entry.getValue());
    }

    this.schemaKeys = Collections.unmodifiableMap(Maps.newHashMap(schemaKeys));
  }

  /**
   * Gets the schemaKeys for the query.
   * @return The schemaKeys for the query.
   */
  public Map<String, String> getSchemaKeys()
  {
    return schemaKeys;
  }
}