MoveModel.java

package scorekeep;

import com.amazonaws.services.dynamodbv2.AmazonDynamoDB;
import com.amazonaws.services.dynamodbv2.AmazonDynamoDBClientBuilder;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBQueryExpression;
import com.amazonaws.services.dynamodbv2.model.AttributeValue;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class MoveModel {
  /** AWS SDK credentials. */
  private AmazonDynamoDB client = AmazonDynamoDBClientBuilder.standard()
        .build();
  private DynamoDBMapper mapper = new DynamoDBMapper(client);
  private final SessionModel sessionModel = new SessionModel();
  private final GameModel gameModel = new GameModel();

  public void saveMove(Move move) throws SessionNotFoundException, GameNotFoundException {
    // check session
    String sessionId = move.getSession();
    String gameId = move.getGame();
    if (sessionModel.loadSession(sessionId) == null ) {
      throw new SessionNotFoundException(sessionId);
    }
    if (gameModel.loadGame(gameId) == null ) {
      throw new GameNotFoundException(gameId);
    }
    mapper.save(move);
  }

  public Move loadMove(String moveId) throws MoveNotFoundException {
    Move move = mapper.load(Move.class, moveId);
    if ( move == null ) {
      throw new MoveNotFoundException(moveId);
    }
    return move;
  }

  public List<Move> loadMoves(String sessionId, String gameId) throws SessionNotFoundException, GameNotFoundException {
    if ( sessionModel.loadSession(sessionId) == null ) {
      throw new SessionNotFoundException(sessionId);
    }
    if ( gameModel.loadGame(gameId) == null ) {
      throw new GameNotFoundException(gameId);
    }
    Map<String, AttributeValue> eav = new HashMap<String, AttributeValue>();
    eav.put(":val1", new AttributeValue().withS(gameId));

    Map<String, String> ean = new HashMap<String, String>();
    ean.put("#key1", "game");

    DynamoDBQueryExpression<Move> queryExpression = new DynamoDBQueryExpression<Move>()
    .withIndexName("game-index")
    .withExpressionAttributeValues(eav)
    .withExpressionAttributeNames(ean)
    .withKeyConditionExpression("#key1 = :val1")
    .withConsistentRead(false);

    List<Move> gameMoves = mapper.query(Move.class, queryExpression);
    return gameMoves;
  }

  public void deleteMove(String moveId) throws MoveNotFoundException {
    Move move = mapper.load(Move.class, moveId);
    if ( move == null ) {
      throw new MoveNotFoundException(moveId);
    }
    mapper.delete(move);
  }
}