AWS AppSync を使用して Amazon QLDB への GraphQL インターフェイスを構築する: パート 2

SELECT id FROM Person AS t BY id WHERE t.GovId = ?

SELECT Vehicle FROM Vehicle INNER JOIN VehicleRegistration AS r ON Vehicle.VIN = r.VIN WHERE r.Owners.PrimaryOwner.PersonId = ?

private String executeTransaction(List<Query> queries) {
  try (QldbSession qldbSession = createQldbSession()) {
    List<String> result = new ArrayList<String>();

    qldbSession.execute((ExecutorNoReturn) txn -> {
      for (Query q : queries) {
        LOGGER.info("Executing query: {}", q.query);
        String lastResult = result.size() > 0 ? result.get(result.size() - 1) : "";
        result.add(executeQuery(txn, q, lastResult));
      }
    }, (retryAttempt) -> LOGGER.info("Retrying due to OCC conflict..."));

    return result.get(result.size() - 1);
  } catch (QldbClientException e) {
    LOGGER.error("Unable to create QLDB session: {}", e.getMessage());
  }

  return "{}";
}

private String executeQuery(TransactionExecutor txn, Query query, String lastResult) {
  final List<IonValue> params = new ArrayList<IonValue>();
  query.getArgs().forEach((a) -> {
    LOGGER.debug("Adding arg {} to query", a);
    try {
      String arg = a.startsWith("$.") && !lastResult.isEmpty() ?
                       queryWithJmesPath(lastResult, a.substring(2)) : a;
      params.add(MAPPER.writeValueAsIonValue(arg));
    } catch (IOException e) {
      LOGGER.error("Could not write value as Ion: {}", a);
    }
  });

  // Execute the query and transform response to JSON string...
  List<String> json = new ArrayList<String>();
  txn.execute(query.getQuery(), params).iterator().forEachRemaining(r -> {
    String j = convertToJson(r.toPrettyString());
    json.add(j);
  });

  return json.toString();
}

private String queryWithJmesPath(String json, String jmesExpression)
            throws IOException {
  LOGGER.debug("Query with JMESPath: {} on {}", jmesExpression, json);

  JmesPath<JsonNode> jmespath = new JacksonRuntime();
  Expression<JsonNode> expression = jmespath.compile(jmesExpression);

  ObjectMapper om = new ObjectMapper();
  JsonNode input = om.readTree(json);

  return om.writeValueAsString(expression.search(input)).replaceAll("^\"|\"$", "");
}

type Query {
  ...
  vehiclesByOwner(govId:ID!):[Vehicle]
}

type Mutation {
  updateVehicleOwner(vin:ID!, govId:ID!):Boolean
  addSecondaryOwner(vin:ID!, govId:ID!):Boolean
}

schema {
  query: Query
  mutation: Mutation
}

{
  "version": "2017-02-28",
  "operation": "Invoke",
  "payload": {
    "action": "Query",
    "payload": [
      {
        "query": "SELECT id FROM Person AS t BY id WHERE t.GovId = ?",
        "args": [ "$ctx.args.govId" ]
      },
      {
        "query": "SELECT Vehicle FROM Vehicle INNER JOIN VehicleRegistration AS r ON Vehicle.VIN = r.VIN WHERE r.Owners.PrimaryOwner.PersonId = ?",
        "args": [ "$.[0].id" ]
      }
    ]
  }
}

query VehiclesByOwner {
  vehiclesByOwner(govId:"LOGANB486CG") {
    VIN
    Make
    Model
  }
}

{
  "data": {
    "vehiclesByOwner": [
      {
        "VIN": "KM8SRDHF6EU074761",
        "Make": "Tesla",
        "Model": "Model S"
      }
    ]
  }
}

  "version": "2017-02-28",
  "operation": "Invoke",
  "payload": {
    "action": "Query",
    "payload": [
      {
        "query": "SELECT id FROM Person AS t BY id WHERE t.GovId = ?",
        "args": [ "$ctx.args.govId" ]
      },
      {
        "query": "UPDATE VehicleRegistration AS v SET v.Owners.PrimaryOwner.PersonId = ? WHERE v.VIN = ?",
        "args": [ "$.[0].id", "$ctx.args.vin" ]
      }
    ]
  }
}

type Query {
  ...
  getOwnershipByHistory(vin:ID!, monthsAgo:Int):[History]
}

type History {
  id: ID!
  version: Int!
  txTime: AWSDateTime! # transaction timestamp
  txId: ID!            # transaction ID
  data: HistoryData
  hash: String!
}

union HistoryData = Person | Owner | Vehicle | VehicleRegistration

#set( $months = $util.defaultIfNull($ctx.args.monthsAgo, 3) )
#set( $currEpochTime = $util.time.nowEpochMilliSeconds() )
#set( $fromEpochTime = $currEpochTime - ($months * 30 * 24 * 60 * 60 * 1000) )
#set( $fromTime = $util.time.epochMilliSecondsToISO8601($fromEpochTime) )
{
  "version": "2017-02-28",
  "operation": "Invoke",
  "payload": {
    "action": "Query",
    "payload": [
      {
        "query": "SELECT id FROM VehicleRegistration AS t BY id WHERE t.VIN = ?",
        "args": [ "$ctx.args.vin" ]
      },
      {
        "query": "SELECT * FROM history(VehicleRegistration, `$fromTime`) AS h WHERE h.metadata.id = ?",
        "args": [ "$.[0].id" ]
      }
    ]
  }
}

#set( $result = $util.parseJson($ctx.result.result) )
#set( $history = [] )

#foreach($item in $result)
  #set( $data = $item.data )
  $util.qr($data.put("__typename", "VehicleRegistration"))
  #set( $h = {
    "id": "$item.metadata.id",
    "version": $item.metadata.version,
    "txTime": "$item.metadata.txTime",
    "txId": "$item.metadata.txId",
    "hash": "$item.hash",
    "data": $data
  } )
  $util.qr($history.add($h))
#end

$util.toJson($history)

query GetVehicleHistory {
  getOwnershipHistory(vin:"3HGGK5G53FM761765") {
    version
    txTime
    data {
      ... on VehicleRegistration {
        Owners {
          PrimaryOwner {
            FirstName
            LastName
          }
        }
      }
    }
  }
}

{
  "data": {
    "getOwnershipHistory": [
      {
        "version": 0,
        "txTime": "2020-01-30T16:11:00.549Z",
        "data": {
          "Owners": {
            "PrimaryOwner": {
              "FirstName": "Alexis",
              "LastName": "Pena"
            }
          }
        }
      },
      {
        "version": 1,
        "txTime": "2020-02-05T22:17:36.262Z",
        "data": {
          "Owners": {
            "PrimaryOwner": {
              "FirstName": "Brent",
              "LastName": "Logan"
            }
          }
        }
      }
    ]
  }
}