Google Cloud Datastore Dart example

gistfile1.dart

import 'dart:convert';

import 'configuration.dart';

import 'package:google_oauth2_client/google_oauth2_console.dart';
import 'package:google_datastore_v1beta2_api/datastore_v1beta2_api_client.dart' as client;
import 'package:google_datastore_v1beta2_api/datastore_v1beta2_api_console.dart' as console;

/**
 * Search for args[0] ID in datastore. Add new entity if search fails to locate
 * a matching entity.
 */
void main(List<String> args) {
  if(args.length == 0) {args = [''];}

  try {
    final console.Datastore datastore = getDatastore();
    String           id        = args[0].isEmpty ? '1' : args[0];
    String           txnHandle;
    List<client.Key> keys      = [buildKey('person', id)];

    datastore.datasets.beginTransaction(txnRequest(), Config.projectId)
      .then((client.BeginTransactionResponse txnResponse) {
        txnHandle = txnResponse.transaction;
        return datastore.datasets.lookup(lookupRequest(txnHandle, keys), Config.projectId);
      })
      .then((client.LookupResponse response) {
        response.found.forEach((client.EntityResult result) {
          print('Found: ${JSON.encode(result.entity.properties)}');
        });

        if (response.found.isEmpty) {
          final String timestamp     = new DateTime.now().toUtc().toIso8601String();
          final Map<String, client.Property> person =
            {'name'      : new client.Property.fromJson({'stringValue'   : 'Thomas Løcke'}),
             'website'   : new client.Property.fromJson({'stringValue'   : 'http://google.com/+ThomasLøcke'}),
             'timestamp' : new client.Property.fromJson({'dateTimeValue' : timestamp})};
          final client.Entity entity = new client.Entity.fromJson({})
                                              ..key = new client.Key.fromJson({'path' : [{'kind' : 'person'}]})
                                              ..properties = person;
          final client.CommitRequest request = new client.CommitRequest.fromJson({})
                                                ..transaction = txnHandle
                                                ..mutation = new client.Mutation.fromJson({})
                                                ..mutation.insertAutoId = [entity];

          datastore.datasets.commit(request, Config.projectId)
            .then((client.CommitResponse response) {
              id = response.mutationResult.insertAutoIdKeys.first.toJson()['path'][0]['id'];
              print('Inserted new entity with id ${id}');
            })
            .whenComplete(() {
              datastore.datasets.lookup(lookupRequest('', [buildKey('person', id)]), Config.projectId)
                .then((client.LookupResponse response) {
                  response.found.forEach((client.EntityResult result) {
                    print('Found new entity: ${JSON.encode(result.entity.properties)}');
                  });
                });
            });
        }
      }).catchError((error) => print('Datastore interaction failed with ${error}'));
  } catch(error) {
    print('Script failed with ${error}');
  }
}

client.Key buildKey(String kind, String id) => new client.Key.fromJson({'path' : [{'id' : '${id}', 'kind' : '${kind}'}]});

console.Datastore getDatastore() {
  final ComputeOAuth2Console oauthClient =
      new ComputeOAuth2Console(Config.projectNumber,
                               privateKey : Config.privateKey,
                               iss        : Config.serviceEmail,
                               scopes     : Config.scopes);

  return new console.Datastore(oauthClient)
                      ..makeAuthRequests = true;
}

client.LookupRequest lookupRequest(String txnHandle, List<client.Key> keys) {
  final client.LookupRequest lookupRequest = new client.LookupRequest.fromJson({})
                                                  ..keys = keys;

  if(txnHandle.isNotEmpty) {
    lookupRequest.readOptions = new client.ReadOptions.fromJson({'transaction' : txnHandle});
  }

  return lookupRequest;
}

client.BeginTransactionRequest txnRequest() => new client.BeginTransactionRequest.fromJson({});