public async Task <List <Album> > QueryDataWithTransactionAsync(string projectId, string instanceId, string databaseId)
{
string connectionString = $"Data Source=projects/{projectId}/instances/{instanceId}/databases/{databaseId}";
var albums = new List <Album>();
using TransactionScope scope = new TransactionScope(TransactionScopeAsyncFlowOption.Enabled);
using var connection = new SpannerConnection(connectionString);
// Open the connection, making the implicitly created
// transaction read only when it connects to the outer
// transaction scope.
await connection.OpenAsReadOnlyAsync();
using var cmd = connection.CreateSelectCommand("SELECT SingerId, AlbumId, AlbumTitle FROM Albums");
// Read #1.
using (var reader = await cmd.ExecuteReaderAsync())
{
while (await reader.ReadAsync())
{
Console.WriteLine("SingerId : " + reader.GetFieldValue <string>("SingerId")
+ " AlbumId : " + reader.GetFieldValue <string>("AlbumId")
+ " AlbumTitle : " + reader.GetFieldValue <string>("AlbumTitle"));
}
}
// Read #2. Even if changes occur in-between the reads,
// the transaction ensures that Read #1 and Read #2
// return the same data.
using (var reader = await cmd.ExecuteReaderAsync())
{
while (await reader.ReadAsync())
{
albums.Add(new Album
{
AlbumId = reader.GetFieldValue <int>("AlbumId"),
SingerId = reader.GetFieldValue <int>("SingerId"),
AlbumTitle = reader.GetFieldValue <string>("AlbumTitle")
});
}
}
scope.Complete();
Console.WriteLine("Transaction complete.");
return(albums);
}
