private static async Task SetupAsync(EmulatorRunner emulatorRunner)
{
Console.WriteLine("");
Console.WriteLine("Starting emulator...");
emulatorRunner.StartEmulator().WaitWithUnwrappedExceptions();
Console.WriteLine("");
DatabaseName databaseName = DatabaseName.FromProjectInstanceDatabase(s_projectId, s_instanceId, s_databaseId);
await MaybeCreateInstanceOnEmulatorAsync(databaseName.ProjectId, databaseName.InstanceId);
await MaybeCreateDatabaseOnEmulatorAsync(databaseName);
}
internal static async Task RunSampleApp()
{
// Set the SPANNER_EMULATOR_HOST environment variable for this process. This
// ensures that the Entity Framework provider will connect to the emulator
// instead of to the real Google Cloud Spanner. Remove this line if you want
// to test the application against a real Spanner database.
Environment.SetEnvironmentVariable("SPANNER_EMULATOR_HOST", "localhost:9010");
var emulatorRunner = new EmulatorRunner();
try
{
// This starts an in-mem emulator and creates the sample database.
await SetupAsync(emulatorRunner);
// Create the connection string that will be used.
DatabaseName databaseName = DatabaseName.FromProjectInstanceDatabase(s_projectId, s_instanceId, s_databaseId);
var dataSource = $"Data Source={databaseName}";
var connectionString = new SpannerConnectionStringBuilder(dataSource)
{
EmulatorDetection = EmulatorDetection.EmulatorOrProduction,
}.ConnectionString;
Console.WriteLine($"Connecting to database {connectionString}");
// Create a DbContext that uses our sample Spanner database.
using var context = new SpannerTutorialContext(connectionString);
var singer = new Singer
{
SingerId = Guid.NewGuid(),
FirstName = "Bob",
LastName = "Allison",
};
context.Singers.Add(singer);
var album = new Album
{
AlbumId = Guid.NewGuid(),
Title = "Let's Go",
Singer = singer,
};
context.Albums.Add(album);
var track = new Track
{
Album = album,
TrackId = 1L,
Title = "Go, Go, Go",
};
context.Tracks.Add(track);
// This saves all the above changes in one transaction.
Console.WriteLine($"Writing Singer, Album and Track to the database");
var count = await context.SaveChangesAsync();
Console.WriteLine($"{count} records written to the database\n");
// Get a single entity. Note that the primary key of Track consists
// of both the parent AlbumId and the Id of the Track.
var foundTrack = await context.Tracks.FindAsync(album.AlbumId, 1L);
Console.WriteLine($"Found track {track.Title}");
// You can use LINQ to query the data that was written.
var singers = await context.Singers
.Where(s => s.FullName == "Bob Allison")
.ToListAsync();
Console.WriteLine($"Found {singers.Count} singer(s) with full name {singers.First().LastName}");
}
finally
{
Console.WriteLine("");
Console.WriteLine("Stopping emulator...");
emulatorRunner.StopEmulator().WaitWithUnwrappedExceptions();
Console.WriteLine("");
}
}