public void CreateUser(UserCreationSpec userToCreate) { if (userToCreate == null) throw new ArgumentNullException("userToCreate"); userToCreate.Validate(); /* * Typical usage of DbContextScope for a read-write business transaction. * It's as simple as it looks. */ using (var dbContextScope = _dbContextScopeFactory.Create()) { //-- Build domain model var user = new User() { Id = userToCreate.Id, Name = userToCreate.Name, Email = userToCreate.Email, WelcomeEmailSent = false, CreatedOn = DateTime.UtcNow }; //-- Persist _userRepository.Add(user); dbContextScope.SaveChanges(); } }
static void Main(string[] args) { //-- Poor-man DI - build our dependencies by hand for this demo var dbContextScopeFactory = new DbContextScopeFactory(); var ambientDbContextLocator = new AmbientDbContextLocator(); var userRepository = new UserRepository(ambientDbContextLocator); var userCreationService = new UserCreationService(dbContextScopeFactory, userRepository); var userQueryService = new UserQueryService(dbContextScopeFactory, userRepository); var userEmailService = new UserEmailService(dbContextScopeFactory); var userCreditScoreService = new UserCreditScoreService(dbContextScopeFactory); try { Console.WriteLine("This demo application will create a database named DbContextScopeDemo in the default SQL Server instance on localhost. Edit the connection string in UserManagementDbContext if you'd like to create it somewhere else."); Console.WriteLine("Press enter to start..."); Console.ReadLine(); //-- Demo of typical usage for read and writes Console.WriteLine("Creating a user called Mary..."); var marysSpec = new UserCreationSpec("Mary", "*****@*****.**"); userCreationService.CreateUser(marysSpec); Console.WriteLine("Done.\n"); Console.WriteLine("Trying to retrieve our newly created user from the data store..."); var mary = userQueryService.GetUser(marysSpec.Id); Console.WriteLine("OK. Persisted user: {0}", mary); Console.WriteLine("Press enter to continue..."); Console.ReadLine(); //-- Demo of nested DbContextScopes Console.WriteLine("Creating 2 new users called John and Jeanne in an atomic transaction..."); var johnSpec = new UserCreationSpec("John", "*****@*****.**"); var jeanneSpec = new UserCreationSpec("Jeanne", "*****@*****.**"); userCreationService.CreateListOfUsers(johnSpec, jeanneSpec); Console.WriteLine("Done.\n"); Console.WriteLine("Trying to retrieve our newly created users from the data store..."); var createdUsers = userQueryService.GetUsers(johnSpec.Id, jeanneSpec.Id); Console.WriteLine("OK. Found {0} persisted users.", createdUsers.Count()); Console.WriteLine("Press enter to continue..."); Console.ReadLine(); //-- Demo of nested DbContextScopes in the face of an exception. // If any of the provided users failed to get persisted, none should get persisted. Console.WriteLine("Creating 2 new users called Julie and Marc in an atomic transaction. Will make the persistence of the second user fail intentionally in order to test the atomicity of the transaction..."); var julieSpec = new UserCreationSpec("Julie", "*****@*****.**"); var marcSpec = new UserCreationSpec("Marc", "*****@*****.**"); try { userCreationService.CreateListOfUsersWithIntentionalFailure(julieSpec, marcSpec); Console.WriteLine("Done.\n"); } catch (Exception e) { Console.WriteLine(e.Message); Console.WriteLine(); } Console.WriteLine("Trying to retrieve our newly created users from the data store..."); var maybeCreatedUsers = userQueryService.GetUsers(julieSpec.Id, marcSpec.Id); Console.WriteLine("Found {0} persisted users. If this number is 0, we're all good. If this number is not 0, we have a big problem.", maybeCreatedUsers.Count()); Console.WriteLine("Press enter to continue..."); Console.ReadLine(); //-- Demo of explicit database transaction. Console.WriteLine("Trying to retrieve user John within a READ UNCOMMITTED database transaction..."); // You'll want to use SQL Profiler or Entity Framework Profiler to verify that the correct transaction isolation // level is being used. var userMaybeUncommitted = userQueryService.GetUserUncommitted(johnSpec.Id); Console.WriteLine("OK. User found: {0}", userMaybeUncommitted); Console.WriteLine("Press enter to continue..."); Console.ReadLine(); //-- Demo of disabling the DbContextScope nesting behaviour in order to force the persistence of changes made to entities // This is a pretty advanced feature that you can safely ignore until you actually need it. Console.WriteLine("Will simulate sending a Welcome email to John..."); using (var parentScope = dbContextScopeFactory.Create()) { var parentDbContext = parentScope.DbContexts.Get<UserManagementDbContext>(); // Load John in the parent DbContext var john = parentDbContext.Users.Find(johnSpec.Id); Console.WriteLine("Before calling SendWelcomeEmail(), john.WelcomeEmailSent = " + john.WelcomeEmailSent); // Now call our SendWelcomeEmail() business logic service method, which will // update John in a non-nested child context userEmailService.SendWelcomeEmail(johnSpec.Id); // Verify that we can see the modifications made to John by the SendWelcomeEmail() method Console.WriteLine("After calling SendWelcomeEmail(), john.WelcomeEmailSent = " + john.WelcomeEmailSent); // Note that even though we're not calling SaveChanges() in the parent scope here, the changes // made to John by SendWelcomeEmail() will remain persisted in the database as SendWelcomeEmail() // forced the creation of a new DbContextScope. } Console.WriteLine("Press enter to continue..."); Console.ReadLine(); //-- Demonstration of DbContextScope and parallel programming Console.WriteLine("Calculating and storing the credit score of all users in the database in parallel..."); userCreditScoreService.UpdateCreditScoreForAllUsers(); Console.WriteLine("Done."); } catch (Exception e) { Console.WriteLine(e); } Console.WriteLine(); Console.WriteLine("The end."); Console.WriteLine("Press enter to exit..."); Console.ReadLine(); }