Transactional Middleware

Support for using Wolverine transactional middleware requires an explicit registration on WolverineOptions shown below (it's an extension method):

builder.Host.UseWolverine(opts =>
{
    // Setting up Sql Server-backed message storage
    // This requires a reference to Wolverine.SqlServer
    opts.PersistMessagesWithSqlServer(connectionString, "wolverine");

    // Set up Entity Framework Core as the support
    // for Wolverine's transactional middleware
    opts.UseEntityFrameworkCoreTransactions();

    // Enrolling all local queues into the
    // durable inbox/outbox processing
    opts.Policies.UseDurableLocalQueues();
});

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TIP

When using the opt in Handlers.AutoApplyTransactions() option, Wolverine (really Lamar) can detect that your handler method uses a DbContext if it's a method argument, a dependency of any service injected as a method argument, or a dependency of any service injected as a constructor argument of the handler class.

That will enroll EF Core as both a strategy for stateful saga support and for transactional middleware. With this option added, Wolverine will wrap transactional middleware around any message handler that has a dependency on any type of DbContext like this one:

[Transactional]
public static ItemCreated Handle(
    // This would be the message
    CreateItemCommand command,

    // Any other arguments are assumed
    // to be service dependencies
    ItemsDbContext db)
{
    // Create a new Item entity
    var item = new Item
    {
        Name = command.Name
    };

    // Add the item to the current
    // DbContext unit of work
    db.Items.Add(item);

    // This event being returned
    // by the handler will be automatically sent
    // out as a "cascading" message
    return new ItemCreated
    {
        Id = item.Id
    };
}

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When using the transactional middleware around a message handler, the DbContext is used to persist the outgoing messages as part of Wolverine's outbox support.

Auto Apply Transactional Middleware

You can opt into automatically applying the transactional middleware to any handler that depends on a DbContext type with the AutoApplyTransactions() option as shown below:

var builder = Host.CreateApplicationBuilder();
builder.UseWolverine(opts =>
{
    var connectionString = builder.Configuration.GetConnectionString("database");

    opts.Services.AddDbContextWithWolverineIntegration<SampleDbContext>(x =>
    {
        x.UseSqlServer(connectionString);
    });

    // Add the auto transaction middleware attachment policy
    opts.Policies.AutoApplyTransactions();
});

using var host = builder.Build();
await host.StartAsync();

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With this option, you will no longer need to decorate handler methods with the [Transactional] attribute.