197_Saga_Storage

Saga Storage

Wolverine can use registered EF Core DbContext types for saga persistence as long as the EF Core transactional support is added to the application. There’s absolutely nothing you need to do to enable this except for having a mapping for whatever Saga type you need to persist in a registered DbContext type. As long as your DbContext with a mapping for a particular Saga type is registered in the IoC container for your application and Wolverine’s EF Core transactional support is active, Wolverine will be able to find and use the correct DbContext type for your Saga at runtime.

You do not need to use the WolverineOptions.AddSagaType<T>() option with EF Core saga, that option is strictly for the lightweight saga storage with SQL Server or PostgreSQL.

To make that concrete, let’s say you’ve got a simplistic Order saga type like this:

public enum OrderStatus
{
    Pending = 0,
    CreditReserved = 1,
    CreditLimitExceeded = 2,
    Approved = 3,
    Rejected = 4
}
 
public class Order : Saga
{
    public string? Id { get; set; }
    public OrderStatus OrderStatus { get; set; } = OrderStatus.Pending;
 
    public object[] Start(
        OrderPlaced orderPlaced,
        ILogger logger
    )
    {
        Id = orderPlaced.OrderId;
        logger.LogInformation("Order {OrderId} placed", Id);
        OrderStatus = OrderStatus.Pending;
        return
        [
            new ReserveCredit(
                orderPlaced.OrderId,
                orderPlaced.CustomerId,
                orderPlaced.Amount
            )
        ];
    }
 
    public object[] Handle(
        CreditReserved creditReserved,
        ILogger logger
    )
    {
        OrderStatus = OrderStatus.CreditReserved;
        logger.LogInformation("Credit reserver for Order {OrderId}", Id);
        return [new ApproveOrder(creditReserved.OrderId, creditReserved.CustomerId)];
    }
 
    public void Handle(
        OrderApproved orderApproved,
        ILogger logger
    )
    {
        OrderStatus = OrderStatus.Approved;
        logger.LogInformation("Order {OrderId} approved", Id);
    }
 
    public object[] Handle(
        CreditLimitExceeded creditLimitExceeded,
        ILogger logger
    )
    {
        OrderStatus = OrderStatus.CreditLimitExceeded;
        return [new RejectOrder(creditLimitExceeded.OrderId)];
    }
 
    public void Handle(
        OrderRejected orderRejected,
        ILogger logger
    )
    {
        OrderStatus = OrderStatus.Rejected;
        logger.LogInformation("Order {OrderId} rejected", Id);
        MarkCompleted();
    }
}

snippet source | anchor

And a matching OrdersDbContext that can persist that type like so:

public class OrdersDbContext : DbContext
{
    protected OrdersDbContext()
    {
    }
 
    public OrdersDbContext(DbContextOptions options) : base(options)
    {
    }
    
    public DbSet<Order> Orders { get; set; }
 
    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        // Your normal EF Core mapping
        modelBuilder.Entity<Order>(map =>
        {
            map.ToTable("orders", "sample");
            map.HasKey(x => x.Id);
            map.Property(x => x.OrderStatus)
                .HasConversion(v => v.ToString(), v => Enum.Parse<OrderStatus>(v));
        });
    }
}

snippet source | anchor

There’s no other registration to do other than adding the OrdersDbContext to your IoC container and enabling the Wolverine EF Core middleware as shown in the getting started with EF Core section.

When to Use EF Core vs Lightweight Storage?

As to the question, when should you opt for lightweight storage where Wolverine just sticks serialized JSON into a single field for a saga versus using fullblown EF Core mapping? If you have any need to also persist other data with a DbContext service while executing any of the Saga steps, use EF Core mapping with that same DbContext type so that Wolverine can easily manage the changes in one single transaction. If you prefer having a flat table, maybe just because it’ll be easier to monitor through normal database tooling, use EF Core. If you just want to go fast and don’t want to mess with ORM mapping, then use the lightweight storage with Wolverine.

Do note that using AddSagaType<T>() for a Saga type will win out over any EF Core mappings and Wolverine will try to use the lightweight storage in that case.

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url: /guide/durability/sagas.md