Use resource filter instead of middleware

samples/transactional-session/aspnetcore-webapi/SqlPersistenceTS_6/WebApplication/MessageSessionFilter.cs

@@ -0,0 +1,27 @@
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.Filters;
+using Microsoft.Extensions.DependencyInjection;
+using NServiceBus.TransactionalSession;
+
+public sealed class MessageSessionFilter : IAsyncResourceFilter
+{
+    public async Task OnResourceExecutionAsync(ResourceExecutingContext context, ResourceExecutionDelegate next)
+    {
+        context.HttpContext.Items.Add(nameof(MessageSessionFilter), null);
+
+        var session = context.HttpContext.RequestServices.GetRequiredService<ITransactionalSession>();
+        await session.Open(new SqlPersistenceOpenSessionOptions());
+
+        await next();
+
+        await session.Commit();
+    }
+}
+
+public sealed class RequiresTransactionalSession : ServiceFilterAttribute
+{
+    public RequiresTransactionalSession() : base(typeof(MessageSessionFilter))
+    {
+    }
+}

samples/transactional-session/aspnetcore-webapi/SqlPersistenceTS_6/WebApplication/Program.cs

@@ -1,6 +1,7 @@
 using Microsoft.Data.SqlClient;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Http;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
@@ -10,7 +11,7 @@
 using NServiceBus.TransactionalSession;
 
 public class Program
-{    
+{
     // for SqlExpress use Data Source=.\SqlExpress;Initial Catalog=nservicebus;Integrated Security=True;Encrypt=false
     const string ConnectionString = @"Server=localhost,1433;Initial Catalog=nservicebus;User Id=SA;Password=yourStrong(!)Password;Encrypt=false";
 
@@ -48,33 +49,56 @@ public static void Main()
             #region txsession-ef-configuration
             .ConfigureServices(c =>
             {
-                // Configure Entity Framework to attach to the synchronized storage session
+                // Configure Entity Framework to attach to the synchronized storage session when required
                 c.AddScoped(b =>
                 {
-                    var session = b.GetRequiredService<ISqlStorageSession>();
-                    var context = new MyDataContext(new DbContextOptionsBuilder<MyDataContext>()
-                        .UseSqlServer(session.Connection)
-                        .Options);
+                    var requiresSessionIntegration = true;
+                    var contextAccessor = b.GetRequiredService<IHttpContextAccessor>();
+                    if (contextAccessor.HttpContext != null && !contextAccessor.HttpContext.Items.TryGetValue(nameof(MessageSessionFilter), out _))
+                    {
+                        requiresSessionIntegration = false;
+                    }
 
-                    //Use the same underlying ADO.NET transaction
-                    context.Database.UseTransaction(session.Transaction);
+                    if (requiresSessionIntegration)
+                    {
+                        var session = b.GetRequiredService<ISqlStorageSession>();
+                        var context = new MyDataContext(new DbContextOptionsBuilder<MyDataContext>()
+                            .UseSqlServer(session.Connection)
+                            .Options);
 
-                    //Ensure context is flushed before the transaction is committed
-                    session.OnSaveChanges((s) => context.SaveChangesAsync());
+                        //Use the same underlying ADO.NET transaction
+                        context.Database.UseTransaction(session.Transaction);
+
+                        //Ensure context is flushed before the transaction is committed
+                        session.OnSaveChanges((s) => context.SaveChangesAsync());
+
+                        return context;
+                    }
+                    else
+                    {
+                        var context = new MyDataContext(new DbContextOptionsBuilder<MyDataContext>()
+                            .UseSqlServer(ConnectionString)
+                            .Options);
+                        return context;
+                    }
 
-                    return context;
                 });
             })
             #endregion
 
             .ConfigureWebHostDefaults(c =>
             {
-                c.ConfigureServices(s => s.AddControllers());
-                c.Configure(app =>
+                c.ConfigureServices(s =>
                 {
+                    s.AddControllers();
+
                     #region txsession-web-configuration
-                    app.UseMiddleware<MessageSessionMiddleware>();
+                    s.AddScoped<MessageSessionFilter>();
+                    s.AddHttpContextAccessor();
                     #endregion
+                });
+                c.Configure(app =>
+                {
                     app.UseRouting();
                     app.UseEndpoints(r => r.MapControllers());
                 });
@@ -83,4 +107,4 @@ public static void Main()
 
         host.Run();
     }
-}
+}

samples/transactional-session/aspnetcore-webapi/SqlPersistenceTS_6/WebApplication/SendMessageController.cs

@@ -1,6 +1,9 @@
 using System;
+using System.Collections.Generic;
+using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore;
 using NServiceBus.TransactionalSession;
 
 [ApiController]
@@ -18,6 +21,7 @@ public SendMessageController(ITransactionalSession messageSession, MyDataContext
 
     #region txsession-controller
     [HttpGet]
+    [RequiresTransactionalSession]
     public async Task<string> Get()
     {
         var id = Guid.NewGuid().ToString();
@@ -31,4 +35,12 @@ await messageSession.SendLocal(message)
         return $"Message with entity ID '{id}' sent to endpoint";
     }
     #endregion
-}
+
+    #region txsession-controller-query
+    [HttpGet("/all")]
+    public async Task<List<MyEntity>> GetAll()
+    {
+        return await dataContext.MyEntities.ToListAsync();
+    }
+    #endregion
+}