Add async streaming example

Author: ejsmith

README.md

@@ -375,9 +375,8 @@ The source generator provides compile-time errors for:
   - Ability to call `AddMediator` to entry assembly and have it register handlers in all assemblies
 - [ ] Clean architecture sample app
 - [ ] Modular monolith architecture sample app
-- [ ] Switch source generator package name back to Foundatio.Mediator (maybe Foundatio.Mediator.Abstractions)
 - [ ] Figure out issue with props / targets files not being included
-- [ ] See if we can support streaming with IAsyncEnumerable
+- [ ] Talk about streaming support
 - [ ] Talk about lifetime. Handlers aren't registered in DI by default and are singleton instances. Just add your handler or services to DI if you want a different behavior.
 - [ ] Add GeneratedCodeAttribute
 - [ ] Talk about for tuple returns / cascading messages, if a middleware short circuits the response, the value will be returned as the first tuple item and all others will be null or default.

samples/ConsoleSample/Handlers/Handlers.cs

@@ -1,3 +1,4 @@
+using System.Runtime.CompilerServices;
 using ConsoleSample.Messages;
 using Foundatio.Mediator;
 using Microsoft.Extensions.Logging;
@@ -95,3 +96,28 @@ public Result<Order> Handle(GetOrder query)
         return (Result.NoContent(), new OrderDeleted(command.OrderId, DateTime.UtcNow));
     }
 }
+
+// Streaming handler example
+public class StreamingHandler
+{
+    private readonly ILogger<StreamingHandler> _logger;
+
+    public StreamingHandler(ILogger<StreamingHandler> logger)
+    {
+        _logger = logger;
+    }
+
+    public async IAsyncEnumerable<int> HandleAsync(CounterStreamRequest request, [EnumeratorCancellation] CancellationToken cancellationToken)
+    {
+        for (int i = 0; i < 10; i++)
+        {
+            _logger.LogInformation("Streaming value: {Value}", i);
+
+            if (cancellationToken.IsCancellationRequested)
+                yield break;
+
+            await Task.Delay(1000, cancellationToken);
+            yield return i;
+        }
+    }
+}

samples/ConsoleSample/Messages/Messages.cs

@@ -10,12 +10,12 @@ public record GetGreeting(string Name);
 public record CreateOrder(
     [Required(ErrorMessage = "Customer ID is required")]
     [StringLength(50, MinimumLength = 3, ErrorMessage = "Customer ID must be between 3 and 50 characters")]
-    string CustomerId, 
-    
+    string CustomerId,
+
     [Required(ErrorMessage = "Amount is required")]
     [Range(0.01, 1000000, ErrorMessage = "Amount must be between $0.01 and $1,000,000")]
-    decimal Amount, 
-    
+    decimal Amount,
+
     [Required(ErrorMessage = "Description is required")]
     [StringLength(200, MinimumLength = 5, ErrorMessage = "Description must be between 5 and 200 characters")]
     string Description);
@@ -30,3 +30,6 @@ public record OrderDeleted(string OrderId, DateTime DeletedAt);
 
 // Order model
 public record Order(string Id, string CustomerId, decimal Amount, string Description, DateTime CreatedAt, DateTime? UpdatedAt = null);
+
+// Counter stream request
+public record CounterStreamRequest { }

samples/ConsoleSample/SampleRunner.cs

@@ -19,6 +19,7 @@ public async Task RunAllSamplesAsync()
 
         await RunSimpleExamples();
         await RunOrderCrudExamples();
+        await RunCounterStreamExample();
         await RunEventPublishingExamples();
 
         Console.WriteLine("\n🎉 All samples completed successfully!");
@@ -89,6 +90,28 @@ private async Task RunOrderCrudExamples()
         }
     }
 
+    private async Task RunCounterStreamExample()
+    {
+        Console.WriteLine("2️⃣ Counter Stream Example");
+        Console.WriteLine("==========================\n");
+
+        Console.WriteLine("🔢 Starting counter stream...");
+
+        CancellationTokenSource cts = new();
+        int count = 10;
+        await foreach (var item in _mediator.Invoke<IAsyncEnumerable<int>>(new CounterStreamRequest(), cts.Token))
+        {
+            count--;
+            if (count == 0)
+            {
+                cts.Cancel();
+            }
+            Console.WriteLine($"Counter: {item}");
+        }
+
+        Console.WriteLine("✅ Counter stream completed.\n");
+    }
+
     private async Task RunEventPublishingExamples()
     {
         Console.WriteLine("3️⃣ Event Publishing (Multiple Handlers)");