Failing multistream testcase

Would expect Identities, many-to-one, to project the view i into the 2nd Apply method.

src/EventSourcingTests/Projections/MultiStreamProjections/TestClasses.cs

@@ -135,4 +135,32 @@ public class UserGroupsAssignment
  public List<Guid> Groups { get; set; } = new();
 }
 
-#endregion
+#endregion
+
+
+// Notification example
+public class Notification
+{
+ public string Id { get; set; }
+ public string Title { get; set; }
+ public string Content { get; set; }
+
+ public Notification(string id, string title, string content)
+ {
+ Id = id;
+ Title = title;
+ Content = content;
+ }
+}
+
+public class UserNotification
+{
+ public string Id { get; set; }
+ public string UserId { get; set; }
+ public string NotificationId { get; set; }
+ public bool isOpened { get; set; }
+}
+
+// Notification events
+public record SendNotificationToUsers(Notification Notification, List<string> UserIds);
+public record UserOpenedNotification(string NotificationId, string UserId);

src/EventSourcingTests/Projections/MultiStreamProjections/simple_multi_stream_projection_wih_one_to_many_notification_many_first.cs

@@ -0,0 +1,81 @@
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using Marten.Events.Projections;
+using Marten.Testing.Harness;
+using Shouldly;
+using Xunit;
+
+namespace EventSourcingTests.Projections.MultiStreamProjections.Samples
+{
+ #region sample_view-projection-simple-with-one-to-many
+
+ public class UserNotificationProjection: MultiStreamProjection<UserNotification, string>
+ {
+ public UserNotificationProjection()
+ {
+ Identity<UserOpenedNotification>(x => x.UserId);
+ Identities<SendNotificationToUsers>(x => x.UserIds);
+ }
+
+ public void Apply(UserOpenedNotification @event, UserNotification view)
+ {
+ view.isOpened = true;
+ }
+
+ public void Apply(SendNotificationToUsers @event, UserNotification view)
+ {
+ Assert.NotNull(view.Id); //! Fails
+ view.Id = $"{view.Id}:{@event.Notification.Id}"; // I want the userNotification id to be "userId:notificationId", but since the matched userId is not available here, I can't do that.
+ view.NotificationId = @event.Notification.Id;
+ }
+ }
+
+ #endregion
+}
+
+namespace EventSourcingTests.Projections.MultiStreamProjections
+{
+
+
+ public class simple_multi_stream_projection_with_one_to_many_notification_many_first: OneOffConfigurationsContext
+ {
+ [Fact]
+ public async Task multi_stream_projections_with_only_group_assign_should_work()
+ {
+ // Create a notification and send it to John and Anna
+ var notification = new Notification(Guid.NewGuid().ToString(), "Notification title", "Example content");
+
+ var johnUserId = Guid.NewGuid().ToString(); // UserId of John
+ var annaUserId = Guid.NewGuid().ToString(); // UserId of Anna
+
+ var sendNotificationToUsers = new SendNotificationToUsers(notification, new List<string> { johnUserId, annaUserId });
+ theSession.Events.Append(sendNotificationToUsers.Notification.Id, sendNotificationToUsers);
+
+ await theSession.SaveChangesAsync(); //! FAILS because of inner assert
+
+ // Open the notification for John
+ var userOpenedNotification = new UserOpenedNotification(notification.Id, johnUserId);
+ theSession.Events.Append(userOpenedNotification.UserId, userOpenedNotification);
+
+ await theSession.SaveChangesAsync();
+
+ // Check if the notification is opened for John
+ var userNotification = await theSession.LoadAsync<UserNotification>($"{johnUserId}:{notification.Id}");
+ userNotification.isOpened.ShouldBeTrue();
+
+ // Check if the notification is not opened for Anna
+ userNotification = await theSession.LoadAsync<UserNotification>($"{annaUserId}:{notification.Id}");
+ userNotification.isOpened.ShouldBeFalse();
+ }
+
+ public simple_multi_stream_projection_with_one_to_many_notification_many_first()
+ {
+ StoreOptions(_ =>
+ {
+ _.Events.StreamIdentity = Marten.Events.StreamIdentity.AsString;
+ _.Projections.Add<EventSourcingTests.Projections.MultiStreamProjections.Samples.UserNotificationProjection>(ProjectionLifecycle.Inline);
+ });
+ }
+ }
+}