Merge pull request #3 from erikshafer/project_03_advanced_esdb

Project 03: Beginner++ ESDB

StudentEnrollment01.InMemory/Events/Event.cs

@@ -3,6 +3,5 @@ namespace StudentEnrollment01.InMemory.Events;
 public abstract class Event
 {
     public abstract Guid StreamId { get; }
-
     public DateTime CreatedAtUtc { get; set; }
 }

StudentEnrollment01.InMemory/Program.cs

@@ -19,6 +19,6 @@
 var student = inMemoryDb.GetStudent(id);
 
 Console.WriteLine(
-    "StudentId: {0} | FullName: {1} | Email: {2} | DOB: {3} | CreatedAtUtc: {4}", 
+    "StudentId: {0} | FullName: {1} | Email: {2} | DateOfBirth: {3} | CreatedAtUtc: {4}", 
     student!.Id, student.FullName, student.Email, student.DateOfBirth, student.CreatedAtUtc);
 Console.WriteLine();

StudentEnrollment01.InMemory/Student.cs

@@ -53,6 +53,6 @@ private void Apply(StudentEnrolled @event)
     private void Apply(StudentUnEnrolled @event)
     {
         if (EnrolledCourses.Contains(@event.CourseName))
-            EnrolledCourses.Add(@event.CourseName);
+            EnrolledCourses.Remove(@event.CourseName);
     }
 }

StudentEnrollment02.Esdb/Events/Event.cs

@@ -1,7 +1,7 @@
 namespace StudentEnrollment02.Esdb.Events;
 
-public abstract record Event
+public abstract class Event
 {
-    public string Id { get; init; } = default!;
+    public required string StudentId { get; set; }
     public DateTime CreatedAtUtc { get; set; }
 }

StudentEnrollment02.Esdb/Events/StudentCreated.cs

@@ -1,9 +1,8 @@
 namespace StudentEnrollment02.Esdb.Events;
 
-public record StudentCreated : Event
+public class StudentCreated : Event
 {
     public required string FullName { get; init; }
     public required string Email { get; init; }
     public required DateTime DateOfBirth { get; init; }
-    public DateTime CreatedAtUtc { get; init; }
 }

StudentEnrollment02.Esdb/Events/StudentEnrolled.cs

@@ -1,7 +1,6 @@
 namespace StudentEnrollment02.Esdb.Events;
 
-public record StudentEnrolled : Event
+public class StudentEnrolled : Event
 {
     public required string CourseName { get; init; }
-    public DateTime EnrolledAtUtc { get; init; }
 }

StudentEnrollment02.Esdb/Events/StudentUpdated.cs

@@ -0,0 +1,7 @@
+namespace StudentEnrollment02.Esdb.Events;
+
+public class StudentUpdated : Event
+{
+    public required string FullName { get; init; }
+    public required string Email { get; init; }
+}

StudentEnrollment02.Esdb/Events/StudentWithdrew.cs

@@ -0,0 +1,6 @@
+namespace StudentEnrollment02.Esdb.Events;
+
+public class StudentWithdrew : Event
+{
+    public required string CourseName { get; init; }
+}

StudentEnrollment02.Esdb/Program.cs

@@ -3,21 +3,14 @@
 using EventStore.Client;
 using StudentEnrollment02.Esdb.Events;
 
-// Register events to a singleton for ease-of-reference
-EventTypeMapper.Instance.ToName(typeof(StudentCreated));
-EventTypeMapper.Instance.ToName(typeof(StudentEnrolled));
-EventTypeMapper.Instance.ToName(typeof(StudentWithdrawn));
-EventTypeMapper.Instance.ToName(typeof(StudentEmailChanged));
-
-var id = Guid.Parse("a662d446-4920-415e-8c2a-0dd4a6c58908");
-var streamId = $"student-{id}";
+var streamId = Guid.Parse("a662d446-4920-415e-8c2a-0dd4a6c58908").ToString();
 
 var created = new EventData(
     Uuid.NewUuid(),
     "StudentCreated",
     JsonSerializer.SerializeToUtf8Bytes(new StudentCreated
     {
-        Id = streamId,
+        StudentId = streamId,
         FullName = "Erik Shafer",
         Email = "[email protected]",
         DateOfBirth = new DateTime(1987, 1, 1),
@@ -30,46 +23,47 @@
     "StudentEnrolled",
     JsonSerializer.SerializeToUtf8Bytes(new StudentEnrolled
     {
-        Id = streamId,
+        StudentId = streamId,
         CourseName = "From Zero to Hero: REST APis in .NET",
-        EnrolledAtUtc = DateTime.UtcNow
+        CreatedAtUtc = DateTime.UtcNow
     })
 );
 
 var emailChanged = new EventData(
     Uuid.NewUuid(),
     "StudentEmailChanged",
-    JsonSerializer.SerializeToUtf8Bytes(new StudentEmailChanged
+    JsonSerializer.SerializeToUtf8Bytes(new StudentUpdated
     {
-        Id = streamId,
+        StudentId = streamId,
+        FullName = "Erik Shafer",
         Email = "[email protected]",
-        ChangedAtUtc = DateTime.UtcNow
+        CreatedAtUtc = DateTime.UtcNow
     })
 );
 
-// Our EventStoreDB (ESDB)
 const string connectionString = "esdb://admin:changeit@localhost:2113?tls=false&tlsVerifyCert=false";
 var settings = EventStoreClientSettings.Create(connectionString);
 var client = new EventStoreClient(settings);
 
-// Append to ESDB
 await client.AppendToStreamAsync(
     streamId,
     StreamState.Any,
     new[] { created, enrolled, emailChanged },
     cancellationToken: default
 );
 
-// Read from ESDB
-var readStreamResult = client.ReadStreamAsync(
+var streamResult = client.ReadStreamAsync(
     Direction.Forwards,
     streamId,
     StreamPosition.Start,
     cancellationToken: default
 );
-var eventStream = await readStreamResult.ToListAsync();
 
-// Write out the events from the stream
+if (await streamResult.ReadState is ReadState.StreamNotFound)
+    return;
+
+var eventStream = await streamResult.ToListAsync();
+
 Console.WriteLine("Events from selected stream: ");
 foreach (var resolved in eventStream)
 {
@@ -80,28 +74,11 @@ await client.AppendToStreamAsync(
     Console.WriteLine("");
 }
 
-// Write out all the courses the student enrolled in
 var enrolledCourses = eventStream
     .Where(re => re.Event.EventType == "StudentEnrolled")
     .Select(re => JsonSerializer.Deserialize<StudentEnrolled>(re.Event.Data.ToArray()))
     .Select(se => se!.CourseName)
     .ToList();
 Console.WriteLine("Courses enrolled in: ");
 enrolledCourses.ForEach(ec => Console.WriteLine($"\t- {ec}"));
-Console.WriteLine("");
-
-// Write out using the mapper
-Console.WriteLine("Deserialized events:");
-foreach (var resolved in eventStream)
-{
-    var eventType = EventTypeMapper.Instance.ToType(resolved.Event.EventType);
-
-    if (eventType == null)
-        break;
-
-    var deserializedEvent = JsonSerializer.Deserialize(Encoding.UTF8.GetString(resolved.Event.Data.Span), eventType);
-
-    Console.WriteLine($"\t{deserializedEvent}");
-}
-
 Console.WriteLine("");

StudentEnrollment02.Esdb/Student.cs

@@ -18,27 +18,27 @@ public void Apply(Event @event)
             case StudentCreated created:
                 Apply(created);
                 break;
-            case StudentEmailChanged emailChanged:
+            case StudentUpdated emailChanged:
                 Apply(emailChanged);
                 break;
             case StudentEnrolled enrolled:
                 Apply(enrolled);
                 break;
-            case StudentWithdrawn withdrawn:
+            case StudentWithdrew withdrawn:
                 Apply(withdrawn);
                 break;
         }
     }
 
     private void Apply(StudentCreated @event)
     {
-        Id = @event.Id;
+        Id = @event.StudentId;
         FullName = @event.FullName;
         Email = @event.Email;
         CreatedAtUtc = @event.CreatedAtUtc;
     }
 
-    private void Apply(StudentEmailChanged @event)
+    private void Apply(StudentUpdated @event)
     {
         Email = @event.Email;
     }
@@ -49,9 +49,9 @@ private void Apply(StudentEnrolled @event)
             EnrolledCourses.Add(@event.CourseName);
     }
 
-    private void Apply(StudentWithdrawn @event)
+    private void Apply(StudentWithdrew @event)
     {
         if (EnrolledCourses.Contains(@event.CourseName))
-            EnrolledCourses.Add(@event.CourseName);
+            EnrolledCourses.Remove(@event.CourseName);
     }
 }

StudentEnrollment03.Esdb/Events/Event.cs

@@ -0,0 +1,6 @@
+namespace StudentEnrollment03.Esdb.Events;
+
+public abstract record Event
+{
+    public string Id { get; init; } = default!;
+}

StudentEnrollment03.Esdb/Events/EventTypeMapper.cs

@@ -0,0 +1,35 @@
+using System.Collections.Concurrent;
+
+namespace StudentEnrollment03.Esdb.Events;
+
+public class EventTypeMapper
+{
+    public static readonly EventTypeMapper Instance = new();
+
+    private readonly ConcurrentDictionary<string, Type?> _typeMap = new();
+    private readonly ConcurrentDictionary<Type, string> _typeNameMap = new();
+
+    public string ToName<TEventType>() => ToName(typeof(TEventType));
+
+    public string ToName(Type eventType) => _typeNameMap.GetOrAdd(eventType, _ =>
+    {
+        var eventTypeName = eventType.FullName!;
+        _typeMap.TryAdd(eventTypeName, eventType);
+        return eventTypeName;
+    });
+
+    public Type? ToType(string eventTypeName) => _typeMap.GetOrAdd(eventTypeName, _ =>
+    {
+        var type = AppDomain.CurrentDomain
+            .GetAssemblies()
+            .SelectMany(a => a.GetTypes().Where(x => x.FullName == eventTypeName || x.Name == eventTypeName))
+            .FirstOrDefault();
+
+        if (type == null)
+            return null;
+
+        _typeNameMap.TryAdd(type, eventTypeName);
+
+        return type;
+    });
+}

StudentEnrollment03.Esdb/Events/StudentCreated.cs

@@ -0,0 +1,9 @@
+namespace StudentEnrollment03.Esdb.Events;
+
+public record StudentCreated : Event
+{
+    public required string FullName { get; init; }
+    public required string Email { get; init; }
+    public required DateTime DateOfBirth { get; init; }
+    public DateTime CreatedAtUtc { get; init; }
+}

StudentEnrollment02.Esdb/Events/StudentEmailChanged.cs → StudentEnrollment03.Esdb/Events/StudentEmailChanged.cs

@@ -1,4 +1,4 @@
-namespace StudentEnrollment02.Esdb.Events;
+namespace StudentEnrollment03.Esdb.Events;
 
 public record StudentEmailChanged : Event
 {

StudentEnrollment03.Esdb/Events/StudentEnrolled.cs

@@ -0,0 +1,8 @@
+namespace StudentEnrollment03.Esdb.Events;
+
+public record StudentEnrolled : Event
+{
+    public required string CourseName { get; init; }
+    public required string InstructorName { get; init; }
+    public DateTime EnrolledAtUtc { get; init; }
+}

StudentEnrollment02.Esdb/Events/StudentWithdrawn.cs → StudentEnrollment03.Esdb/Events/StudentWithdrew.cs

@@ -1,6 +1,6 @@
-namespace StudentEnrollment02.Esdb.Events;
+namespace StudentEnrollment03.Esdb.Events;
 
-public record StudentWithdrawn : Event
+public record StudentWithdrew : Event
 {
     public required string CourseName { get; init; }
     public DateTime WithdrawnAtUtc { get; init; }