Added README for versioning samples

oskardudycz · Dec 8, 2021 · bcdbeaa · bcdbeaa
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diff --git a/README.md b/README.md
@@ -25,10 +25,11 @@ Tutorial, practical samples and other resources about Event Sourcing in .NET Cor
     - [6.2 Simple EventSourcing with EventStoreDB](#62-simple-eventsourcing-with-eventstoredb)
     - [6.3 ECommerce with EventStoreDB](#63-ecommerce-with-eventstoredb)
     - [6.5 Warehouse](#65-warehouse)
-    - [6.6 Event Pipelines](#66-event-pipelines)
-    - [6.7 Meetings Management with Marten](#67-meetings-management-with-marten)
-    - [6.8 Cinema Tickets Reservations with Marten](#68-cinema-tickets-reservations-with-marten)
-    - [6.9 SmartHome IoT with Marten](#69-smarthome-iot-with-marten)
+    - [6.6 Event Versioning](#66-event-versioning)
+    - [6.7 Event Pipelines](#67-event-pipelines)
+    - [6.8 Meetings Management with Marten](#68-meetings-management-with-marten)
+    - [6.9 Cinema Tickets Reservations with Marten](#69-cinema-tickets-reservations-with-marten)
+    - [6.10 SmartHome IoT with Marten](#610-smarthome-iot-with-marten)
   - [7. Self-paced training Kit](#7-self-paced-training-kit)
   - [8. Articles](#8-articles)
   - [9. Event Store - Marten](#9-event-store---marten)
@@ -453,7 +454,21 @@ Samples are using CQRS architecture. They're sliced based on the business module
 - No Event Sourcing! Using Entity Framework to show that CQRS is not bounded to Event Sourcing or any type of storage,
 - No Aggregates! CQRS do not need DDD. Business logic can be handled in handlers.
 
-### 6.6 [Event Pipelines](./Sample/EventPipelines)
+### 6.6 [Event Versioning](./Sample/EventVersioning)
+Shows how to handle basic event schema versioning scenarios using event and stream transformations (e.g. upcasting):
+- [Simple mapping](./Sample/EventsVersioning/#simple-mapping)
+  - [New not required property](./Sample/EventsVersioning/#new-not-required-property)
+  - [New required property](./Sample/EventsVersioning/#new-required-property)
+  - [Renamed property](./Sample/EventsVersioning/#renamed-property)
+- [Upcasting](./Sample/EventsVersioning/#upcasting)
+  - [Changed Structure](./Sample/EventsVersioning/#changed-structure)
+  - [New required property](./Sample/EventsVersioning/#new-required-property-1)
+- [Downcasters](./Sample/EventsVersioning/#downcasters)
+- [Events Transformations](./Sample/EventsVersioning/#events-transformations)
+- [Stream Transformation](./Sample/EventsVersioning/#stream-transformation)
+- [Summary](./Sample/EventsVersioning/#summary)
+
+### 6.7 [Event Pipelines](./Sample/EventPipelines)
 Shows how to compose event handlers in the processing pipelines to:
 - filter events,
 - transform them,
@@ -464,20 +479,20 @@ Shows how to compose event handlers in the processing pipelines to:
 - can be used with Dependency Injection, but also without through builder,
 - integrates with MediatR if you want to.
 
-### 6.7 [Meetings Management with Marten](./Sample/MeetingsManagement/)
+### 6.8 [Meetings Management with Marten](./Sample/MeetingsManagement/)
 - typical Event Sourcing and CQRS flow,
 - DDD using Aggregates,
 - microservices example,
 - stores events to Marten,
 - Kafka as a messaging platform to integrate microservices,
 - read models handled in separate microservice and stored to other database (ElasticSearch)
 
-### 6.8 [Cinema Tickets Reservations with Marten](./Sample/Tickets/)
+### 6.9 [Cinema Tickets Reservations with Marten](./Sample/Tickets/)
 - typical Event Sourcing and CQRS flow,
 - DDD using Aggregates,
 - stores events to Marten.
 
-### 6.9 [SmartHome IoT with Marten](./Sample/AsyncProjections/)
+### 6.10 [SmartHome IoT with Marten](./Sample/AsyncProjections/)
 - typical Event Sourcing and CQRS flow,
 - DDD using Aggregates,
 - stores events to Marten,

diff --git a/Sample/EventPipelines/README.md b/Sample/EventPipelines/README.md
@@ -1,4 +1,4 @@
-# [Event Pipelines](./EventPipelines)
+# Event Pipelines
 
 Shows how to compose event handlers in the processing pipelines to:
 - filter events,

diff --git a/Sample/EventStoreDB/Simple/README.md b/Sample/EventStoreDB/Simple/README.md
@@ -1,6 +1,6 @@
 # Simple, practical EventSourcing with EventStoreDB and EntityFramework
 
-The PR is adding a new sample that contains the simple Event Sourcing setup with EventStoreDB. For the Read Model, Postgres and Entity Framework are used.
+The is the simple Event Sourcing setup with EventStoreDB. For the Read Model, Postgres and Entity Framework are used.
 
 You can watch the webinar on YouTube where I'm explaining the details of the implementation:
 

diff --git a/Sample/EventsVersioning/EventsVersioning.Tests/Downcasters/ChangedStructure.cs b/Sample/EventsVersioning/EventsVersioning.Tests/Downcasters/ChangedStructure.cs
@@ -18,27 +18,27 @@ public record ShoppingCartInitialized(
         Client Client
     );
 
-    public static V1.ShoppingCartInitialized Downcast(
-        ShoppingCartInitialized newEvent
-    )
-    {
-        return new V1.ShoppingCartInitialized(
-            newEvent.ShoppingCartId,
-            newEvent.Client.Id
-        );
-    }
+public static V1.ShoppingCartInitialized Downcast(
+    ShoppingCartInitialized newEvent
+)
+{
+    return new V1.ShoppingCartInitialized(
+        newEvent.ShoppingCartId,
+        newEvent.Client.Id
+    );
+}
 
-    public static V1.ShoppingCartInitialized Downcast(
-        string newEventJson
-    )
-    {
-        var newEvent = JsonDocument.Parse(newEventJson).RootElement;
+public static V1.ShoppingCartInitialized Downcast(
+    string newEventJson
+)
+{
+    var newEvent = JsonDocument.Parse(newEventJson).RootElement;
 
-        return new V1.ShoppingCartInitialized(
-            newEvent.GetProperty("ShoppingCartId").GetGuid(),
-            newEvent.GetProperty("Client").GetProperty("Id").GetGuid()
-        );
-    }
+    return new V1.ShoppingCartInitialized(
+        newEvent.GetProperty("ShoppingCartId").GetGuid(),
+        newEvent.GetProperty("Client").GetProperty("Id").GetGuid()
+    );
+}
 
     [Fact]
     public void UpcastObjects_Should_BeForwardCompatible()
@@ -74,4 +74,4 @@ public void UpcastJson_Should_BeForwardCompatible()
         @event.ShoppingCartId.Should().Be(newEvent.ShoppingCartId);
         @event.ClientId.Should().Be(newEvent.Client.Id);
     }
-}
+}
diff --git a/.../EventsVersioning.Tests/Transformations/MultipleTransformationsWithDifferentEventTypes.cs b/.../EventsVersioning.Tests/Transformations/MultipleTransformationsWithDifferentEventTypes.cs
@@ -86,7 +86,8 @@ public EventTransformations Register<TEvent>(string eventTypeName, Func<JsonDocu
             return this;
         }
 
-        public EventTransformations Register<TOldEvent, TEvent>(string eventTypeName, Func<TOldEvent, TEvent> transformEvent)
+        public EventTransformations Register<TOldEvent, TEvent>(string eventTypeName,
+            Func<TOldEvent, TEvent> transformEvent)
             where TOldEvent : notnull
             where TEvent : notnull
         {
@@ -100,7 +101,7 @@ public EventTransformations Register<TEvent>(string eventTypeName, Func<JsonDocu
 
     public class EventTypeMapping
     {
-        private readonly Dictionary<string, Type> mappings = new ();
+        private readonly Dictionary<string, Type> mappings = new();
 
         public EventTypeMapping Register<TEvent>(params string[] typeNames)
         {
@@ -130,7 +131,8 @@ public EventSerializer(EventTypeMapping mapping, EventTransformations transforma
 
         public object? Deserialize(string eventTypeName, string json) =>
             transformations.TryTransform(eventTypeName, json, out var transformed)
-                ? transformed : JsonSerializer.Deserialize(json, mapping.Map(eventTypeName));
+                ? transformed
+                : JsonSerializer.Deserialize(json, mapping.Map(eventTypeName));
     }
 
     [Fact]
@@ -160,15 +162,15 @@ public void UpcastObjects_Should_BeForwardCompatible()
         );
         var eventV2 = new ShoppingCartInitialized(
             Guid.NewGuid(),
-            new Client(Guid.NewGuid(), "Oscar the Grouch" )
+            new Client(Guid.NewGuid(), "Oscar the Grouch")
         );
         var eventV3 = new ShoppingCartInitializedWithStatus(
             Guid.NewGuid(),
             new Client(Guid.NewGuid(), "Big Bird"),
             ShoppingCartStatus.Pending
         );
 
-        var events = new []
+        var events = new[]
         {
             new { EventType = eventTypeV1Name, EventData = JsonSerializer.Serialize(eventV1) },
             new { EventType = eventTypeV2Name, EventData = JsonSerializer.Serialize(eventV2) },
@@ -198,4 +200,4 @@ public void UpcastObjects_Should_BeForwardCompatible()
         deserializedEvents[2].Client.Should().Be(eventV3.Client);
         deserializedEvents[2].Status.Should().Be(eventV3.Status);
     }
-}
+}
diff --git a/Sample/EventsVersioning/EventsVersioning.Tests/Transformations/StreamTransformations.cs b/Sample/EventsVersioning/EventsVersioning.Tests/Transformations/StreamTransformations.cs
@@ -289,4 +289,4 @@ public void UpcastObjects_Should_BeForwardCompatible()
         deserializedEvents[2].As<V1.ShoppingCartConfirmed>()
             .ShoppingCartId.Should().Be(shoppingCardId);
     }
-}
+}
diff --git a/Sample/EventsVersioning/EventsVersioning.Tests/Upcasters/ChangedStructure.cs b/Sample/EventsVersioning/EventsVersioning.Tests/Upcasters/ChangedStructure.cs
@@ -73,4 +73,4 @@ public void UpcastJson_Should_BeForwardCompatible()
         @event.Client.Id.Should().Be(oldEvent.ClientId);
         @event.Client.Name.Should().Be("Unknown");
     }
-}
+}
diff --git a/Sample/EventsVersioning/EventsVersioning.Tests/Upcasters/NewRequiredPropertyFromMetadata.cs b/Sample/EventsVersioning/EventsVersioning.Tests/Upcasters/NewRequiredPropertyFromMetadata.cs
@@ -79,4 +79,4 @@ public void UpcastJson_Should_BeForwardCompatible()
         @event.ClientId.Should().Be(oldEvent.ClientId);
         @event.InitializedBy.Should().Be(eventMetadata.UserId);
     }
-}
+}