Add [DynamoDBEvent] annotation attribute and source generator support

Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Diagnostics/DiagnosticDescriptors.cs

@@ -242,5 +242,12 @@ public static class DiagnosticDescriptors
             category: "AWSLambdaCSharpGenerator",
             DiagnosticSeverity.Error,
             isEnabledByDefault: true);
+
+        public static readonly DiagnosticDescriptor InvalidDynamoDBEventAttribute = new DiagnosticDescriptor(id: "AWSLambda0132",
+            title: "Invalid DynamoDBEventAttribute",
+            messageFormat: "Invalid DynamoDBEventAttribute encountered: {0}",
+            category: "AWSLambdaCSharpGenerator",
+            DiagnosticSeverity.Error,
+            isEnabledByDefault: true);
     }
 }

Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Models/Attributes/AttributeModelBuilder.cs

@@ -1,5 +1,6 @@
 using System;
 using Amazon.Lambda.Annotations.APIGateway;
+using Amazon.Lambda.Annotations.DynamoDB;
 using Amazon.Lambda.Annotations.SQS;
 using Microsoft.CodeAnalysis;
 
@@ -90,6 +91,15 @@ public static AttributeModel Build(AttributeData att, GeneratorExecutionContext
                     Type = TypeModelBuilder.Build(att.AttributeClass, context)
                 };
             }
+            else if (att.AttributeClass.Equals(context.Compilation.GetTypeByMetadataName(TypeFullNames.DynamoDBEventAttribute), SymbolEqualityComparer.Default))
+            {
+                var data = DynamoDBEventAttributeBuilder.Build(att);
+                model = new AttributeModel<DynamoDBEventAttribute>
+                {
+                    Data = data,
+                    Type = TypeModelBuilder.Build(att.AttributeClass, context)
+                };
+            }
             else if (att.AttributeClass.Equals(context.Compilation.GetTypeByMetadataName(TypeFullNames.HttpApiAuthorizerAttribute), SymbolEqualityComparer.Default))
             {
                 var data = HttpApiAuthorizerAttributeBuilder.Build(att);

Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Models/Attributes/DynamoDBEventAttributeBuilder.cs

@@ -0,0 +1,52 @@
+using Amazon.Lambda.Annotations.DynamoDB;
+using Microsoft.CodeAnalysis;
+using System;
+
+namespace Amazon.Lambda.Annotations.SourceGenerator.Models.Attributes
+{
+    /// <summary>
+    /// Builder for <see cref="DynamoDBEventAttribute"/>.
+    /// </summary>
+    public class DynamoDBEventAttributeBuilder
+    {
+        public static DynamoDBEventAttribute Build(AttributeData att)
+        {
+            if (att.ConstructorArguments.Length != 1)
+            {
+                throw new NotSupportedException($"{TypeFullNames.DynamoDBEventAttribute} must have constructor with 1 argument.");
+            }
+            var stream = att.ConstructorArguments[0].Value as string;
+            var data = new DynamoDBEventAttribute(stream);
+
+            foreach (var pair in att.NamedArguments)
+            {
+                if (pair.Key == nameof(data.ResourceName) && pair.Value.Value is string resourceName)
+                {
+                    data.ResourceName = resourceName;
+                }
+                if (pair.Key == nameof(data.BatchSize) && pair.Value.Value is uint batchSize)
+                {
+                    data.BatchSize = batchSize;
+                }
+                else if (pair.Key == nameof(data.StartingPosition) && pair.Value.Value is string startingPosition)
+                {
+                    data.StartingPosition = startingPosition;
+                }
+                else if (pair.Key == nameof(data.Enabled) && pair.Value.Value is bool enabled)
+                {
+                    data.Enabled = enabled;
+                }
+                else if (pair.Key == nameof(data.MaximumBatchingWindowInSeconds) && pair.Value.Value is uint maximumBatchingWindowInSeconds)
+                {
+                    data.MaximumBatchingWindowInSeconds = maximumBatchingWindowInSeconds;
+                }
+                else if (pair.Key == nameof(data.Filters) && pair.Value.Value is string filters)
+                {
+                    data.Filters = filters;
+                }
+            }
+
+            return data;
+        }
+    }
+}

Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Models/EventTypeBuilder.cs

@@ -26,6 +26,10 @@ public static HashSet<EventType> Build(IMethodSymbol lambdaMethodSymbol,
                 {
                     events.Add(EventType.SQS);
                 }
+                else if (attribute.AttributeClass.ToDisplayString() == TypeFullNames.DynamoDBEventAttribute)
+                {
+                    events.Add(EventType.DynamoDB);
+                }
                 else if (attribute.AttributeClass.ToDisplayString() == TypeFullNames.HttpApiAuthorizerAttribute
                     || attribute.AttributeClass.ToDisplayString() == TypeFullNames.RestApiAuthorizerAttribute)
                 {

Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/SyntaxReceiver.cs

@@ -21,7 +21,8 @@ internal class SyntaxReceiver : ISyntaxContextReceiver
             { "RestApiAuthorizerAttribute", "RestApiAuthorizer" },
             { "HttpApiAttribute", "HttpApi" },
             { "RestApiAttribute", "RestApi" },
-            { "SQSEventAttribute", "SQSEvent" }
+            { "SQSEventAttribute", "SQSEvent" },
+            { "DynamoDBEventAttribute", "DynamoDBEvent" }
         };
 
         public List<MethodDeclarationSyntax> LambdaMethods { get; } = new List<MethodDeclarationSyntax>();

Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/TypeFullNames.cs

@@ -46,6 +46,9 @@ public static class TypeFullNames
         public const string SQSBatchResponse = "Amazon.Lambda.SQSEvents.SQSBatchResponse";
         public const string SQSEventAttribute = "Amazon.Lambda.Annotations.SQS.SQSEventAttribute";
 
+        public const string DynamoDBEvent = "Amazon.Lambda.DynamoDBEvents.DynamoDBEvent";
+        public const string DynamoDBEventAttribute = "Amazon.Lambda.Annotations.DynamoDB.DynamoDBEventAttribute";
+
         public const string LambdaSerializerAttribute = "Amazon.Lambda.Core.LambdaSerializerAttribute";
         public const string DefaultLambdaSerializer = "Amazon.Lambda.Serialization.SystemTextJson.DefaultLambdaJsonSerializer";
 
@@ -67,7 +70,8 @@ public static class TypeFullNames
         {
             RestApiAttribute,
             HttpApiAttribute,
-            SQSEventAttribute
+            SQSEventAttribute,
+            DynamoDBEventAttribute
         };
     }
 }

Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Validation/LambdaFunctionValidator.cs

@@ -2,6 +2,7 @@
 using Amazon.Lambda.Annotations.SourceGenerator.Extensions;
 using Amazon.Lambda.Annotations.SourceGenerator.Models;
 using Amazon.Lambda.Annotations.SourceGenerator.Models.Attributes;
+using Amazon.Lambda.Annotations.DynamoDB;
 using Amazon.Lambda.Annotations.SQS;
 using Microsoft.CodeAnalysis;
 using System.Collections.Generic;
@@ -59,6 +60,7 @@ internal static bool ValidateFunction(GeneratorExecutionContext context, IMethod
             // Validate Events
             ValidateApiGatewayEvents(lambdaFunctionModel, methodLocation, diagnostics);
             ValidateSqsEvents(lambdaFunctionModel, methodLocation, diagnostics);
+            ValidateDynamoDBEvents(lambdaFunctionModel, methodLocation, diagnostics);
 
             return ReportDiagnostics(diagnosticReporter, diagnostics);
         }
@@ -86,6 +88,16 @@ internal static bool ValidateDependencies(GeneratorExecutionContext context, IMe
                 }
             }
 
+            // Check for references to "Amazon.Lambda.DynamoDBEvents" if the Lambda method is annotated with DynamoDBEvent attribute.
+            if (lambdaMethodSymbol.HasAttribute(context, TypeFullNames.DynamoDBEventAttribute))
+            {
+                if (context.Compilation.ReferencedAssemblyNames.FirstOrDefault(x => x.Name == "Amazon.Lambda.DynamoDBEvents") == null)
+                {
+                    diagnosticReporter.Report(Diagnostic.Create(DiagnosticDescriptors.MissingDependencies, methodLocation, "Amazon.Lambda.DynamoDBEvents"));
+                    return false;
+                }
+            }
+
             return true;
         }
 
@@ -268,6 +280,45 @@ private static void ValidateSqsEvents(LambdaFunctionModel lambdaFunctionModel, L
             }
         }
 
+        private static void ValidateDynamoDBEvents(LambdaFunctionModel lambdaFunctionModel, Location methodLocation, List<Diagnostic> diagnostics)
+        {
+            if (!lambdaFunctionModel.LambdaMethod.Events.Contains(EventType.DynamoDB))
+            {
+                return;
+            }
+
+            // Validate DynamoDBEventAttributes
+            foreach (var att in lambdaFunctionModel.Attributes)
+            {
+                if (att.Type.FullName != TypeFullNames.DynamoDBEventAttribute)
+                    continue;
+
+                var dynamoDBEventAttribute = ((AttributeModel<DynamoDBEventAttribute>)att).Data;
+                var validationErrors = dynamoDBEventAttribute.Validate();
+                validationErrors.ForEach(errorMessage => diagnostics.Add(Diagnostic.Create(DiagnosticDescriptors.InvalidDynamoDBEventAttribute, methodLocation, errorMessage)));
+            }
+
+            // Validate method parameters - When using DynamoDBEventAttribute, the method signature must be (DynamoDBEvent evnt) or (DynamoDBEvent evnt, ILambdaContext context)
+            var parameters = lambdaFunctionModel.LambdaMethod.Parameters;
+            if (parameters.Count == 0 ||
+                parameters.Count > 2 ||
+                (parameters.Count == 1 && parameters[0].Type.FullName != TypeFullNames.DynamoDBEvent) ||
+                (parameters.Count == 2 && (parameters[0].Type.FullName != TypeFullNames.DynamoDBEvent || parameters[1].Type.FullName != TypeFullNames.ILambdaContext)))
+            {
+                var errorMessage = $"When using the {nameof(DynamoDBEventAttribute)}, the Lambda method can accept at most 2 parameters. " +
+                    $"The first parameter is required and must be of type {TypeFullNames.DynamoDBEvent}. " +
+                    $"The second parameter is optional and must be of type {TypeFullNames.ILambdaContext}.";
+                diagnostics.Add(Diagnostic.Create(DiagnosticDescriptors.InvalidLambdaMethodSignature, methodLocation, errorMessage));
+            }
+
+            // Validate method return type - When using DynamoDBEventAttribute, the return type must be either void or Task
+            if (!lambdaFunctionModel.LambdaMethod.ReturnsVoid && !lambdaFunctionModel.LambdaMethod.ReturnsVoidTask)
+            {
+                var errorMessage = $"When using the {nameof(DynamoDBEventAttribute)}, the Lambda method can return either void or {TypeFullNames.Task}";
+                diagnostics.Add(Diagnostic.Create(DiagnosticDescriptors.InvalidLambdaMethodSignature, methodLocation, errorMessage));
+            }
+        }
+
         private static bool ReportDiagnostics(DiagnosticReporter diagnosticReporter, List<Diagnostic> diagnostics)
         {
             var isValid = true;

Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Writers/CloudFormationWriter.cs

@@ -1,4 +1,5 @@
 using Amazon.Lambda.Annotations.APIGateway;
+using Amazon.Lambda.Annotations.DynamoDB;
 using Amazon.Lambda.Annotations.SourceGenerator.Diagnostics;
 using Amazon.Lambda.Annotations.SourceGenerator.FileIO;
 using Amazon.Lambda.Annotations.SourceGenerator.Models;
@@ -221,6 +222,10 @@ private void ProcessLambdaFunctionEventAttributes(ILambdaFunctionSerializable la
                         eventName = ProcessSqsAttribute(lambdaFunction, sqsAttributeModel.Data, currentSyncedEventProperties);
                         currentSyncedEvents.Add(eventName);
                         break;
+                    case AttributeModel<DynamoDBEventAttribute> dynamoDBAttributeModel:
+                        eventName = ProcessDynamoDBAttribute(lambdaFunction, dynamoDBAttributeModel.Data, currentSyncedEventProperties);
+                        currentSyncedEvents.Add(eventName);
+                        break;
                 }
             }
 
@@ -600,6 +605,68 @@ private string ProcessSqsAttribute(ILambdaFunctionSerializable lambdaFunction, S
         /// Writes all properties associated with <see cref="LambdaFunctionRoleAttribute"/> to the serverless template.
         /// </summary>
 
+        /// <summary>
+        /// Writes all properties associated with <see cref="DynamoDBEventAttribute"/> to the serverless template.
+        /// </summary>
+        private string ProcessDynamoDBAttribute(ILambdaFunctionSerializable lambdaFunction, DynamoDBEventAttribute att, Dictionary<string, List<string>> syncedEventProperties)
+        {
+            var eventName = att.ResourceName;
+            var eventPath = $"Resources.{lambdaFunction.ResourceName}.Properties.Events.{eventName}";
+
+            _templateWriter.SetToken($"{eventPath}.Type", "DynamoDB");
+
+            // Stream
+            _templateWriter.RemoveToken($"{eventPath}.Properties.Stream");
+            if (!att.Stream.StartsWith("@"))
+            {
+                SetEventProperty(syncedEventProperties, lambdaFunction.ResourceName, eventName, "Stream", att.Stream);
+            }
+            else
+            {
+                var resource = att.Stream.Substring(1);
+                if (_templateWriter.Exists($"{PARAMETERS}.{resource}"))
+                    SetEventProperty(syncedEventProperties, lambdaFunction.ResourceName, eventName, $"Stream.{REF}", resource);
+                else
+                    SetEventProperty(syncedEventProperties, lambdaFunction.ResourceName, eventName, $"Stream.{GET_ATTRIBUTE}", new List<string> { resource, "StreamArn" }, TokenType.List);
+            }
+
+            // StartingPosition
+            SetEventProperty(syncedEventProperties, lambdaFunction.ResourceName, eventName, "StartingPosition", att.StartingPosition);
+
+            // BatchSize
+            if (att.IsBatchSizeSet)
+            {
+                SetEventProperty(syncedEventProperties, lambdaFunction.ResourceName, eventName, "BatchSize", att.BatchSize);
+            }
+
+            // Enabled
+            if (att.IsEnabledSet)
+            {
+                SetEventProperty(syncedEventProperties, lambdaFunction.ResourceName, eventName, "Enabled", att.Enabled);
+            }
+
+            // MaximumBatchingWindowInSeconds
+            if (att.IsMaximumBatchingWindowInSecondsSet)
+            {
+                SetEventProperty(syncedEventProperties, lambdaFunction.ResourceName, eventName, "MaximumBatchingWindowInSeconds", att.MaximumBatchingWindowInSeconds);
+            }
+
+            // FilterCriteria
+            if (att.IsFiltersSet)
+            {
+                const char SEPERATOR = ';';
+                var filters = att.Filters.Split(SEPERATOR).Select(x => x.Trim()).ToList();
+                var filterList = new List<Dictionary<string, string>>();
+                foreach (var filter in filters)
+                {
+                    filterList.Add(new Dictionary<string, string> { { "Pattern", filter } });
+                }
+                SetEventProperty(syncedEventProperties, lambdaFunction.ResourceName, eventName, "FilterCriteria.Filters", filterList, TokenType.List);
+            }
+
+            return att.ResourceName;
+        }
+
         /// <summary>
         /// Writes the default values for the Lambda function's metadata and properties.
         /// </summary>