[Bug Fix][Amplify API] Fix the bug which fails to update the value to nil (#519)

* debug Model-GraphQL.swift to fix update nil bug

* debug Model-GraphQL.swift to fix update nil bug

* added a unit test

* revert changes in Podfile.lock and Manifest.lock

Author: ruiguoamz

Amplify.xcodeproj/project.pbxproj

@@ -331,6 +331,7 @@
 		B9FAA175238EFC5A009414B4 /* String+Extensions.swift in Sources */ = {isa = PBXBuildFile; fileRef = B9FAA174238EFC59009414B4 /* String+Extensions.swift */; };
 		B9FAA180238FBB5D009414B4 /* Model+Array.swift in Sources */ = {isa = PBXBuildFile; fileRef = B9FAA17F238FBB5D009414B4 /* Model+Array.swift */; };
 		B9FB05F82383740D00DE1FD4 /* DataStoreStatement.swift in Sources */ = {isa = PBXBuildFile; fileRef = B9FB05F72383740D00DE1FD4 /* DataStoreStatement.swift */; };
+		D83C5160248964780091548E /* ModelGraphQLTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = D83C515F248964780091548E /* ModelGraphQLTests.swift */; };
 		FA0173352375F8A5005DDDFC /* LoggingError.swift in Sources */ = {isa = PBXBuildFile; fileRef = FA0173342375F8A5005DDDFC /* LoggingError.swift */; };
 		FA0173372375FAA5005DDDFC /* HubError.swift in Sources */ = {isa = PBXBuildFile; fileRef = FA0173362375FAA5005DDDFC /* HubError.swift */; };
 		FA09337C23844E9F00C2FD5F /* GraphQLOperationRequest.swift in Sources */ = {isa = PBXBuildFile; fileRef = FA09337B23844E9F00C2FD5F /* GraphQLOperationRequest.swift */; };
@@ -1088,6 +1089,7 @@
 		D2A0246D3621B503C915A5D1 /* Pods-AWSPlugins-AWSAuthService-AWSAPICategoryPlugin.release.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-AWSPlugins-AWSAuthService-AWSAPICategoryPlugin.release.xcconfig"; path = "Target Support Files/Pods-AWSPlugins-AWSAuthService-AWSAPICategoryPlugin/Pods-AWSPlugins-AWSAuthService-AWSAPICategoryPlugin.release.xcconfig"; sourceTree = "<group>"; };
 		D5363CAF9EFAA822FED56808 /* Pods_Amplify_AWSPluginsCore_AWSPluginsTestConfigs_AWSPluginsTestCommon.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = Pods_Amplify_AWSPluginsCore_AWSPluginsTestConfigs_AWSPluginsTestCommon.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		D5521D5FA66340943C39C451 /* Pods-Amplify-AmplifyAWSPlugins-AWSPluginsCore-AWSAPICategoryPlugin.debug.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-Amplify-AmplifyAWSPlugins-AWSPluginsCore-AWSAPICategoryPlugin.debug.xcconfig"; path = "Target Support Files/Pods-Amplify-AmplifyAWSPlugins-AWSPluginsCore-AWSAPICategoryPlugin/Pods-Amplify-AmplifyAWSPlugins-AWSPluginsCore-AWSAPICategoryPlugin.debug.xcconfig"; sourceTree = "<group>"; };
+		D83C515F248964780091548E /* ModelGraphQLTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ModelGraphQLTests.swift; sourceTree = "<group>"; };
 		DD2486414D63230FF39130C7 /* Pods-Amplify-AWSPluginsCore.debug.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-Amplify-AWSPluginsCore.debug.xcconfig"; path = "Target Support Files/Pods-Amplify-AWSPluginsCore/Pods-Amplify-AWSPluginsCore.debug.xcconfig"; sourceTree = "<group>"; };
 		DEEB82A328223C60557B75C1 /* Pods-Amplify-AmplifyAWSPlugins-AWSPluginsCore-AWSPinpointAnalyticsPlugin.release.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-Amplify-AmplifyAWSPlugins-AWSPluginsCore-AWSPinpointAnalyticsPlugin.release.xcconfig"; path = "Target Support Files/Pods-Amplify-AmplifyAWSPlugins-AWSPluginsCore-AWSPinpointAnalyticsPlugin/Pods-Amplify-AmplifyAWSPlugins-AWSPluginsCore-AWSPinpointAnalyticsPlugin.release.xcconfig"; sourceTree = "<group>"; };
 		E1306F31E45EE7C6B6048F89 /* Pods-AmplifyAWSPlugins-AWSPluginsCore-AWSS3StoragePlugin-AWSS3StoragePluginTests.release.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-AmplifyAWSPlugins-AWSPluginsCore-AWSS3StoragePlugin-AWSS3StoragePluginTests.release.xcconfig"; path = "Target Support Files/Pods-AmplifyAWSPlugins-AWSPluginsCore-AWSS3StoragePlugin-AWSS3StoragePluginTests/Pods-AmplifyAWSPlugins-AWSPluginsCore-AWSS3StoragePlugin-AWSS3StoragePluginTests.release.xcconfig"; sourceTree = "<group>"; };
@@ -1490,6 +1492,7 @@
 			isa = PBXGroup;
 			children = (
 				2129BE2F2394828A006363A1 /* QueryPredicateGraphQLTests.swift */,
+				D83C515F248964780091548E /* ModelGraphQLTests.swift */,
 			);
 			path = Support;
 			sourceTree = "<group>";
@@ -3966,6 +3969,7 @@
 				6BBECD7423ADA9D100C8DFBE /* AmplifyAWSServiceConfigurationTests.swift in Sources */,
 				2129BE3C2394828B006363A1 /* GraphQLRequestModelTests.swift in Sources */,
 				2183A56523EA4A8400232880 /* GraphQLListQueryTests.swift in Sources */,
+				D83C5160248964780091548E /* ModelGraphQLTests.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

AmplifyPlugins/Core/AWSPluginsCore/Model/Support/Model+GraphQL.swift

@@ -24,7 +24,7 @@ extension Model {
 
             // swiftlint:disable:next syntactic_sugar
             guard case .some(Optional<Any>.some(let value)) = fieldValue ?? nil else {
-                input[name] = nil
+                input.updateValue(nil, forKey: name)
                 return
             }
 

AmplifyPlugins/Core/AWSPluginsCoreTests/Model/Support/ModelGraphQLTests.swift

@@ -0,0 +1,46 @@
+//
+// Copyright 2018-2020 Amazon.com,
+// Inc. or its affiliates. All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+import XCTest
+@testable import Amplify
+@testable import AmplifyTestCommon
+@testable import AWSPluginsCore
+
+class ModelGraphQLTests: XCTestCase {
+
+    /// - Given: a `Model` type
+    /// - When:
+    ///    - the model is of type `Post`
+    ///    - the model is initialized with value except `updatedAt` is set to nil
+    /// - Then:
+    ///    - check if the generated GraphQLInput is valid input:
+    ///      - fields other than `updatedAt` has the correct value in them
+    ///      - `updatedAt` is nil
+    func testPostModelToGraphQLInputSuccess() throws {
+        let date: Temporal.DateTime = .now()
+        let status = PostStatus.published
+        let post = Post(id: "id",
+                        title: "title",
+                        content: "content",
+                        createdAt: date,
+                        draft: true,
+                        rating: 5.0,
+                        status: status)
+
+        let graphQLInput = post.graphQLInput
+
+        XCTAssertEqual(graphQLInput["title"] as? String, post.title)
+        XCTAssertEqual(graphQLInput["content"] as? String, post.content)
+        XCTAssertEqual(graphQLInput["createdAt"] as? String, post.createdAt.iso8601String)
+        XCTAssertEqual(graphQLInput["draft"] as? Bool, post.draft)
+        XCTAssertEqual(graphQLInput["rating"] as? Double, post.rating)
+        XCTAssertEqual(graphQLInput["status"] as? String, status.rawValue)
+
+        XCTAssertTrue(graphQLInput.keys.contains("updatedAt"))
+        XCTAssertNil(graphQLInput["updatedAt"]!)
+    }
+}