OptionalStringCoding

Author: tomerd

Sources/AWSLambdaEvents/SQS.swift

@@ -32,7 +32,8 @@ public enum SQS {
 
         public let messageId: String
         public let receiptHandle: String
-        public let body: String?
+        @OptionalStringCoding
+        public var body: String?
         public let md5OfBody: String
         public let md5OfMessageAttributes: String?
         public let attributes: [String: String]
@@ -56,22 +57,6 @@ extension SQS.Message: Decodable {
         case eventSource
         case awsRegion
     }
-
-    public init(from decoder: Decoder) throws {
-        let container = try decoder.container(keyedBy: CodingKeys.self)
-        self.messageId = try container.decode(String.self, forKey: .messageId)
-        self.receiptHandle = try container.decode(String.self, forKey: .receiptHandle)
-        self.md5OfBody = try container.decode(String.self, forKey: .md5OfBody)
-        self.md5OfMessageAttributes = try container.decodeIfPresent(String.self, forKey: .md5OfMessageAttributes)
-        self.attributes = try container.decode([String: String].self, forKey: .attributes)
-        self.messageAttributes = try container.decode([String: Attribute].self, forKey: .messageAttributes)
-        self.eventSourceArn = try container.decode(String.self, forKey: .eventSourceArn)
-        self.eventSource = try container.decode(String.self, forKey: .eventSource)
-        self.awsRegion = try container.decode(AWSRegion.self, forKey: .awsRegion)
-
-        let body = try container.decode(String?.self, forKey: .body)
-        self.body = body != "" ? body : nil
-    }
 }
 
 extension SQS.Message.Attribute: Equatable {}

Sources/AWSLambdaEvents/Utils/OptionalStringWrapper.swift

@@ -0,0 +1,38 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the SwiftAWSLambdaRuntime open source project
+//
+// Copyright (c) 2017-2020 Apple Inc. and the SwiftAWSLambdaRuntime project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of SwiftAWSLambdaRuntime project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+@propertyWrapper
+public struct OptionalStringCoding: Decodable {
+    public let wrappedValue: String?
+
+    public init(wrappedValue: String?) {
+        self.wrappedValue = wrappedValue
+    }
+
+    public init(from decoder: Decoder) throws {
+        let container = try decoder.singleValueContainer()
+        var maybeString = try container.decode(String?.self)
+        if let string = maybeString, string.count == 0 {
+            maybeString = nil
+        }
+        self.wrappedValue = maybeString
+    }
+}
+
+extension KeyedDecodingContainer {
+    // This is used to override the default decoding behavior for OptionalStringCoding to allow a value to avoid a missing key Error
+    public func decode(_ type: OptionalStringCoding.Type, forKey key: KeyedDecodingContainer<K>.Key) throws -> OptionalStringCoding {
+        try decodeIfPresent(OptionalStringCoding.self, forKey: key) ?? OptionalStringCoding(wrappedValue: nil)
+    }
+}

Tests/AWSLambdaEventsTests/DateWrapperTests.swift renamed to Tests/AWSLambdaEventsTests/Utils/DateWrapperTests.swift

@@ -0,0 +1,74 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the SwiftAWSLambdaRuntime open source project
+//
+// Copyright (c) 2017-2020 Apple Inc. and the SwiftAWSLambdaRuntime project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of SwiftAWSLambdaRuntime project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+@testable import AWSLambdaEvents
+import XCTest
+
+class OptionStaringWrapperTests: XCTestCase {
+    func testMissing() {
+        struct TestEvent: Decodable {
+            @OptionalStringCoding
+            var value: String?
+
+            public enum CodingKeys: String, CodingKey {
+                case value
+            }
+        }
+
+        let json = #"{}"#
+        var event: TestEvent!
+        XCTAssertNoThrow(event = try JSONDecoder().decode(TestEvent.self, from: json.data(using: .utf8)!))
+        XCTAssertNil(event.value)
+    }
+
+    func testNull() {
+        struct TestEvent: Decodable {
+            @OptionalStringCoding
+            var value: String?
+
+            public enum CodingKeys: String, CodingKey {
+                case value
+            }
+        }
+
+        let json = #"{"value": null}"#
+        var event: TestEvent!
+        XCTAssertNoThrow(event = try JSONDecoder().decode(TestEvent.self, from: json.data(using: .utf8)!))
+        XCTAssertNil(event.value)
+    }
+
+    func testEmpty() {
+        struct TestEvent: Decodable {
+            @OptionalStringCoding
+            var value: String?
+        }
+
+        let json = #"{"value": ""}"#
+        var event: TestEvent!
+        XCTAssertNoThrow(event = try JSONDecoder().decode(TestEvent.self, from: json.data(using: .utf8)!))
+        XCTAssertNil(event.value)
+    }
+
+    func testValue() {
+        struct TestEvent: Decodable {
+            @OptionalStringCoding
+            var value: String?
+        }
+
+        let json = #"{"value": "foo"}"#
+        var event: TestEvent!
+        XCTAssertNoThrow(event = try JSONDecoder().decode(TestEvent.self, from: json.data(using: .utf8)!))
+        XCTAssertEqual(event.value, "foo")
+    }
+}