Feature/fails on empty data for decodable

Changelog.md

@@ -1,6 +1,7 @@
 # Next
 ### Added
 - **Breaking Change** Added a `.requestCustomJSONEncodable` case to `Task`. [#1443](https://github.com/Moya/Moya/pull/1443) by [@evgeny-sureev](https://github.com/evgeny-sureev).
+- **Breaking Change** Added `failsOnEmptyData` boolean support for the `Decodable` map functions. [#1508](https://github.com/Moya/Moya/pull/1508) by [@jeroenbb94](https://github.com/Jeroenbb94).
 
 ### Changed
 - **Breaking Change** Updated minimum version of `ReactiveSwift` to 3.0.

Sources/Moya/Response.swift

@@ -121,7 +121,7 @@ public extension Response {
     ///
     /// - parameter atKeyPath: Optional key path at which to parse object.
     /// - parameter using: A `JSONDecoder` instance which is used to decode data to an object.
-    func map<D: Decodable>(_ type: D.Type, atKeyPath keyPath: String? = nil, using decoder: JSONDecoder = JSONDecoder()) throws -> D {
+    func map<D: Decodable>(_ type: D.Type, atKeyPath keyPath: String? = nil, using decoder: JSONDecoder = JSONDecoder(), failsOnEmptyData: Bool = true) throws -> D {
         let serializeToData: (Any) throws -> Data? = { (jsonObject) in
             guard JSONSerialization.isValidJSONObject(jsonObject) else {
                 return nil
@@ -133,9 +133,14 @@ public extension Response {
             }
         }
         let jsonData: Data
-        if let keyPath = keyPath {
-            guard let jsonObject = (try mapJSON() as? NSDictionary)?.value(forKeyPath: keyPath) else {
-                throw MoyaError.jsonMapping(self)
+        keyPathCheck: if let keyPath = keyPath {
+            guard let jsonObject = (try mapJSON(failsOnEmptyData: failsOnEmptyData) as? NSDictionary)?.value(forKeyPath: keyPath) else {
+                if failsOnEmptyData {
+                    throw MoyaError.jsonMapping(self)
+                } else {
+                    jsonData = data
+                    break keyPathCheck
+                }
             }
 
             if let data = try serializeToData(jsonObject) {
@@ -158,6 +163,13 @@ public extension Response {
             jsonData = data
         }
         do {
+            if jsonData.count < 1 && !failsOnEmptyData {
+                if let emptyJSONObjectData = "{}".data(using: .utf8), let emptyDecodableValue = try? decoder.decode(D.self, from: emptyJSONObjectData) {
+                    return emptyDecodableValue
+                } else if let emptyJSONArrayData = "[{}]".data(using: .utf8), let emptyDecodableValue = try? decoder.decode(D.self, from: emptyJSONArrayData) {
+                    return emptyDecodableValue
+                }
+            }
             return try decoder.decode(D.self, from: jsonData)
         } catch let error {
             throw MoyaError.objectMapping(error, self)

Sources/ReactiveMoya/SignalProducer+Response.swift

@@ -54,9 +54,9 @@ extension SignalProducerProtocol where Value == Response, Error == MoyaError {
     }
 
     /// Maps received data at key path into a Decodable object. If the conversion fails, the signal errors.
-    public func map<D: Decodable>(_ type: D.Type, atKeyPath keyPath: String? = nil, using decoder: JSONDecoder = JSONDecoder()) -> SignalProducer<D, MoyaError> {
+    public func map<D: Decodable>(_ type: D.Type, atKeyPath keyPath: String? = nil, using decoder: JSONDecoder = JSONDecoder(), failsOnEmptyData: Bool = true) -> SignalProducer<D, MoyaError> {
         return producer.flatMap(.latest) { response -> SignalProducer<D, MoyaError> in
-            return unwrapThrowable { try response.map(type, atKeyPath: keyPath, using: decoder) }
+            return unwrapThrowable { try response.map(type, atKeyPath: keyPath, using: decoder, failsOnEmptyData: failsOnEmptyData) }
         }
     }
 }

Sources/RxMoya/Observable+Response.swift

@@ -54,9 +54,9 @@ extension ObservableType where E == Response {
     }
 
     /// Maps received data at key path into a Decodable object. If the conversion fails, the signal errors.
-    public func map<D: Decodable>(_ type: D.Type, atKeyPath keyPath: String? = nil, using decoder: JSONDecoder = JSONDecoder()) -> Observable<D> {
+    public func map<D: Decodable>(_ type: D.Type, atKeyPath keyPath: String? = nil, using decoder: JSONDecoder = JSONDecoder(), failsOnEmptyData: Bool = true) -> Observable<D> {
         return flatMap { response -> Observable<D> in
-            return Observable.just(try response.map(type, atKeyPath: keyPath, using: decoder))
+            return Observable.just(try response.map(type, atKeyPath: keyPath, using: decoder, failsOnEmptyData: failsOnEmptyData))
         }
     }
 }

Sources/RxMoya/Single+Response.swift

@@ -54,9 +54,9 @@ extension PrimitiveSequence where TraitType == SingleTrait, ElementType == Respo
     }
 
     /// Maps received data at key path into a Decodable object. If the conversion fails, the signal errors.
-    public func map<D: Decodable>(_ type: D.Type, atKeyPath keyPath: String? = nil, using decoder: JSONDecoder = JSONDecoder()) -> Single<D> {
+    public func map<D: Decodable>(_ type: D.Type, atKeyPath keyPath: String? = nil, using decoder: JSONDecoder = JSONDecoder(), failsOnEmptyData: Bool = true) -> Single<D> {
         return flatMap { response -> Single<D> in
-            return Single.just(try response.map(type, atKeyPath: keyPath, using: decoder))
+            return Single.just(try response.map(type, atKeyPath: keyPath, using: decoder, failsOnEmptyData: failsOnEmptyData))
         }
     }
 }

Tests/.swiftlint.yml

@@ -6,6 +6,10 @@ disabled_rules:
   - force_try
   - function_body_length
   - cyclomatic_complexity
+  - type_body_length
 
 opt_in_rules:
   - empty_count
+
+file_length:
+  warning: 1000

Tests/Observable+MoyaSpec.swift

@@ -309,6 +309,30 @@ class ObservableMoyaSpec: QuickSpec {
                 expect(receivedObjects?.count) == 3
                 expect(receivedObjects?.map { $0.title }) == ["Hello, Moya!", "Hello, Moya!", "Hello, Moya!"]
             }
+            it("maps empty data to a decodable object with optional properties") {
+                let observable = Response(statusCode: 200, data: Data()).asObservable()
+
+                var receivedObjects: OptionalIssue?
+                _ = observable.map(OptionalIssue.self, using: decoder, failsOnEmptyData: false).subscribe(onNext: { object in
+                    receivedObjects = object
+                })
+                expect(receivedObjects).notTo(beNil())
+                expect(receivedObjects?.title).to(beNil())
+                expect(receivedObjects?.createdAt).to(beNil())
+            }
+
+            it("maps empty data to a decodable array with optional properties") {
+                let observable = Response(statusCode: 200, data: Data()).asObservable()
+
+                var receivedObjects: [OptionalIssue]?
+                _ = observable.map([OptionalIssue].self, using: decoder, failsOnEmptyData: false).subscribe(onNext: { object in
+                    receivedObjects = object
+                })
+                expect(receivedObjects).notTo(beNil())
+                expect(receivedObjects?.count) == 1
+                expect(receivedObjects?.first?.title).to(beNil())
+                expect(receivedObjects?.first?.createdAt).to(beNil())
+            }
 
             context("when using key path mapping") {
                 it("maps data representing a json to a decodable object") {
@@ -344,6 +368,31 @@ class ObservableMoyaSpec: QuickSpec {
                     expect(receivedObjects?.first?.createdAt) == formatter.date(from: "1995-01-14T12:34:56")!
                 }
 
+                it("maps empty data to a decodable object with optional properties") {
+                    let observable = Response(statusCode: 200, data: Data()).asObservable()
+
+                    var receivedObjects: OptionalIssue?
+                    _ = observable.map(OptionalIssue.self, atKeyPath: "issue", using: decoder, failsOnEmptyData: false).subscribe(onNext: { object in
+                        receivedObjects = object
+                    })
+                    expect(receivedObjects).notTo(beNil())
+                    expect(receivedObjects?.title).to(beNil())
+                    expect(receivedObjects?.createdAt).to(beNil())
+                }
+
+                it("maps empty data to a decodable array with optional properties") {
+                    let observable = Response(statusCode: 200, data: Data()).asObservable()
+
+                    var receivedObjects: [OptionalIssue]?
+                    _ = observable.map([OptionalIssue].self, atKeyPath: "issue", using: decoder, failsOnEmptyData: false).subscribe(onNext: { object in
+                        receivedObjects = object
+                    })
+                    expect(receivedObjects).notTo(beNil())
+                    expect(receivedObjects?.count) == 1
+                    expect(receivedObjects?.first?.title).to(beNil())
+                    expect(receivedObjects?.first?.createdAt).to(beNil())
+                }
+
                 it("map Int data to an Int value") {
                     let json: [String: Any] = ["count": 1]
                     guard let data = try? JSONSerialization.data(withJSONObject: json, options: .prettyPrinted) else {

Tests/SignalProducer+MoyaSpec.swift

@@ -295,6 +295,31 @@ class SignalProducerMoyaSpec: QuickSpec {
                 expect(receivedObjects?.map { $0.title }) == ["Hello, Moya!", "Hello, Moya!", "Hello, Moya!"]
             }
 
+            it("maps empty data to a decodable object with optional properties") {
+                let signal = signalSendingData(Data())
+
+                var receivedObjects: OptionalIssue?
+                _ = signal.map(OptionalIssue.self, using: decoder, failsOnEmptyData: false).startWithResult { result in
+                    receivedObjects = result.value
+                }
+                expect(receivedObjects).notTo(beNil())
+                expect(receivedObjects?.title).to(beNil())
+                expect(receivedObjects?.createdAt).to(beNil())
+            }
+
+            it("maps empty data to a decodable array with optional properties") {
+                let signal = signalSendingData(Data())
+
+                var receivedObjects: [OptionalIssue]?
+                _ = signal.map([OptionalIssue].self, using: decoder, failsOnEmptyData: false).startWithResult { result in
+                    receivedObjects = result.value
+                }
+                expect(receivedObjects).notTo(beNil())
+                expect(receivedObjects?.count) == 1
+                expect(receivedObjects?.first?.title).to(beNil())
+                expect(receivedObjects?.first?.createdAt).to(beNil())
+            }
+
             context("when using key path mapping") {
                 it("maps data representing a json to a decodable object") {
                     let json: [String: Any] = ["issue": json] // nested json
@@ -329,6 +354,31 @@ class SignalProducerMoyaSpec: QuickSpec {
                     expect(receivedObjects?.first?.createdAt) == formatter.date(from: "1995-01-14T12:34:56")!
                 }
 
+                it("maps empty data to a decodable object with optional properties") {
+                    let signal = signalSendingData(Data())
+
+                    var receivedObjects: OptionalIssue?
+                    _ = signal.map(OptionalIssue.self, atKeyPath: "issue", using: decoder, failsOnEmptyData: false).startWithResult { result in
+                        receivedObjects = result.value
+                    }
+                    expect(receivedObjects).notTo(beNil())
+                    expect(receivedObjects?.title).to(beNil())
+                    expect(receivedObjects?.createdAt).to(beNil())
+                }
+
+                it("maps empty data to a decodable array with optional properties") {
+                    let signal = signalSendingData(Data())
+
+                    var receivedObjects: [OptionalIssue]?
+                    _ = signal.map([OptionalIssue].self, atKeyPath: "issue", using: decoder, failsOnEmptyData: false).startWithResult { result in
+                        receivedObjects = result.value
+                    }
+                    expect(receivedObjects).notTo(beNil())
+                    expect(receivedObjects?.count) == 1
+                    expect(receivedObjects?.first?.title).to(beNil())
+                    expect(receivedObjects?.first?.createdAt).to(beNil())
+                }
+
                 it("map Int data to an Int value") {
                     let json: [String: Any] = ["count": 1]
                     guard let data = try? JSONSerialization.data(withJSONObject: json, options: .prettyPrinted) else {

Tests/Single+MoyaSpec.swift

@@ -305,6 +305,31 @@ class SingleMoyaSpec: QuickSpec {
                 expect(receivedObjects?.map { $0.title }) == ["Hello, Moya!", "Hello, Moya!", "Hello, Moya!"]
             }
 
+            it("maps empty data to a decodable object with optional properties") {
+                let single = Response(statusCode: 200, data: Data()).asSingle()
+
+                var receivedObjects: OptionalIssue?
+                _ = single.map(OptionalIssue.self, using: decoder, failsOnEmptyData: false).subscribe(onSuccess: { object in
+                    receivedObjects = object
+                })
+                expect(receivedObjects).notTo(beNil())
+                expect(receivedObjects?.title).to(beNil())
+                expect(receivedObjects?.createdAt).to(beNil())
+            }
+
+            it("maps empty data to a decodable array with optional properties") {
+                let single = Response(statusCode: 200, data: Data()).asSingle()
+
+                var receivedObjects: [OptionalIssue]?
+                _ = single.map([OptionalIssue].self, using: decoder, failsOnEmptyData: false).subscribe(onSuccess: { object in
+                    receivedObjects = object
+                })
+                expect(receivedObjects).notTo(beNil())
+                expect(receivedObjects?.count) == 1
+                expect(receivedObjects?.first?.title).to(beNil())
+                expect(receivedObjects?.first?.createdAt).to(beNil())
+            }
+
             context("when using key path mapping") {
                 it("maps data representing a json to a decodable object") {
                     let json: [String: Any] = ["issue": json] // nested json
@@ -339,6 +364,31 @@ class SingleMoyaSpec: QuickSpec {
                     expect(receivedObjects?.first?.createdAt) == formatter.date(from: "1995-01-14T12:34:56")!
                 }
 
+                it("maps empty data to a decodable object with optional properties") {
+                    let single = Response(statusCode: 200, data: Data()).asSingle()
+
+                    var receivedObjects: OptionalIssue?
+                    _ = single.map(OptionalIssue.self, atKeyPath: "issue", using: decoder, failsOnEmptyData: false).subscribe(onSuccess: { object in
+                        receivedObjects = object
+                    })
+                    expect(receivedObjects).notTo(beNil())
+                    expect(receivedObjects?.title).to(beNil())
+                    expect(receivedObjects?.createdAt).to(beNil())
+                }
+
+                it("maps empty data to a decodable array with optional properties") {
+                    let single = Response(statusCode: 200, data: Data()).asSingle()
+
+                    var receivedObjects: [OptionalIssue]?
+                    _ = single.map([OptionalIssue].self, atKeyPath: "issue", using: decoder, failsOnEmptyData: false).subscribe(onSuccess: { object in
+                        receivedObjects = object
+                    })
+                    expect(receivedObjects).notTo(beNil())
+                    expect(receivedObjects?.count) == 1
+                    expect(receivedObjects?.first?.title).to(beNil())
+                    expect(receivedObjects?.first?.createdAt).to(beNil())
+                }
+
                 it("map Int data to an Int value") {
                     let json: [String: Any] = ["count": 1]
                     guard let data = try? JSONSerialization.data(withJSONObject: json, options: .prettyPrinted) else {

Tests/TestHelpers.swift

@@ -51,8 +51,7 @@ extension GitHub: TargetType {
 }
 
 extension GitHub: Equatable {
-
-    static func ==(lhs: GitHub, rhs: GitHub) -> Bool {
+    static func == (lhs: GitHub, rhs: GitHub) -> Bool {
         switch (lhs, rhs) {
         case (.zen, .zen): return true
         case let (.userProfile(username1), .userProfile(username2)): return username1 == username2
@@ -233,3 +232,9 @@ struct Issue: Codable {
         case rating
     }
 }
+
+// A fixture for testing optional Decodable mapping
+struct OptionalIssue: Codable {
+    let title: String?
+    let createdAt: Date?
+}

docs/Examples/Response.md

@@ -214,8 +214,9 @@ struct User: Decodable {
 }
 ```
 
-Moya allows us to easily get our `User` from the response with the `map<D: Decodable>(_: D.Type, atKeyPath: String?, using: JSONDecoder)` extension.
+Moya allows us to easily get our `User` from the response with the `map<D: Decodable>(_: D.Type, atKeyPath: String?, using: JSONDecoder, failsOnEmptyData: Bool)` extension.
 Both `atKeyPath` and `using` are optional, meaning in most cases you'll use `map(_:)`.
+The `failsOnEmptyData` property (default: true), describes whether it should throw an error when data is empty or simply return `Decodable` initialized with nil (note: your object must allow optionals or you'll still get thrown an error).
 A basic example would be:
 
 ```swift
@@ -337,3 +338,70 @@ provider.rx.request(.users)
     }
 }
 ```
+
+The above assumes your backend always returns data and if it doesn't, throwns an error.
+But if you don't want to receive an error, we can set `failsOnEmptyData` to false.
+
+The data returned looks like this:
+
+```json
+{
+  "users": []
+}
+```
+
+Our updated `User` type looks like this:
+
+```swift
+struct User: Decodable {
+    let id: String?
+    let firstName: String?
+    let lastName: String?
+    let updated: Date?
+}
+```
+
+Our handling of the result now has to do slightly more:
+
+```swift
+provider.request(.user) { result in
+    switch result {
+    case let .success(moyaResponse):
+        do {
+            let filteredResponse = try moyaResponse.filterSuccessfulStatusCodes()
+            let decoder = JSONDecoder()
+            decoder.dateDecodingStrategy = .secondsSince1970
+            let users = try filteredResponse.map([User].self, atKeyPath: "users", using: decoder, failsOnEmptyData: false) // user is of type [User]
+            // Because the failsOnEmptyData is false and our user object allows optional, our array got initialized with an empty User object
+            // Do something with your users.
+        }
+        catch let error {
+            // Here we get either statusCode error or objectMapping error.
+            // TODO: handle the error == best. comment. ever.
+        }
+    case let .failure(error):
+        // TODO: handle the error == best. comment. ever.
+    }
+}
+```
+
+In `RxSwift` this could look something like:
+
+```swift
+let decoder = JSONDecoder()
+decoder.dateDecodingStrategy = .secondsSince1970
+provider.rx.request(.users)
+    .filterSuccessfulStatusCodes()
+    .map([User].self, atKeyPath: "users", using: decoder, failsOnEmptyData: false)
+    .subscribe { event in
+        switch event {
+        case .success(let users):
+            // Notice that now we do not get a Response object anymore but rather an array of User objects
+            // Because the failsOnEmptyData is false and our user object allows optional, our array got initialized with an empty User object
+            // do something with the user
+        case .error(let error):
+            // handle the error, which can be an underlying error, a status code error, or an object mapping error
+        }
+    }
+}
+```