feat(configuration): Select encoder/decoder per type (#29)

pjechris · web-flow · commit 60160479d00d · 2026-04-04T15:35:14.000+02:00
diff --git a/Sources/SimpleHTTP/ContentData/ContentDataCoderConfiguration.swift b/Sources/SimpleHTTP/ContentData/ContentDataCoderConfiguration.swift
@@ -0,0 +1,76 @@
+import Foundation
+
+public struct ContentDataCoderConfiguration {
+    public var encoder: ContentDataEncoderConfiguration
+    public var decoder: ContentDataDecoderConfiguration
+    public let defaultType: HTTPContentType
+
+    public init(
+        default: HTTPContentType,
+        encoder: ContentDataEncoderConfiguration,
+        decoder: ContentDataDecoderConfiguration,
+    ) {
+        self.encoder = encoder
+        self.decoder = decoder
+        self.defaultType = `default`
+    }
+
+    public init() {
+        self.init(
+            default: .json,
+            encoder: [
+                .json: JSONEncoder(),
+                .formURLEncoded: FormURLEncoder()
+            ],
+            decoder: [
+                .json: JSONDecoder()
+            ]
+        )
+    }
+}
+
+@dynamicMemberLookup
+public struct ContentDataEncoderConfiguration: ExpressibleByDictionaryLiteral {
+    private var encoders: [HTTPContentType: ContentDataEncoder]
+
+    public init(encoders: [HTTPContentType: ContentDataEncoder]) {
+        self.encoders = encoders
+    }
+
+    public init(dictionaryLiteral elements: (HTTPContentType, ContentDataEncoder)...) {
+        self.init(encoders: Dictionary(uniqueKeysWithValues: elements))
+    }
+
+    public subscript(contentType: HTTPContentType) -> ContentDataEncoder? {
+        get { encoders[contentType] }
+        set { encoders[contentType] = newValue }
+    }
+
+    public subscript(dynamicMember keyPath: KeyPath<HTTPContentType.Type, HTTPContentType>) -> ContentDataEncoder? {
+        get { self[HTTPContentType.self[keyPath: keyPath]] }
+        set { self[HTTPContentType.self[keyPath: keyPath]] = newValue }
+    }
+}
+
+@dynamicMemberLookup
+public struct ContentDataDecoderConfiguration: ExpressibleByDictionaryLiteral {
+    private var decoders: [HTTPContentType: ContentDataDecoder]
+
+    public init(decoders: [HTTPContentType: ContentDataDecoder]) {
+        self.decoders = decoders
+    }
+
+    public init(dictionaryLiteral elements: (HTTPContentType, ContentDataDecoder)...) {
+        self.init(decoders: Dictionary(uniqueKeysWithValues: elements))
+    }
+
+    public subscript(contentType: HTTPContentType) -> ContentDataDecoder? {
+        get { decoders[contentType] }
+        set { decoders[contentType] = newValue }
+    }
+
+    public subscript(dynamicMember keyPath: KeyPath<HTTPContentType.Type, HTTPContentType>) -> ContentDataDecoder? {
+        get { self[HTTPContentType.self[keyPath: keyPath]] }
+        set { self[HTTPContentType.self[keyPath: keyPath]] = newValue }
+    }
+}
diff --git a/Sources/SimpleHTTP/ContentData/FormURL/FormURLEncoder.swift b/Sources/SimpleHTTP/ContentData/FormURL/FormURLEncoder.swift
diff --git a/Sources/SimpleHTTP/ContentData/FormURL/HTTPContentType+FormURL.swift b/Sources/SimpleHTTP/ContentData/FormURL/HTTPContentType+FormURL.swift
diff --git a/Sources/SimpleHTTP/Session/Session.swift b/Sources/SimpleHTTP/Session/Session.swift
@@ -44,8 +44,12 @@ public class Session {
     public func response<Output: Decodable>(for request: Request<Output>) async throws -> Output {
         let result = try await dataPublisher(for: request)
 
+        guard let decoder = config.data.decoder[result.contentType] else {
+            throw SessionConfigurationError.missingDecoder(result.contentType)
+        }
+
         do {
-            let decodedOutput = try config.decoder.decode(Output.self, from: result.data)
+            let decodedOutput = try decoder.decode(Output.self, from: result.data)
             let output = try config.interceptor.adaptOutput(decodedOutput, for: result.request)
 
             log(.success(output), for: result.request)
@@ -67,15 +71,31 @@ public class Session {
 extension Session {
     private func dataPublisher<Output>(for request: Request<Output>) async throws -> Response<Output> {
         let modifiedRequest = try await config.interceptor.adaptRequest(request)
-        let urlRequest = try modifiedRequest
-            .toURLRequest(encoder: config.encoder, relativeTo: baseURL, accepting: config.decoder)
+        let requestContentType = modifiedRequest.headers.contentType ?? config.data.defaultType
+        let encoder: ContentDataEncoder?
+
+        // FIXME: we also check body inside toURLRequest
+        switch modifiedRequest.body {
+        case .encodable:
+            encoder = config.data.encoder[requestContentType]
+        case .multipart, .none:
+            // this one is supposed to never be nil
+            encoder = config.data.encoder[config.data.defaultType]
+        }
+
+        guard let encoder else {
+            throw SessionConfigurationError.missingEncoder(requestContentType)
+        }
+
+        let urlRequest = try modifiedRequest.toURLRequest(encoder: encoder, relativeTo: baseURL)
 
         do {
             let result = try await dataTask(urlRequest)
+            let responseContentType = result.response.mimeType.map(HTTPContentType.init(value:)) ?? config.data.defaultType
 
-            try result.validate(errorDecoder: config.errorConverter)
+            try result.validate(errorDecoder: errorDecoder(for: responseContentType))
 
-            return Response(data: result.data, request: modifiedRequest)
+            return Response(data: result.data, contentType: responseContentType, request: modifiedRequest)
         }
         catch {
             self.log(.failure(error), for: modifiedRequest)
@@ -91,9 +111,18 @@ extension Session {
     private func log<Output>(_ response: Result<Output, Error>, for request: Request<Output>) {
         config.interceptor.receivedResponse(response, for: request)
     }
+
+    private func errorDecoder(for contentType: HTTPContentType) throws -> DataErrorDecoder? {
+        guard let converter = config.errorConverter else {
+            return nil
+        }
+
+        return { data in try converter(data, contentType) }
+    }
 }
 
 private struct Response<Output> {
     let data: Data
+    let contentType: HTTPContentType
     let request: Request<Output>
 }
diff --git a/Sources/SimpleHTTP/Session/SessionConfiguration.swift b/Sources/SimpleHTTP/Session/SessionConfiguration.swift
@@ -2,44 +2,46 @@ import Foundation
 
 /// a type defining some parameters for a `Session`
 public struct SessionConfiguration {
-    /// encoder to use for request bodies
-    let encoder: ContentDataEncoder
-    /// decoder used to decode http responses
-    let decoder: ContentDataDecoder
+    /// data encoders/decoders configuration per content type
+    let data: ContentDataCoderConfiguration
     /// queue on which to decode data
     let decodingQueue: DispatchQueue
     /// an interceptor to apply custom behavior on the session requests/responses.
     /// To apply multiple interceptors use `ComposeInterceptor`
     let interceptor: Interceptor
-    /// a function decoding data (using `decoder`) as a custom error
-    private(set) var errorConverter: DataErrorDecoder?
+    /// a function decoding data as a custom error given the response content type
+    private(set) var errorConverter: ContentDataErrorDecoder?
 
-    /// - Parameter encoder to use for request bodies
-    /// - Parameter decoder used to decode http responses
+    /// - Parameter data: encoders/decoders configuration per content type
     /// - Parameter decodeQueue: queue on which to decode data
     /// - Parameter interceptors: interceptor list to apply on the session requests/responses
     public init(
-        encoder: ContentDataEncoder = JSONEncoder(),
-        decoder: ContentDataDecoder = JSONDecoder(),
+        data: ContentDataCoderConfiguration = .init(),
         decodingQueue: DispatchQueue = .main,
         interceptors: CompositeInterceptor = []) {
-            self.encoder = encoder
-            self.decoder = decoder
+            self.data = data
             self.decodingQueue = decodingQueue
             self.interceptor = interceptors
         }
 
     /// - Parameter dataError: Error type to use when having error with data
     public init<DataError: Error & Decodable>(
-        encoder: ContentDataEncoder = JSONEncoder(),
-        decoder: ContentDataDecoder = JSONDecoder(),
+        data: ContentDataCoderConfiguration,
         decodingQueue: DispatchQueue = .main,
         interceptors: CompositeInterceptor = [],
         dataError: DataError.Type
     ) {
-        self.init(encoder: encoder, decoder: decoder, decodingQueue: decodingQueue, interceptors: interceptors)
-        self.errorConverter = {
-            try decoder.decode(dataError, from: $0)
+        self.init(data: data, decodingQueue: decodingQueue, interceptors: interceptors)
+        self.errorConverter = { [decoder=data.decoder] data, contentType in
+            guard let decoder = decoder[contentType] else {
+                throw SessionConfigurationError.missingDecoder(contentType)
+            }
+            return try decoder.decode(dataError, from: data)
         }
     }
 }
+
+public enum SessionConfigurationError: Error {
+    case missingEncoder(HTTPContentType)
+    case missingDecoder(HTTPContentType)
+}
diff --git a/Sources/SimpleHTTPFoundation/Foundation/Coder/DataCoder.swift b/Sources/SimpleHTTPFoundation/Foundation/Coder/DataCoder.swift
@@ -24,3 +24,5 @@ public protocol ContentDataDecoder: DataDecoder {
 
 /// A function converting data when a http error occur into a custom error
 public typealias DataErrorDecoder = (Data) throws -> Error
+
+public typealias ContentDataErrorDecoder = (Data, HTTPContentType) throws -> Error
diff --git a/Sources/SimpleHTTPFoundation/HTTP/HTTPHeader.swift b/Sources/SimpleHTTPFoundation/HTTP/HTTPHeader.swift
@@ -31,3 +31,18 @@ extension HTTPHeader {
     public static let proxyAuthorization: Self = "Proxy-Authorization"
     public static let wwwAuthenticate: Self = "WWW-Authenticate"
 }
+
+public extension HTTPHeaderFields {
+    /// - Returns the content type if HTTPHeader.contentType was set
+    var contentType: HTTPContentType? {
+        self[.contentType].map(HTTPContentType.init(value:))
+    }
+
+    func contentType(_ value: HTTPContentType) -> Self {
+        var copy = self
+
+        copy[.contentType] = value.value
+
+        return copy
+    }
+}
diff --git a/Tests/SimpleHTTPTests/ContentData/FormURL/FormURLEncoderTests.swift b/Tests/SimpleHTTPTests/ContentData/FormURL/FormURLEncoderTests.swift
diff --git a/Tests/SimpleHTTPTests/Session/SessionTests.swift b/Tests/SimpleHTTPTests/Session/SessionTests.swift
@@ -3,8 +3,11 @@ import XCTest
 
 class SessionAsyncTests: XCTestCase {
     let baseURL = URL(string: "https://sessionTests.io")!
-    let encoder = JSONEncoder()
-    let decoder = JSONDecoder()
+    let data = ContentDataCoderConfiguration(
+        default: .json,
+        encoder: [.json: JSONEncoder()],
+        decoder: [.json: JSONDecoder()]
+    )
 
     func test_response_responseIsValid_decodedOutputIsReturned() async throws {
         let expectedResponse = Content(value: "response")
@@ -21,7 +24,7 @@ class SessionAsyncTests: XCTestCase {
         let interceptor = InterceptorStub()
         let session = sesssionStub(
             interceptor: [interceptor],
-            data: { URLDataResponse(data: try! JSONEncoder().encode(output), response: .success) }
+            response: { URLDataResponse(data: try! JSONEncoder().encode(output), response: .success) }
         )
 
         interceptor.adaptResponseMock = { _, _ in
@@ -73,7 +76,7 @@ class SessionAsyncTests: XCTestCase {
     func test_response_httpDataHasCustomError_returnCustomError() async throws {
         let session = Session(
             baseURL: baseURL,
-            configuration: SessionConfiguration(encoder: encoder, decoder: decoder, dataError: CustomError.self),
+            configuration: SessionConfiguration(data: data, dataError: CustomError.self),
             dataTask: { _ in
                 URLDataResponse(data: try! JSONEncoder().encode(CustomError()), response: .unauthorized)
             })
@@ -88,11 +91,11 @@ class SessionAsyncTests: XCTestCase {
     }
 
     /// helper to create a session for testing
-    private func sesssionStub(interceptor: CompositeInterceptor = [], data: @escaping () throws -> URLDataResponse)
+    private func sesssionStub(interceptor: CompositeInterceptor = [], response: @escaping () throws -> URLDataResponse)
     -> Session {
-        let config = SessionConfiguration(encoder: encoder, decoder: decoder, interceptors: interceptor)
+        let config = SessionConfiguration(data: data, interceptors: interceptor)
 
-        return Session(baseURL: baseURL, configuration: config, dataTask: { _ in try data() })
+        return Session(baseURL: baseURL, configuration: config, dataTask: { _ in try response() })
     }
 }
 
