Query Encoding Strategy (#18)

* Added a query encoding strategy

* Slightly better semantics

* Added one more test

Author: zac

Sources/Endpoints/Endpoint+URLRequest.swift

@@ -79,6 +79,19 @@ extension Endpoint {
             components.queryItems = urlQueryItems
         }
 
+        switch Self.queryEncodingStrategy {
+        case .default:
+            break
+        case .custom(let encode):
+            components.percentEncodedQuery = urlQueryItems
+                .compactMap(encode)
+                .compactMap { (name, value) in
+                    guard let value else { return nil }
+                    return name + "=" + value
+                }
+                .joined(separator: "&")
+        }
+
         let baseUrl = environment.baseUrl
         guard let url = components.url(relativeTo: baseUrl) else {
             throw EndpointError.invalid(components: components, relativeTo: baseUrl)

Sources/Endpoints/Endpoint.swift

@@ -139,6 +139,9 @@ public protocol Endpoint {
 
     /// The decoder instance to use when decoding the associated ``Endpoint/Response`` type
     static var responseDecoder: ResponseDecoder { get }
+
+    /// A strategy for encoding query parameters. Defaults to `QueryEncodingStrategy.default`
+    static var queryEncodingStrategy: QueryEncodingStrategy { get }
 }
 
 public extension Endpoint where Body == EmptyCodable {
@@ -174,6 +177,17 @@ public extension Endpoint where BodyEncoder == JSONEncoder {
     }
 }
 
+public extension Endpoint {
+    static var queryEncodingStrategy: QueryEncodingStrategy {
+        return .default
+    }
+}
+
+public enum QueryEncodingStrategy {
+    case `default`
+    case custom((URLQueryItem) -> (String, String?)?)
+}
+
 public struct Definition<T: Endpoint> {
 
     /// The HTTP method of the ``Endpoint``

Tests/EndpointsTests/Endpoints/CustomEncodingEndpoint.swift

@@ -0,0 +1,36 @@
+//
+//  CustomEncodingEndpoint.swift
+//  EndpointsTests
+//
+//  Created by Zac White on 9/26/24.
+//  Copyright © 2024 Velos Mobile LLC. All rights reserved.
+//
+
+import Endpoints
+import Foundation
+
+struct CustomEncodingEndpoint: Endpoint {
+    static let definition: Definition<CustomEncodingEndpoint> = Definition(
+        method: .get,
+        path: "/",
+        parameters: [
+            .query("key", path: \ParameterComponents.needsCustomEncoding)
+        ]
+    )
+
+    struct ParameterComponents {
+        let needsCustomEncoding: String
+    }
+
+    typealias Response = Void
+
+    let parameterComponents: ParameterComponents
+
+    static var queryEncodingStrategy: QueryEncodingStrategy {
+        .custom {
+            var characterSet = CharacterSet.urlQueryAllowed
+            characterSet.remove(charactersIn: "+")
+            return ($0.name, $0.value?.addingPercentEncoding(withAllowedCharacters: characterSet))
+        }
+    }
+}

Tests/EndpointsTests/Endpoints/UserEndpoint.swift

@@ -36,6 +36,14 @@ struct UserEndpoint: Endpoint {
         ]
     )
 
+    static var queryEncodingStrategy: QueryEncodingStrategy {
+        .custom {
+            var characterSet = CharacterSet.urlQueryAllowed
+            characterSet.remove(charactersIn: "+")
+            return ($0.name, $0.value?.addingPercentEncoding(withAllowedCharacters: characterSet))
+        }
+    }
+
     typealias Response = Void
 
     struct PathComponents {

Tests/EndpointsTests/EndpointsTests.swift

@@ -61,12 +61,20 @@ class EndpointsTests: XCTestCase {
         XCTAssertEqual(request.httpMethod, "POST")
     }
 
+    func testCustomParameterEncoding() throws {
+        let request = try CustomEncodingEndpoint(
+            parameterComponents: .init(needsCustomEncoding: "++++")
+        ).urlRequest(in: Environment.test)
+
+        XCTAssertEqual(request.url?.query, "key=%2B%2B%2B%2B")
+    }
+
     func testParameterEndpoint() throws {
 
         let request = try UserEndpoint(
             pathComponents: .init(userId: "3"),
             parameterComponents: .init(
-                string: "test:of:thing%asdf",
+                string: "test:of:+thing%asdf",
                 date: Date(),
                 double: 2.3,
                 int: 42,
@@ -81,7 +89,7 @@ class EndpointsTests: XCTestCase {
 
         XCTAssertEqual(request.httpMethod, "GET")
         XCTAssertEqual(request.url?.path, "/hey/3")
-        XCTAssertEqual(request.url?.query, "string=test:of:thing%25asdf&hard_coded_query=true")
+        XCTAssertEqual(request.url?.query, "string=test:of:%2Bthing%25asdf&hard_coded_query=true")
 
         XCTAssertEqual(request.value(forHTTPHeaderField: "HEADER_TYPE"), "test")
         XCTAssertEqual(request.value(forHTTPHeaderField: "HARD_CODED_HEADER"), "test2")
@@ -90,7 +98,7 @@ class EndpointsTests: XCTestCase {
 
         XCTAssertNotNil(request.httpBody)
         XCTAssertTrue(
-            String(data: request.httpBody ?? Data(), encoding: .utf8)?.contains("string=test%3Aof%3Athing%25asdf") ?? false
+            String(data: request.httpBody ?? Data(), encoding: .utf8)?.contains("string=test%3Aof%3A+thing%25asdf") ?? false
         )
         XCTAssertFalse(
             String(data: request.httpBody ?? Data(), encoding: .utf8)?.contains("optional_string") ?? true