Support for associated array query parameters

Sources/Networking/Core/Requestable+Convenience.swift

@@ -55,7 +55,7 @@ public extension Requestable {
 
         // encode url parameters
         if let urlParameters {
-            urlComponents.queryItems = urlParameters.map { URLQueryItem(name: $0, value: String(describing: $1)) }
+            urlComponents.queryItems = buildQueryItems(urlParameters: urlParameters)
         }
 
         return urlComponents
@@ -104,3 +104,39 @@ public extension Requestable {
         return request
     }
 }
+
+// MARK: Build Query Items
+private extension Requestable {
+    func buildQueryItems(urlParameters: [String: Any]) -> [URLQueryItem] {
+        urlParameters
+            .map { key, value -> [URLQueryItem] in
+                buildQueryItems(key: key, value: value)
+            }
+            .flatMap { $0 }
+    }
+
+    func buildQueryItems(key: String, value: Any) -> [URLQueryItem] {
+        if let arrayType = value as? ArrayParameter {
+            var queryItems: [URLQueryItem] = []
+
+            switch arrayType.arrayEncoding {
+            case .commaSeparated:
+                queryItems = [URLQueryItem(
+                    name: key,
+                    value: arrayType.values.map { String(describing: $0) }.joined(separator: ",")
+                )]
+
+            case .individual:
+                for parameter in arrayType.values {
+                    queryItems.append(URLQueryItem(
+                        name: key,
+                        value: String(describing: parameter)
+                    ))
+                }
+            }
+            return queryItems
+        }
+
+        return [URLQueryItem(name: key, value: String(describing: value))]
+    }
+}

Sources/Networking/Misc/ArrayEncoding.swift

@@ -0,0 +1,16 @@
+//
+//  ArrayEncoding.swift
+//  
+//
+//  Created by Dominika Gajdová on 08.05.2023.
+//
+
+import Foundation
+
+/// Associated array parameters query options.
+public enum ArrayEncoding {
+    /// filter=1,2,3
+    case commaSeparated
+    /// filter=1&filter=2&filter=3
+    case individual
+}

Sources/Networking/Misc/ArrayParameter.swift

@@ -0,0 +1,26 @@
+//
+//  File.swift
+//  
+//
+//  Created by Dominika Gajdová on 08.05.2023.
+//
+
+import Foundation
+
+/// Array parameter type for associated values with array encoding option.
+///
+/// The following example shows the use.
+///
+///     var urlParameters: [String: Any]? {
+///         ["filter": ArrayParameter([1, 2, 3], arrayEncoding: .individual)]
+///     }
+
+public struct ArrayParameter {
+    let values: [Any]
+    let arrayEncoding: ArrayEncoding
+
+    public init(_ values: [Any], arrayEncoding: ArrayEncoding = .individual) {
+        self.values = values
+        self.arrayEncoding = arrayEncoding
+    }
+}

Tests/NetworkingTests/AssociatedArrayQueryTests.swift

@@ -0,0 +1,64 @@
+//
+//  File.swift
+//  
+//
+//  Created by Dominika Gajdová on 08.05.2023.
+//
+
+@testable import Networking
+import XCTest
+
+final class AssociatedArrayQueryTests: XCTestCase {
+    enum TestRouter: Requestable {
+        case single
+        case arrayIndividual
+        case arraySeparated
+        case both
+
+        var baseURL: URL { URL(string: "http://someurl.com")! }
+        var path: String { "" }
+
+        var urlParameters: [String: Any]? {
+            switch self {
+            case .single:
+                return ["filter": 1]
+
+            case .arrayIndividual:
+                return ["filter": ArrayParameter([1, 2, 3], arrayEncoding: .individual)]
+
+            case .arraySeparated:
+                return ["filter": ArrayParameter([1, 2, 3], arrayEncoding: .commaSeparated)]
+
+            case .both:
+                return ["filter": ArrayParameter([1, 2, 3], arrayEncoding: .individual), "data": 5]
+            }
+        }
+    }
+
+    func testMultipleKeyParamaterURLCreation() async throws {
+        let urlRequest1 = try TestRouter.single.asRequest()
+        XCTAssertEqual("http://someurl.com/?filter=1", urlRequest1.url?.absoluteString ?? "")
+
+        let urlRequest2 = try TestRouter.arrayIndividual.asRequest()
+        XCTAssertEqual("http://someurl.com/?filter=1&filter=2&filter=3", urlRequest2.url?.absoluteString ?? "")
+
+        let urlRequest3 = try TestRouter.arraySeparated.asRequest()
+        XCTAssertEqual("http://someurl.com/?filter=1,2,3", urlRequest3.url?.absoluteString ?? "")
+
+        let urlRequest4 = try TestRouter.both.asRequest()
+
+        if let url = urlRequest4.url,
+           let components = URLComponents(url: url, resolvingAgainstBaseURL: true),
+           let queryItems = components.queryItems,
+           let parameters = TestRouter.both.urlParameters
+        {
+            let result = parameters.allSatisfy { (key, value) in
+                queryItems.contains(where: { $0.name == key })
+            }
+
+            XCTAssertTrue(result)
+        } else {
+            XCTFail("Invalid request url and/or query parameters.")
+        }
+    }
+}