fixed potential issue with multipart form

Author: pjechris

Sources/SimpleHTTP/Request/Request.swift

@@ -22,8 +22,6 @@ public struct Request<Output> {
     public let method: Method
     public let body: Body?
     public let query: [String: QueryParam]
-    /// content type to use for encoding the request body. If nil, the session default is used
-    public var contentType: HTTPContentType?
     public var cachePolicy: URLRequest.CachePolicy = .useProtocolCachePolicy
     public var headers: HTTPHeaderFields = [:]
 

Sources/SimpleHTTP/Session/Session.swift

@@ -71,9 +71,19 @@ 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 requestContentType = modifiedRequest.contentType ?? config.data.defaultType
+        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 = config.data.encoder[requestContentType] else {
+        guard let encoder else {
             throw SessionConfigurationError.missingEncoder(requestContentType)
         }
 

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
+    }
+}