Can't call Web Api by Alamofire.upload multipartFormData

Question

I have an Windows WEB API with the following method:

public async Task<IHttpActionResult> SaveContract([FromBody] ModelDTO model)
{
  string custName = model.CustomerName;
  ...
}

The Model I want looks like this:

public class ModelDTO
    {      
        public int CustomerNumber { set; get; }        
        public string CustomerName { set; get; }
        public string CustomerMail { set; get; }        
        public string imageDataBase64 { set; get; }
    }      

I want to call the API with my iOS App (Swift 4) with Alamofire 4.7.2 My dev server has a self-signed certificate. So I need to disable the evaluation.

let defaultManager: Alamofire.SessionManager = {
        let serverTrustPolicies: [String: ServerTrustPolicy] = [
            "devserver": .disableEvaluation           
        ]

        let configuration = URLSessionConfiguration.default
        configuration.httpAdditionalHeaders =   Alamofire.SessionManager.defaultHTTPHeaders

        return Alamofire.SessionManager(
            configuration: configuration,
            serverTrustPolicyManager: ServerTrustPolicyManager(policies: serverTrustPolicies))
    }()


let webApi: String = "https://devserver:7208/api/KP/SaveContract"

let data = UIImageJPEGRepresentation(photoImageView.image!,1) //got the Data form an image view

var imgString: String = ""

imgString = data.base64EncodedString()

let Param =  Parameters = [
                "CustomerNumber": 1,               
                "CustomerName": "Test Name",
                "CustomerMail": "test@test.com",                
                "imageDataBase64": imgString]

defaultManager.upload(
        multipartFormData: { multipartFormData in
            for (key, value) in contAsJsonParam {
            multipartFormData.append("\(value)".data(using: .utf8)!, withName:key)
            }            
        },
        to: webApi,
        encodingCompletion: { encodingResult in
                        switch encodingResult {
                            case .success(let upload, _, _):
                                    upload.responseJSON { response in
                                    debugPrint(response)
                                        //lbl sichtbar machen
                                    }
                            case .failure(let encodingError):
                            print(encodingError)
                            }
            })

Call the api without image with Alamofire.request works, but with image request, it dosen't work. (bad ssl error) So I try the upload method, but upload dosen't work in any way (with or without image string)

If I call the Api with Alamofire.upload I got a system.net.http.unsupportedmediatypeexception

"No MediaTypeFormatter is available to read an object of type 'ModelDTO' from content with media type 'multipart/form-data'."

I try to make the upload class as json by at "headers: Content-Type:application/json" but no effect.

I try to fix it by putting

config.Formatters.JsonFormatter.SupportedMediaTypes.Add(new MediaTypeHeaderValue("multipart/form-data"));

in the WebApiConfig. Then i got an other error I got an NullReferenceException in the api at the line "string custName = model.CustomerName;"

Answer 1

You can use this code. I have tested this code with multipart data. It's working fine for me.

    let url = "https://devserver:7208/api/KP/SaveContract"
        //imp data need to be dynamic

        let parameters: NSMutableDictionary = ["userId":"1123",
                                               "caption":"hello how are you",
                                               "keyword":"First Post",
                                               "askPrice":"12345",
                                               "postScope":"1",
                                               "commentStatus":"1",
                                               "gender":"male",
                                               "email":"asd@asd.com"
                                              ]

        var dictionaryHeaders = [String : String]()
        dictionaryHeaders = ["Content-Type": "application/x-www-form-urlencoded" ]


        Alamofire.upload(multipartFormData: { (multipartFormData) in
            for (key, value) in parameters {
                multipartFormData.append("\(value)".data(using: String.Encoding.utf8)!, withName: key as! String)
            }


            self.postImage = UIImage(named:"YOUR IMAGE NAME")


                if let data = UIImageJPEGRepresentation(self.postImage,1) {
                    multipartFormData.append(data, withName: "postPic", fileName: "image.png", mimeType: "image/png")
                }



        }, usingThreshold: UInt64.init(), to: url, method: .post, headers: dictionaryHeaders ) { (result) in
            switch result{
            case .success(let upload, _, _):
                upload.responseJSON{ response in

                    print(response)
                }
            case .failure(let error):
                print("Error in upload: \(error.localizedDescription)")
            }
        }