RxAlamofire - how to get the response on error?

Question

I need the response body when an error occurs in an RxAlamofire call. I've seen this hack but I wonder if there's a cleaner way.

Inspired by it, I created this RxAlamofire fork with a similar hack. With it, errors will usually be an instance of DataResponseError so you can do this:

RxAlamofire.data(method, url).subscribe(

  onError: { error in

    if let error = error as? DataResponseError<Data> {

      // Get response body (in this case, convert it to a String)
      if let data = error.response.data {
          let message = String(data: data, encoding: String.Encoding.utf8)
          print("Message: \(message)")
      }

      // Get status code
      if let statusCode = error.response.response?.statusCode {
          print("Status code: \(statusCode)")
      }
    }
  }
)

score 2 · Answer 1 · answered May 01 '18 at 12:35

Issue description. I'm using RxAlamofire to make network requests, and I needed to get information from the body of the error response.

I've made a hack in a folloing way:

Added a PError:

import UIKit
import Alamofire
import ObjectMapper

class PError: Error, Mappable {
    var message: String?
    var statusCode: Int?

    required init?(map: Map) {

    }

    func mapping( map: Map) {
        message <- map["error.message"]
        statusCode <- map["error.statusCode"]
    }
}

And now added such extensions to DataRequest:

import Alamofire
import ObjectMapper

    extension DataRequest {
        //Overriding several methods from Alamofire Validation
        @discardableResult
        public func validate<S: Sequence>(statusCode acceptableStatusCodes: S) -> Self where S.Iterator.Element == Int {
            return validate { [unowned self] _, response, bodyData in
                return self.validate(statusCode: acceptableStatusCodes, response: response, bodyData: bodyData)
            }
        }

        //Overriding several methods from Alamofire Validataion
        fileprivate func validate<S: Sequence>(
            statusCode acceptableStatusCodes: S,
            response: HTTPURLResponse, bodyData: Data?)
            -> ValidationResult
            where S.Iterator.Element == Int
        {
            if acceptableStatusCodes.contains(response.statusCode) {
                return .success
            } else {
                var error: Error = AFError.responseValidationFailed(reason: AFError.ResponseValidationFailureReason.unacceptableStatusCode(code: response.statusCode))
                if let bodyData = bodyData {
                    if let jsonString = String(data: bodyData, encoding: .utf8) {
                        if let errorNew = Mapper<PError>().map(JSONString: jsonString)
                        {
                            error = errorNew
                        }
                    }
                }
                return .failure(error)
            }
        }
    }

Next, somewhere in the code you'll be able to work with this custom error object:

if let err = error as? PError {
                status = err.message ?? "No message in the error description"
            }
            else

RxAlamofire - how to get the response on error?

1 Answers1