How I can fetch codingPath when codable issue happens?

Question

I tried this, but it raise an error:

do {
            guard let firstValue = result.values.first else {
                completion?(nil, NSError(domain: "MyDomain", code: 1, userInfo: [NSLocalizedDescriptionKey: "No first value found"]))
                return
            }
            let jsonData = try JSONSerialization.data(withJSONObject: firstValue, options: [])
            let jsonStr = String(data: jsonData, encoding: .utf8)
            //print(jsonStr!)
            let decoder = JSONDecoder()
            let decodedObject = try decoder.decode(T.self, from: jsonData)
            completion?(decodedObject, nil)
        } catch let decodingError as DecodingError {
            print("Failed to decode JSON: \(decodingError)")
            if let context = decodingError.context { // <----- HERE
                print("Coding path: \(context.codingPath)")
            }
        } catch let error {
            print("An error occurred: \(error)")
            // handle the error here
        }

Type of expression is ambiguous without more context

Answer 1

Expanding on Joakim post if you would like to use the syntax at your post you can extend DecodingError enum as follow:

extension DecodingError {

    var context: Context {
        let context: Context
        switch self {
        case let .dataCorrupted(ctxt):
            context = ctxt
        case let .keyNotFound(_, ctxt):
            context = ctxt
        case let .typeMismatch(_, ctxt):
            context = ctxt
        case let .valueNotFound(_, ctxt):
            context = ctxt
        @unknown default:
            fatalError()
        }
        return context
    }

    var codingPath: [CodingKey] {
       context.codingPath
    }

    var underlyingError: Error? {
        context.underlyingError
    }
}