Json deserialization, unable to parse int into string when deserializing. Tried to fix this issue with a custom converter class

Question

I receive an int from rest API I want json deserializer to put into string property "Hovednummer", but I receive an error saying can't convert from int to string.

I tried to fix this with a custom converter class I call IntToStringConverter. And I add a Json property to the property Hovednummer [JsonConverter(typeof(IntToStringConverter))].

But it doesn't work, when I debug the program it doesn't even enter any breakpoint in the custom converter class.

namespace CrownData.DataInteractionLayer.DanishCrown.Models
{
    public class StemDataReadDTO
    {
        [JsonConverter(typeof(IntToStringConverter))]
        public string Hovednummer { get; set; }
        public EjerStem Ejer { get; set; }
    }


    public class IntToStringConverter : Newtonsoft.Json.JsonConverter
    {
        public override bool CanConvert(Type typeToConvert)
        {
            return typeToConvert == typeof(string);
        }

        public override bool Equals(object obj)
        {
            return base.Equals(obj);
        }

        public override int GetHashCode()
        {
            return base.GetHashCode();
        }

        public object IntToString(JsonReader reader) //, Type objectType, object existingValue, JsonSerializer serializer
        {
            if (reader.TokenType == JsonToken.Null)
                return null;
            if (reader.TokenType == JsonToken.String)
                return reader.Value;
            if (reader.TokenType == JsonToken.Integer)
                return reader.Value.ToString();

            throw new JsonReaderException(string.Format("Unexcepted token {0}", reader.TokenType));
        }

        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
        {
            throw new NotImplementedException();
        }

        public override string ToString()
        {
            return base.ToString();
        }

        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
        {
            throw new NotImplementedException();
        }
    }

• TryGetStemData, getting data. This works, I get something. I just want the hovedenr datatype to stay string. Right now I'm forced to set it as int.

    public bool TryGetStemData(string hovedNummer, string cvrNummer, out Models.StemDataReadDTO stemData)
    {
        string url = _dcConfig.UrlStemData;
        StemDataCreateDTO payload = new()
        {
            CVRnr = cvrNummer,
            Hovednr = hovedNummer
        };
        var stemTask = GetClientDataAsPostAsync<Models.StemDataReadDTO>(url, payload);
        stemTask.Wait();
        stemData = stemTask.Result.result;
        return stemTask.Result.succes;
    }
  

• GetClientDataAsPostAsync method, it's a generic method used for getting and validate reponses.

    private async Task<(bool succes, T result)> GetClientDataAsPostAsync<T>(string url, object payload, bool allowNull = false)
    {
        bool isValid = false;
        int MaxTimeout = 20;
        var cts = new CancellationTokenSource(TimeSpan.FromSeconds(MaxTimeout));
        T result = default;
        try
        {
            HttpResponseMessage response = await _client.PostAsJsonAsync(url, payload, _serializerOptions, cts.Token);
  
            if (response.IsSuccessStatusCode)
            {
                result = await JsonSerializer.DeserializeAsync<T>(await response.Content.ReadAsStreamAsync());
                if (result == null && !allowNull)
                {
                    ErrorMessage = "Ugyldigt returdata";
                }
                else
                {
                    isValid = true;
                }
  
            }
            else
            {
                ErrorMessage = (await response.Content.ReadAsStringAsync()) ?? response.ReasonPhrase;
            }
        }
        catch (TaskCanceledException e)
        {
            ErrorMessage = $"Timout: {e.Message}";
        }
        catch (Exception e)
        {
            ErrorMessage = e.Message;
        }
        return (isValid, result);
    }
  

• I setting some options here, but I get the same error even with the numberHandling set to Write as string.

        _serializerOptions = new JsonSerializerOptions()
        {
            PropertyNamingPolicy = null,
            NumberHandling = (System.Text.Json.Serialization.JsonNumberHandling.WriteAsString),
        };