Deserialize json.net property as uppercase

Question

Given the following POCO:

public class AggV2
{
    [JsonProperty("T")]
    public string Ticker { get; set; }
    [JsonProperty("v")]
    public decimal Volume { get; set; }
    [JsonProperty("o")]
    public decimal Open { get; set; }
    [JsonProperty("c")]
    public decimal Close { get; set; }
    [JsonProperty("h")]
    public decimal High { get; set; }
    [JsonProperty("l")]
    public decimal Low { get; set; }
    [JsonProperty("t")]
    [JsonConverter(typeof(UnixMillisecondsConverter))]
    public DateTimeOffset Timestamp { get; set; }
}

I have seen the 3rd party data provider is sending mixed case for the same ticker, i.e. MsFT and MSFT - the is causing nightmares with MSSQL key constraints!

First step is to filter to a common case, so that the Ticker property value would always be MSFT for the above example.

How can I ensure Ticker is always serialized as uppercase please?

Answer 1

I wrote the following converter, would this be the best practice way or have i reinvented the wheel?

public class AggV2
{
    [JsonProperty("T")]
    [JsonConverter(typeof(UppercaseStringConverter))]
    public string Ticker { get; set; }
    [JsonProperty("v")]
    public decimal Volume { get; set; }
    [JsonProperty("o")]
    public decimal Open { get; set; }
    [JsonProperty("c")]
    public decimal Close { get; set; }
    [JsonProperty("h")]
    public decimal High { get; set; }
    [JsonProperty("l")]
    public decimal Low { get; set; }
    [JsonProperty("t")]
    [JsonConverter(typeof(UnixMillisecondsConverter))]
    public DateTimeOffset Timestamp { get; set; }
    [JsonProperty("n")]
    public int Samples { get; set; }
}

public class UppercaseStringConverter : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        return objectType == typeof(string);
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        if (value is string str)
            writer.WriteValue(str.ToUpper());
        else
            throw new JsonSerializationException("Expected date object value.");
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        bool nullable = Nullable.GetUnderlyingType(objectType) != null;

        if (reader.TokenType == JsonToken.Null)
        {
            if (!nullable)
            {
                throw new JsonSerializationException($"Cannot convert null value to {objectType}.");
            }
            return null;
        }

        if (reader.TokenType == JsonToken.String)
            return ((string)reader.Value).ToUpper();
        else
            throw new JsonSerializationException($"Unexpected token parsing date. Expected String, got {reader.TokenType}.");
    }
}