Parsing JSON into C# Object - Get Properties Dynamically

You have several issues here:

• Your root object has a large, variable number of properties whose values correspond to a fixed data type PoloniexPairInfo. Since you don't want to create a root type that hardcodes all these properties, you can deserialize to a Dictionary<string, PoloniexPairInfo> as shown in Create a strongly typed c# object from json object with ID as the name.

• The Bid and Ask properties are represented in JSON as an array of arrays of values of different types:

  [
    [
      "0.00007359",
      163.59313969
    ]
  ]
  

  You would like to map the inner arrays to a fixed POCO PoloniexPriceVolume by binding values at specific array indices to specific c# properties. You can do this using ObjectToArrayConverter<PoloniexPriceVolume> from C# JSON.NET - Deserialize response that uses an unusual data structure.

• Finally, the JSON value "isFrozen" has a string value "0" but you would like to map it to a bool value public bool IsFrozen { get; set; }. You can do this by adapting BoolConverter from Convert an int to bool with Json.Net.

Putting all this together, your can deserialize your JSON with the following models and converters:

[JsonConverter(typeof(ObjectToArrayConverter<PoloniexPriceVolume>))]
public class PoloniexPriceVolume
{
    [JsonProperty(Order = 1)]
    public string Price { get; set; }
    [JsonProperty(Order = 2)]
    public double Volume { get; set; }
}

public class PoloniexPairInfo
{
    public List<PoloniexPriceVolume> Asks { get; set; }
    public List<PoloniexPriceVolume> Bids { get; set; }
    [JsonConverter(typeof(BoolConverter))]
    public bool IsFrozen { get; set; }
    public int Seq { get; set; }
}

public class ObjectToArrayConverter<T> : JsonConverter
{
    //https://stackoverflow.com/a/39462464/3744182
    public override bool CanConvert(Type objectType)
    {
        return typeof(T) == objectType;
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        var objectType = value.GetType();
        var contract = serializer.ContractResolver.ResolveContract(objectType) as JsonObjectContract;
        if (contract == null)
            throw new JsonSerializationException(string.Format("invalid type {0}.", objectType.FullName));
        writer.WriteStartArray();
        foreach (var property in SerializableProperties(contract))
        {
            var propertyValue = property.ValueProvider.GetValue(value);
            if (property.Converter != null && property.Converter.CanWrite)
                property.Converter.WriteJson(writer, propertyValue, serializer);
            else
                serializer.Serialize(writer, propertyValue);
        }
        writer.WriteEndArray();
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        var contract = serializer.ContractResolver.ResolveContract(objectType) as JsonObjectContract;
        if (contract == null)
            throw new JsonSerializationException(string.Format("invalid type {0}.", objectType.FullName));

        if (reader.MoveToContentAndAssert().TokenType == JsonToken.Null)
            return null;
        if (reader.TokenType != JsonToken.StartArray)
            throw new JsonSerializationException(string.Format("token {0} was not JsonToken.StartArray", reader.TokenType));

        // Not implemented: JsonObjectContract.CreatorParameters, serialization callbacks, 
        existingValue = existingValue ?? contract.DefaultCreator();

        using (var enumerator = SerializableProperties(contract).GetEnumerator())
        {
            while (true)
            {
                switch (reader.ReadToContentAndAssert().TokenType)
                {
                    case JsonToken.EndArray:
                        return existingValue;

                    default:
                        if (!enumerator.MoveNext())
                        {
                            reader.Skip();
                            break;
                        }
                        var property = enumerator.Current;
                        object propertyValue;
                        // TODO:
                        // https://www.newtonsoft.com/json/help/html/Properties_T_Newtonsoft_Json_Serialization_JsonProperty.htm
                        // JsonProperty.ItemConverter, ItemIsReference, ItemReferenceLoopHandling, ItemTypeNameHandling, DefaultValue, DefaultValueHandling, ReferenceLoopHandling, Required, TypeNameHandling, ...
                        if (property.Converter != null && property.Converter.CanRead)
                            propertyValue = property.Converter.ReadJson(reader, property.PropertyType, property.ValueProvider.GetValue(existingValue), serializer);
                        else
                            propertyValue = serializer.Deserialize(reader, property.PropertyType);
                        property.ValueProvider.SetValue(existingValue, propertyValue);
                        break;
                }
            }
        }
    }

    static IEnumerable<JsonProperty> SerializableProperties(JsonObjectContract contract)
    {
        return contract.Properties.Where(p => !p.Ignored && p.Readable && p.Writable);
    }
}

public static partial class JsonExtensions
{
    //https://stackoverflow.com/a/39462464/3744182
    public static JsonReader ReadToContentAndAssert(this JsonReader reader)
    {
        return reader.ReadAndAssert().MoveToContentAndAssert();
    }

    public static JsonReader MoveToContentAndAssert(this JsonReader reader)
    {
        if (reader == null)
            throw new ArgumentNullException();
        if (reader.TokenType == JsonToken.None)       // Skip past beginning of stream.
            reader.ReadAndAssert();
        while (reader.TokenType == JsonToken.Comment) // Skip past comments.
            reader.ReadAndAssert();
        return reader;
    }

    public static JsonReader ReadAndAssert(this JsonReader reader)
    {
        if (reader == null)
            throw new ArgumentNullException();
        if (!reader.Read())
            throw new JsonReaderException("Unexpected end of JSON stream.");
        return reader;
    }
}

public class BoolConverter : JsonConverter
{
    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        writer.WriteValue(((bool)value) ? "1" : "0");
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        if (reader.TokenType == JsonToken.Null)
            return null;

        var token = JToken.Load(reader);

        if (token.Type == JTokenType.Boolean)
            return (bool)token;
        return token.ToString() != "0";
    }

    public override bool CanConvert(Type objectType)
    {
        return objectType == typeof(bool);
    }
}

And finally, do:

var orderBook = JsonConvert.DeserializeObject<Dictionary<string, PoloniexPairInfo>>(jsonString);

Working .Net fiddle.