How to Call JSONconvert.Deserializeobject and Disable a JSONconverter Applied to a Base Type via [JSONconverter]

How to call JsonConvert.DeserializeObject and disable a JsonConverter applied to a base type via [JsonConverter]?

Since you have added [JsonConverter(typeof(JsonProductConverted))] directly to your Product type, you could add a dummy converter to ProductImpl that returns false from CanRead and CanWrite:

[JsonConverter(typeof(NoConverter))]
public class ProductImpl : Product
{
}

public class NoConverter : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        return false;
    }

    public override bool CanRead { get { return false; } }

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

    public override bool CanWrite { get { return false; } }

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

This overrides the base class's converter and then falls back on default serialization for both reading and writing

Sample .Net fiddle.

Another option would be to use serializer.Populate(). This avoids the call to the converter for the object itself:

public class JsonProductConverted : JsonTypeInferringConverterBase
{
    protected override Type InferType(Type objectType, JObject json)
    {
        //var type = GetTypeFromId((int) json["typeId"]); // Construct type from field in 
        return typeof(ProductImpl);
    }

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

public abstract class JsonTypeInferringConverterBase : JsonConverter
{
    public override bool CanWrite { get { return false; } }

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

    protected abstract Type InferType(Type objectType, JObject json);

    protected virtual object CreateObject(Type actualType, JsonSerializer serializer, JObject json)
    {
        var contract = (JsonObjectContract)serializer.ContractResolver.ResolveContract(actualType);
        return contract.DefaultCreator();
    }

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

        var actualType = InferType(objectType, json);

        // Construct object (or reuse existingValue if compatible)
        if (existingValue == null || !actualType.IsAssignableFrom(existingValue.GetType()))
        {
            existingValue = CreateObject(actualType, serializer, json);
        }

        // Populate object.
        using (var subReader = json.CreateReader())
        {
            serializer.Populate(subReader, existingValue);
        }

        return existingValue;
    }
}

Note that the concrete objects must have parameterless constructors for this to work. If not, you can override protected virtual object CreateObject(Type actualType, JsonSerializer serializer, JObject json) and manually invoke a parameterized constructor by deserializing select properties inside the JObject json.

Sample fiddle #2.

How to ignore base class JsonConverter when deserializing derived classes?

Did you try to remove the [JsonConvert]-attribute from your base class? In my example I invoke my "custom" converter manually:
https://github.com/Code-Inside/Samples/blob/b635580a4966b1b77c93a8b682389c6cf06d2da6/2015/JsonConvertIssuesWithBaseClasses/JsonConvertIssuesWithBaseClasses/Program.cs#L36-L79

How to implement custom JsonConverter in JSON.NET?

Using the standard CustomCreationConverter, I was struggling to work how to generate the correct type (Person or Employee), because in order to determine this you need to analyse the JSON and there is no built in way to do this using the Create method.

I found a discussion thread pertaining to type conversion and it turned out to provide the answer. Here is a link: Type converting (archived link).

What's required is to subclass JsonConverter, overriding the ReadJson method and creating a new abstract Create method which accepts a JObject.

The JObject class provides a means to load a JSON object and
provides access to the data within this object.

The overridden ReadJson method creates a JObject and invokes the Create method (implemented by our derived converter class), passing in the JObject instance.

This JObject instance can then be analysed to determine the correct type by checking existence of certain fields.

Example

string json = "[{
        \"Department\": \"Department1\",
        \"JobTitle\": \"JobTitle1\",
        \"FirstName\": \"FirstName1\",
        \"LastName\": \"LastName1\"
    },{
        \"Department\": \"Department2\",
        \"JobTitle\": \"JobTitle2\",
        \"FirstName\": \"FirstName2\",
        \"LastName\": \"LastName2\"
    },
        {\"Skill\": \"Painter\",
        \"FirstName\": \"FirstName3\",
        \"LastName\": \"LastName3\"
    }]";

List<Person> persons = 
    JsonConvert.DeserializeObject<List<Person>>(json, new PersonConverter());

...

public class PersonConverter : JsonCreationConverter<Person>
{
    protected override Person Create(Type objectType, JObject jObject)
    {
        if (FieldExists("Skill", jObject))
        {
            return new Artist();
        }
        else if (FieldExists("Department", jObject))
        {
            return new Employee();
        }
        else
        {
            return new Person();
        }
    }

    private bool FieldExists(string fieldName, JObject jObject)
    {
        return jObject[fieldName] != null;
    }
}

public abstract class JsonCreationConverter<T> : JsonConverter
{
    /// <summary>
    /// Create an instance of objectType, based properties in the JSON object
    /// </summary>
    /// <param name="objectType">type of object expected</param>
    /// <param name="jObject">
    /// contents of JSON object that will be deserialized
    /// </param>
    /// <returns></returns>
    protected abstract T Create(Type objectType, JObject jObject);

    public override bool CanConvert(Type objectType)
    {
        return typeof(T).IsAssignableFrom(objectType);
    }

    public override bool CanWrite
    {
        get { return false; }
    }

    public override object ReadJson(JsonReader reader, 
                                    Type objectType, 
                                     object existingValue, 
                                     JsonSerializer serializer)
    {
        // Load JObject from stream
        JObject jObject = JObject.Load(reader);

        // Create target object based on JObject
        T target = Create(objectType, jObject);

        // Populate the object properties
        serializer.Populate(jObject.CreateReader(), target);

        return target;
    }
}

---

Related Topics