c# – JSON.NET,如果预期的对象无法反序列化,则实例化回退对象

用JsonConverter修饰的节点基类

[JsonObject( IsReference = true,TypeNameHandling = TypeNameHandling.All )]
[JsonConverter( typeof( ChainNodeConverter ))]
public abstract class Node
{
    public List< Node > Children { get; set; }
}

ErrorNode类具有一些属性来帮助id /恢复失败的节点

public class ErrorNode : Node
{
    public JToken JToken { get; set; }
    public string FailedTypeString { get; set; }
}

NodeConverer类

public class NodeConverter : JsonConverter
{
    public override bool CanRead { get { return true; } }

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

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


    public override void WriteJson( JsonWriter writer,object value,JsonSerializer serializer )
    {
        throw new NotImplementedException("If CanWrite is false; this won't be called.");
    }


    public override object ReadJson( JsonReader reader,Type objectType,object existingValue,JsonSerializer serializer )
    {
        var jToken = JToken.ReadFrom( reader );

        var refString = jToken.Value< string >( "$ref" );
        var firstReference = refString == null;

        if ( firstReference )
        {
            var typeString = jToken.Value<string>( "$type" );

            if ( typeString != null )
            {
                var type = Type.GetType( typeString );

                if ( type == null )
                {
                    var errorNode = new ErrorNode();

                    errorNode.JToken = jToken;
                    errorNode.FailedTypeString = typeString;

                    // Apply the old node's relationships to errorNode
                    serializer.Populate( jToken.CreateReader(),errorNode );

                    return errorNode;
                }
            }
        }

        // Default-like behaviour
        return serializer.Deserialize( jToken.CreateReader() );
    }
}