public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
var jsonTypeHint = JsonTypeHintAttribute.For(value.GetType()).FirstOrDefault();
//JToken token;
//using (JTokenWriter jTokenWriter = new JTokenWriter())
//{
// serializer.Serialize(jTokenWriter, value);
// token = jTokenWriter.Token;
//}
//using (JTokenReader jTokenReader = new JTokenReader(token))
//{
// if (jsonTypeHint != null)
// {
// JObject jo = JObject.FromObject(value);
// jo.AddFirst(new JProperty(jsonTypeHint.Property, jsonTypeHint.Value));
// writer.WriteToken(jo.CreateReader());
// }
// else
// {
// writer.WriteToken(jTokenReader);
// }
//}
JObject jo = JObject.FromObject(value);
if (jsonTypeHint != null)
{
jo.AddFirst(new JProperty(jsonTypeHint.Property, jsonTypeHint.Value));
}
writer.WriteToken(jo.CreateReader());
}
/// <summary>
/// </summary>
/// <param name="baseType">The property type that is get or set (aka the assignable type).</param>
internal ConfigTypeJsonConverter(Type baseType) //, JsonSerializer innerSerializer)
{
Contract.Requires <ArgumentNullException>(baseType != null);
//Contract.Requires<ArgumentNullException>(innerSerializer != null);
//_innerSerializer = innerSerializer;
_baseType = baseType;
// Determine possible types
_possibleTypes = LogJamConfigTypes.GetConcreteTypesFor(baseType).ToArray();
// Create property name => types Lookup
_typesWithProperty = _possibleTypes.SelectMany(type => type.GetProperties().Select(property => new
{
type,
property
}))
.ToLookup(a => a.property.Name, a => a.type);
// Create TypeHint -> type lookup
_typesWithTypeHint = _possibleTypes.SelectMany(type => JsonTypeHintAttribute.For(type).Select(jsonHint => new
{
jsonHint,
type
}))
.ToLookup(a => a.jsonHint, a => a.type);
// Create list of TypeHint properties
_typeHintProperties = new HashSet <string>(_typesWithTypeHint.Select(grouping => grouping.Key.Property), StringComparer.OrdinalIgnoreCase);
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
if (!CanConvert(objectType))
{
throw new InvalidOperationException("Can't convert type " + objectType + "; expected " + _baseType);
}
// Load JObject from stream. Turns out we're also called for null arrays of our objects,
// so handle a null by returning one.
var jToken = JToken.Load(reader);
if (jToken.Type == JTokenType.Null)
{
return(null);
}
if (jToken.Type != JTokenType.Object)
{
throw new InvalidOperationException("Json: expected " + _baseType + "; got " + jToken.Type);
}
JObject jObject = (JObject)jToken;
// Narrow down the object type to 1, starting from all possible
HashSet <Type> remainingTypes = new HashSet <Type>(_possibleTypes);
foreach (var property in jObject)
{
if (remainingTypes.Count <= 1)
{
break;
}
// Check if it's a JsonTypeHint property
if (_typeHintProperties.Contains(property.Key) &&
(property.Value.Type == JTokenType.String))
{
var lookupTypeHint = new JsonTypeHintAttribute(property.Key, (string)property.Value);
var typesWithMatchingHint = _typesWithTypeHint[lookupTypeHint];
if (typesWithMatchingHint.Any())
{ // Narrow down based on the type hint
remainingTypes.IntersectWith(typesWithMatchingHint);
continue;
}
}
// Narrow down types to only those with this property
var typesWithProperty = _typesWithProperty[property.Key];
remainingTypes.IntersectWith(typesWithProperty);
}
if (remainingTypes.Count == 1)
{
// Found the only possible type
var target = Activator.CreateInstance(remainingTypes.First());
serializer.Populate(jObject.CreateReader(), target);
return(target);
}
else if (remainingTypes.Count == 0)
{
throw new JsonSerializationException(string.Format("No registered subclass of {0} contains all properties in JSON {1}", _baseType, jObject));
}
else
{
// Multiple types match: if a single type is inherited by all other candidate types, then that's the one we want (it's
// marked as serialisable and there's nothing to prompt us to deserialise as one of its subtypes instead). Otherwise,
// we have an ambiguity: there are two or more sibling types matching the same fields, and no clear (winning) supertype.
var commonBaseType = remainingTypes.SingleOrDefault(baseType => remainingTypes.All(childType => baseType.IsAssignableFrom(childType)));
if (commonBaseType != null)
{
var target = Activator.CreateInstance(commonBaseType);
serializer.Populate(jObject.CreateReader(), target);
return(target);
}
throw new JsonSerializationException(string.Format("Multiple subclasses of {0} contain all properties in JSON {1} : {2}",
_baseType,
jObject,
string.Join(", ", remainingTypes)));
}
}
private bool Equals(JsonTypeHintAttribute other)
{
return(other != null &&
string.Equals(Property, other.Property, StringComparison.OrdinalIgnoreCase) &&
string.Equals(Value, other.Value, StringComparison.OrdinalIgnoreCase));
}
