So I have two classes like the ones below. They are both in the same namespace and in the same shared project.
public class Person{
public string Name{get;set;}
}
public class EmployedPerson : Person{
public string JobTitle{get;set;}
}
When I serilize these items into rabbitmq I am serializing as the base class like so:
JsonSerializerSettings settings = new JsonSerializerSettings
{
TypeNameAssemblyFormatHandling = TypeNameAssemblyFormatHandling.Simple,
TypeNameHandling = TypeNameHandling.Objects
};
JsonConvert.SerializeObject(input, settings)
However when deserializing I run into issues. I would like to be able to do something like shown below where I deserialize as the base class and then check if it is a inheirited type.
Type check:
Person person = Deserialize<Person>(e.Body, Encoding.Unicode);
if (person is EmployedPerson)
{
logger.LogInformation("This person has a job!");
}
Deserialize settings:
JsonSerializerSettings settings = new JsonSerializerSettings
{
TypeNameAssemblyFormatHandling = TypeNameAssemblyFormatHandling.Simple,
TypeNameHandling = TypeNameHandling.Auto
};
Deserialize logic:
private static T Deserialize<T>(byte[] data, Encoding encoding) where T : class
{
try
{
using (MemoryStream stream = new MemoryStream(data))
using (StreamReader reader = new StreamReader(stream, encoding))
return JsonSerializer.Create(settings).Deserialize(reader, typeof(T)) as T;
}
catch (Exception e)
{
Type typeParameter = typeof(T);
logger.LogError(LogEvent.SERIALIZATION_ERROR, e, "Deserializing type {@TypeName} failed", typeParameter.Name);
logger.LogInformation(Encoding.UTF8.GetString(data));
return default(T);
}
}
Result: The above code fails because the $type property contains the Assembly name and on each end of rabbitmq the assembly name is different because the classes are inside a shared project.
Example error:
Newtonsoft.Json.JsonSerializationException: Error resolving type specified in JSON 'Shared.Objects.EmployedPerson, Person.Dispatcher'. Path '$type', line 1, position 75. ---> System.IO.FileNotFoundException: Could not load file or assembly 'Person.Dispatcher, Culture=neutral, PublicKeyToken=null'. The system cannot find the file specified.
Thank you @dbc, your suggestion to write a custom SerializationBinder is, as far as I can tell, the best solution to my problem.
I used the KnownTypesBinder as implemented at: https://www.newtonsoft.com/json/help/html/SerializeSerializationBinder.htm
KnownTypesBinder:
JsonSerializerSettings with the SerializationBinder set to an instance of KnownTypesBinder was used on both the serializing and deserializing endpoints. I probably only need it for the deserializing end, but put it in both for consistency.
After creating a settings object then I pass it into the JsonConvert serialization functions.
Also note that KnownTypes in KnownTypesBinder must be prepopulated with all of the non primitive types you will be deserializing.
Edit: I am currently not accepting my own answer because I have no idea how to handle List of complex types. For instance if a Person has a List and a List, what type do you return when the typeName is "List`1" and it could be either one.
Edit The following version of the KnownTypesBinder solved my issues related to Lists of objects.