Casting Interfaces for Deserialization in JSON.Net

Casting interfaces for deserialization in JSON.NET

@SamualDavis provided a great solution in a related question, which I'll summarize here.

If you have to deserialize a JSON stream into a concrete class that has interface properties, you can include the concrete classes as parameters to a constructor for the class! The NewtonSoft deserializer is smart enough to figure out that it needs to use those concrete classes to deserialize the properties.

Here is an example:

public class Visit : IVisit
{
    /// <summary>
    /// This constructor is required for the JSON deserializer to be able
    /// to identify concrete classes to use when deserializing the interface properties.
    /// </summary>
    public Visit(MyLocation location, Guest guest)
    {
        Location = location;
        Guest = guest;
    }
    public long VisitId { get; set; }
    public ILocation Location { get;  set; }
    public DateTime VisitDate { get; set; }
    public IGuest Guest { get; set; }
}

Json deserialize a complex object with an Interface as a property

It turns out that I can change the property in the TaskDetail from IBehavior to dynamic and it works. Then when I need to use the concrete type I have a factory that can return a concrete type (i.e. torqueTool). At that point I can do

JsonConvert.DeserializeObject<TorqueTool>(taskDetail.Behavior.ToString());

Deserialization by JSON.NET of a list of interfaces inside another class

you must pass a "model" instead of "AggregatorItem" here:

// Root myDeserializedClass = JsonConvert.DeserializeObject<Root>(myJsonResponse); 
    public class Item
    {
        [JsonProperty("$type")]
        public string Type { get; set; }
        public bool IsPublished { get; set; }
        public int UId { get; set; }
        public int OwnerUId { get; set; }
        public string Name { get; set; }
        public int UIdStreet { get; set; }
        public int UIdArea { get; set; }
    }

    public class Root
    {
        [JsonProperty("$type")]
        public string Type { get; set; }
        public int UId { get; set; }
        public string Name { get; set; }
        public bool IsPublished { get; set; }
        public List<Item> Items { get; set; }
    }


 var lstAggregatorItem = JsonConvert.DeserializeObject<List<Root>>(tokenAggregators.ToString());

Deserialize collection of interface-instances?

Bellow full working example with what you want to do:

public interface ITestInterface
{
    string Guid { get; set; }
}

public class TestClassThatImplementsTestInterface1 : ITestInterface
{
    public string Guid { get; set; }
    public string Something1 { get; set; }
}

public class TestClassThatImplementsTestInterface2 : ITestInterface
{
    public string Guid { get; set; }
    public string Something2 { get; set; }
}

public class ClassToSerializeViaJson
{
    public ClassToSerializeViaJson()
    {
        this.CollectionToSerialize = new List<ITestInterface>();
    }
    public List<ITestInterface> CollectionToSerialize { get; set; }
}

public class TypeNameSerializationBinder : SerializationBinder
{
    public string TypeFormat { get; private set; }

    public TypeNameSerializationBinder(string typeFormat)
    {
        TypeFormat = typeFormat;
    }

    public override void BindToName(Type serializedType, out string assemblyName, out string typeName)
    {
        assemblyName = null;
        typeName = serializedType.Name;
    }

    public override Type BindToType(string assemblyName, string typeName)
    {
        var resolvedTypeName = string.Format(TypeFormat, typeName);
        return Type.GetType(resolvedTypeName, true);
    }
}

class Program
{
    static void Main()
    {
        var binder = new TypeNameSerializationBinder("ConsoleApplication.{0}, ConsoleApplication");
        var toserialize = new ClassToSerializeViaJson();

        toserialize.CollectionToSerialize.Add(
            new TestClassThatImplementsTestInterface1()
            {
                Guid = Guid.NewGuid().ToString(), Something1 = "Some1"
            });
        toserialize.CollectionToSerialize.Add(
            new TestClassThatImplementsTestInterface2()
            {
                Guid = Guid.NewGuid().ToString(), Something2 = "Some2"
            });

        string json = JsonConvert.SerializeObject(toserialize, Formatting.Indented, 
            new JsonSerializerSettings
            {
                TypeNameHandling = TypeNameHandling.Auto,
                Binder = binder
            });
        var obj = JsonConvert.DeserializeObject<ClassToSerializeViaJson>(json, 
            new JsonSerializerSettings
            {
                TypeNameHandling = TypeNameHandling.Auto,
                Binder = binder 
            });

        Console.ReadLine();
    }
}