CODEWITHSUNDEEP
c#json.net
Keith Nicholas
Keith Nicholas

Reputation: 44288

How to fake the type in JSON.NET when serializing out?

lets say I have

public class Person
    {
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public string PhoneNumber { get; set; }
    }

now, if I create an anonymous type like...

var p = new Person() {FirstName = "bob",
                      LastName = "builder",
                      PhoneNumber = "0800 YESWECAN"};

var anon = new {p.FirstName, p.LastName};

with JSON.NET, when you have TypeNameHandling = TypeNameHandling.Objects, it will serialize ( and then use for deserilization ) the type. What I'm wanting to do, is to fake the type in the annoymous class so that when it gets serialized it looks like a "Person" object.

Is there a nice simple way to do this?

NOTE: It MUST have the Json.Net type information in the json ( $type ). So LBs answer doesn't solve the problem, in fact I could just use the .net frameworks json facilities to do exactly that.

Upvotes: 3

Views: 3629

Answers (2)

Keith Nicholas
Keith Nicholas

Reputation: 44288

to fake it, I can introduce a contract to change a property name when outputting the json... eg...

 public class FakeTypeContractResolver : DefaultContractResolver
    {        
        protected override string ResolvePropertyName(string propertyName)
        {
            return propertyName == "_type_" ? "$type" : propertyName;
        }
    }

so if you have json.net deserializer settings set to 

TypeNameHandling = TypeNameHandling.Objects
TypeNameAssemblyFormat = FormatterAssemblyStyle.Full

you can make an annoymous type like the following,

var x = new 
{
     _type_ = typeof(Person).AssemblyQualifiedName,
     p.FirstName, 
     p.LastName
}

Which will pretend to be a "Person" in the type information, meaning if you deserialize it you will get a person object.

NOTE: the serializer to json settings must be set not to serialize out type information when you are faking it.

Upvotes: 2

L.B
L.B

Reputation: 116098

You can serialize as

string str = JsonConvert.SerializeObject(new { FirstName = "aaa", LastName = "bbb" })

and you will get a string which looks like Person object

{"FirstName":"aaa","LastName":"bbb"}

Since Json doesn't contain type informations you can deserialize it back to Person

var person = JsonConvert.DeserializeObject(str, typeof(Person));

Upvotes: 3

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