"Newtonsoft.Json.JsonSerializationException unable to find constructor to use for types" error when deserializing class

Question

I am developing an app in Xamarin Android. I have a splash screen where I serialize a class and pass it to MainActivity using Intent. When I try to deserialize it in MainActivity I get an error message :

"SerializationException unable to find constructor to use for types" 

Serialization :

void LoadData() {
    Currency currency = new Currency(this);
    intent = new Intent(this, typeof(MainActivity));
    intent.PutExtra("currency", Newtonsoft.Json.JsonConvert.SerializeObject(currency));
    StartActivity(intent);
}

Deserialization :

cur = Newtonsoft.Json.JsonConvert.DeserializeObject<Currency> (Intent.GetStringExtra("currency")); // I get the error here

Class constructor :

public Currency(Context context) {
    thiscontext = context;
}

I began experiencing this problem after I added the parameter Context context to the constructor. What has caused this? How can I solve it? Is it possible to serialize/deserialize class which has parameters?

Solution 1

You need to have an empty constructor in Currency class in order to deserialize it.

Solution 2

One other thing might cause this issue is if you have a full linking enabled in your android project. you need to preserve class and members using

[Runtime.Preserve(AllMembers = true)]
public class Currency
{}

Comments

[dampee]

Not really, you could have solutions like this: stackoverflow.com/a/28155770/97615

[Daniel]

you almost got it correct here... it was the linking type on the option => build iOS

[Emil]

@Daniel yes Ios has similar behavior. I wrote Android because question was for android. it can be applied for Ios as well

[Luke Alderton]

You're right, this issue seems to also be caused by the most recent Xamarin guidance to enable full linking to get around Xamarin.Forms using a deprecated API in the iOS app.