C#•2y ago

❔ Using JsonConvert to send over interface

Hello everyone, after long times of googling I sadly haven't found any solution to a jsonconvert problem with interfaces. I have three projects: Client, Server, Shared. Both Client and Server can access Shared. In the shared project I have the following classes: S_Mode1:S_IMode, S_Mode2:S_IMode which inherit from the interface S_IMode Now my goal is to serialize these classes using JsonConvert and send them from the server to the client. My idea is to send them as an S_IMode so that on the client I can use them as expected and still differentiate between S_Mode1 and S_Mode1 I am currently serializing this into a string from the server using

string jsonNewMode = JsonConvert.SerializeObject(mode.AsSharedMode, new JsonSerializerSettings() { TypeNameHandling = TypeNameHandling.Auto });
//mode.AsSharedMode returns either S_Mode1 or S_Mode2 casted into an S_IMode

string jsonNewMode = JsonConvert.SerializeObject(mode.AsSharedMode, new JsonSerializerSettings() { TypeNameHandling = TypeNameHandling.Auto });
//mode.AsSharedMode returns either S_Mode1 or S_Mode2 casted into an S_IMode

and then trying to deserialize

S_IMode s1 = JsonConvert.DeserializeObject<S_IMode>(value, new JsonSerializerSettings() { TypeNameHandling = TypeNameHandling.Auto });

S_IMode s1 = JsonConvert.DeserializeObject<S_IMode>(value, new JsonSerializerSettings() { TypeNameHandling = TypeNameHandling.Auto });

Sadly this fails with

Newtonsoft.Json.JsonSerializationException: Could not create an instance of type GCShared.NewModus.Networking.S_IMode. Type is an interface or abstract class and cannot be instantiated. Path 'Id', line 1, position 6.

Any tips what I can do?

5 Replies

Kouhai•2y ago

As the error suggests, you can't create new instances of interfaces or abstract classes Why do you want to deserialize as an interface?

KeyinatorOP•2y ago

This is code for a gameserver which has multiple modes. Depending on the mode the player is in it functions will perform differently. I have a Property current_mode which is used for all of that. Now depending on the underlying class that current_mode is, the functions will perform differently. So now to put that information from the server to the client, I wanted to send it via the method above.

Kouhai•2y ago

Okay, best option would be to send a flag that determines the mode before the deserialization

JakenVeina•2y ago

a better solution is to properly model your data

Depending on the mode the player is in it functions will perform differently.

data shouldn't be performing functions, data should be data if your data can vary depending on what mode the server is running in, and you need interfaces to handle that, you haven't properly modeled your data

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ Using JsonConvert to send over interface