I'm using a very strange api, it's data field type is dynamic.
If error occured, the data field will be a string like this:
{
"code": 2001,
"data": "Error!"
}
And if success, the data field will be a object:
{
"code": 2000,
"data": {
"id": 1,
"name": "example"
}
}
I'm using the following Kotlin code to de-serialize it:
return Gson().fromJson(data, SimpleModel::class.java)
The model definition is down below:
import com.google.gson.annotations.SerializedName
class SimpleModel {
@SerializedName("code")
val code = 0
@SerializedName("data")
val data: SimpleData = SimpleData()
}
class SimpleData {
@SerializedName("id")
val id = ""
@SerializedName("name")
val name = ""
}
When no error occred, the code above works just fine. However when error occured, exception was thrown:
java.lang.IllegalStateException: Excepted BEGIN_OBJECT but was STRING at line 1 column x $path.data
Is there a way to de-serialize data field to an object or just anything and determine it's type by code manually?
You would need to write a custom deserializer, which decides what type to deserialize data into, depending on the runtime type of the node, and register that deserializer with your Gson instance. Unfortunately i am not familiar with kotlin syntax, so i can only give you pseudo code.
data in SimpleModel should be either Object, or make the class generic - SimpleModel<T>, and the field should be of type T as well.JsonElement.JsonElement root = parseResponse();
root.getAsJsonObject().get("data").getAsString();
getAs...() methods to check type.SimpleModel.getAsJsonObject(), parse the object to SimpleData and set this new object in SimpleModel.You could use my my answer here as inspiration. Although it's about object mapper, it does the same thing - decides object type depending on the node type, and follows roughly the same algorithm i described above.
Also this guide has info about how to write yor own deserialzer and registering it.