FasterXML / FasterXML/jackson-modules-base
NoCtorDeser can not deserialize parameterized types
- Dominant language
- Java
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Description
# Code
The following code throws java.lang.ClassCastException. The type of `response.getPayload()` is not `User` but `LinkedHashMap`
```java
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectReader;
import com.fasterxml.jackson.databind.json.JsonMapper;
import com.fasterxml.jackson.module.noctordeser.NoCtorDeserModule;
public class Demo {
public static class Response {
private final T payload;
public Response(T payload) {
this.payload = payload;
}
public T getPayload() {
return payload;
}
}
public static class User {
private final String name;
public User(String name) {
this.name = name;
}
public String getName() {
return name;
}
}
public static void main(String[] args) throws Exception {
String json = "{\"payload\":{\"name\":\"jackson\"}}";
JsonMapper mapper = JsonMapper.builder()
.addModule(new NoCtorDeserModule())
.build();
ObjectReader objectReader = mapper.readerFor(new TypeReference>() {
});
Response response = objectReader.readValue(json);
System.out.println(response.getPayload().getClass());
}
}
```
# Cause
@cowtowncoder It seems the JsonDeserializer is fetched by `Class instClass` rather than a ParameterizedType.
https://github.com/FasterXML/jackson-modules-base/blob/2.15/no-ctor-deser/src/main/java/com/fasterxml/jackson/module/noctordeser/MissingInstantiatorHandler.java#L34-L37
# Solution
The overrided method `DeserializationProblemHandler#handleMissingInstantiator(DeserializationContext ctxt, Class instClass, ValueInstantiator valueInst, JsonParser jsonParser, String msg)` does not suppy generic information. Maybe we can extend class AnnotatedWithParams and override its `public abstract Object call() throws Exception;`. Then we set it to the StdValueInstantiator's _defaultCreator field?
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