Android using MSGPack Core and Jackson Mapper - decode class variable of unknown type

Question

I am sending/receiving a custom class from a server to Android, the class is as;

import org.msgpack.value.Value;
public class myClass {

    public String status;
    public Value data;

}

The problem is that I always get the error;

com.fasterxml.jackson.databind.JsonMappingException: Can not construct instance of org.msgpack.value.Value, problem: abstract types either need to be mapped to concrete types, have custom deserializer, or be instantiated with additional type information
        at [Source: java.io.BufferedInputStream@f478759; line: -1, column: 100] (through reference chain:xxx.xxxxxxxxxx.xxx.xxxxxx.myClass["data"]

If I change the variable "data" to say MAP<String, String> data then it works fine, however, data is of an unknown type! (well normally HashMap or an Array maybe a String, not some other class).

MessagePackFactory factory = new MessagePackFactory();
ObjectMapper mapper = new ObjectMapper(factory);
myClass response = mapper.readValue(inputStream, myClass.class);

How can I specify an unknown type?

score 2 · Accepted Answer · answered Jan 04 '16 at 17:00

2

So I changed the class to;

public class myClass{

    public String status;
    public Object data;

}

And I now just test the Object type. I am not sure why I did not try this before!

answered Jan 04 '16 at 17:00

Recycled Steel

2,272
3
30
35

Because now I do not have a nice data.getInteger function. – Recycled Steel Jan 05 '16 at 09:25

score 1 · Answer 2 · answered Jan 08 '16 at 23:16

1

org.msgpack.value.Value is an interface.

When you are de-serializing values using ObjectMapper, the target must be a Class with Default Constructor. Other wise OM cannot create a target Object.

answered Jan 08 '16 at 23:16

Srikanth K.

742
5
16

But if I do not know what "data" type is going to be how can I create a Constructor? – Recycled Steel Jan 11 '16 at 09:51

Android using MSGPack Core and Jackson Mapper - decode class variable of unknown type

2 Answers2