CODEWITHSUNDEEP
javajsonjackson
cjamesm
cjamesm

Reputation: 109

Using Jackson with Map<String, Serializable>

I want to know if there is some way to get the following deserializing properly:

public class MyClass {
     Map<String, Serializable> map;
     OtherObject object;
     [...]
}

ObjectMapper mapper = new ObjectMapper();
MyClass instance = mapper.readValue(someJson, MyClass);

Currently, I'm trying and I get an exception 

com.fasterxml.jackson.databind.JsonMappingException: Can not construct instance of java.io.Serializable: abstract types either need to be mapped to concrete types, have custom deserializer, or contain additional type information

Upvotes: 3

Views: 578

Answers (2)

Sivaraam Subramanian
Sivaraam Subramanian

Reputation: 26

As of v2.10.0, Jackson supports naive deserialization of 'Serializable' values, i.e., it will consider 'Serializable' the same as 'Object'. See this Github issue for more details.

So update Jackson to 2.10.0+ and try.

Upvotes: 1

RichW
RichW

Reputation: 2024

You can change your data class's Map property declaration to not reference Serializable:

public class MyClass {
     Map<String, ?> map;
     OtherObject object;
     [...]
}

This will affect the signature of the Map's getter and setter as well. This does loosen type-checking, however, and the the map's values could be any subclass of Object instead of implementations of Serializable. If that's an important detail, you could do post-serialization validation of the map values.

Or you can configure a custom Deserializer, as those in your question's comments have suggested. It's just a matter of where you want to add the code, and that depends on how widespread this case is in your application.

Upvotes: 0

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