Using Jackson with Map<String, Serializable>

user_1737718 0
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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
jackson json java
2 Answers

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.

user_76943280

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.

user_9354040
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