How to conditionally convert JSON to an array during deserialization

[Tristan Burch]

Hi,

I've been trying to figure this out, but haven't had any luck yet, so I thought I'd post here for some help...

I have the following JSON, where the 'response' field can either be an object or a collection of those objects:

{

    "success": false,

    "error": {

        "code": "invalid_location",

        "description": "The requested location was not found in the database."

    },

    "response": [ ]

}

I'd like to map the JSON to the following POJO:

public abstract class Response<T> {

  private boolean success;

  private Error error;

  private Collection<T> response;

}

Is there a way to write a conditional deserializer that will check to see if 'response' is an object and if so, convert it to a collection of those objects? I've looked at @JsonDeserialize and the converters, but couldn't get it to do what I wanted.

Thanks!

-Tristan

[Tatu Saloranta]

I think what you are looking for would be

 DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY

which will allow general mapping of a single Object into List/array of Objects (with matching content type).

Or, with Jackson 2.6, you can also define it on per-property basis, like:

class Response<T> {
   ...

   @JsonFormat(with=JsonFormat.Feature.ACCEPT_SINGLE_VALUE_AS_ARRAY)

   private Collection<T> response
}

which may be nice if you only want to allow for specific properties.

-+ Tatu +-

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[Tristan Burch]

Thanks Tatu!