On Sat, Jan 26, 2019 at 7:08 PM C-B-B <[email protected]> wrote:
>
> Hello folks,
>
> I've been trying to serialise and deserialise a Map<String, Object> whilst
> preserving the type of the elements, for example a Long should remain a Long
> and not become an Integer.
> This works pretty well using the @JsonTypeInfo annotation on the Map. Jackson
> is being clever, and only including the type info when it is needed (e.g. it
> won't include it on an Integer, String, Double etc as they are default
> deserialisation types anyway), which is nice.
> There's however a nasty edge case with Double.NaN, Double.POSITIVE_INFINITY
> and Double.NEGATIVE_INFINITY: they get serialised without type info, and get
> deserialised as Strings...
>
> I've raised this as an issue, but in the meantime I'm looking for a
> workaround to include the type info on these Doubles (I've checked, and the
> deserialisation of NaN and infinity values works fine if the type is
> included).
> Ideally, the customised code would only be invoked for that Map object,
> rather that for all serialisations (I've been able to override the
> DoubleSerializer altogether on the ObjectMapper, but would rather not make
> such an invasive change).
I agree that this is a bug, and hope to eventually resolve it as per
issue filed.
But in the meantime I do think that custom deserializer is the way to
go; and there's no easy way to change to only occur for Map values
(delegation model means that same DoubleDeserializer is used for
properties and map values).
-+ Tatu +-
>
> I've tried a few things, including with TypeIdResolver, but no luck so far...
> Any help would be much appreciated!
>
> Here's a little repro
>
> import com.fasterxml.jackson.annotation.JsonTypeInfo;
> import com.fasterxml.jackson.databind.ObjectMapper;
> import java.io.IOException;
> import java.util.HashMap;
> import java.util.Map;
>
> public class Repro {
> private static ObjectMapper objectMapper = new ObjectMapper();
>
> public static void main(String[] args) {
> try {
> String beanString = objectMapper.writeValueAsString(new Bean(1L,
> Double.NaN));
> MapHolder beanOut = objectMapper.readValue(beanString,
> MapHolder.class);
> System.out.println(beanOut.data.get("double").getClass());
> beanString = objectMapper.writeValueAsString(new Bean(1L, 1D));
> beanOut = objectMapper.readValue(beanString, MapHolder.class);
> System.out.println(beanOut.data.get("double").getClass());
> } catch (IOException e) {
> e.printStackTrace();
> }
> }
>
> public static class Bean {
> private Long longValue;
> private Double doubleValue;
>
> public Bean(Long longValue, Double doubleValue) {
> this.longValue = longValue;
> this.doubleValue = doubleValue;
> }
>
> @JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, include =
> JsonTypeInfo.As.PROPERTY, property = "@class")
> public Map<String, Object> getData() {
> Map<String, Object> map = new HashMap<>();
> map.put("long", longValue);
> map.put("double", doubleValue);
> return map;
> }
> }
>
> public static class MapHolder {
> public Map<String, Object> data;
> MapHolder() {}
> }
> }
>
>
>
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