Is there a way to include nested Map with null values using Jackson

Question

I have a spring bean for ObjectMapper, and it has a configuration: mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL); I have class with a map inside:

@Getter
@Setter
@ToString
@EqualsAndHashCode
@NoArgsConstructor
@AllArgsConstructor
public class MyClass {
    private Map<String, Object> value = new HashMap<>();
}

and Map looks like:

{
  "value" : {
    "a": null,
    "b": "notnull",
    "c" : [ {
      "c1" : null
    }, {
      "c2" : "abc"
    } ]
  }
}

when I called rest endpoint, the response looks like:

"value": {
          "b": "notnull",
          "c": [
            {},
            {
              "c2": "abc"
            }
          ]
        }
      }

I tried to update config specific for my class:

JsonInclude.Include nonDefaultInclude = JsonInclude.Include.ALWAYS;
    JsonInclude.Value includeValue = JsonInclude.Value.construct(nonDefaultInclude, nonDefaultInclude);
    mapper.configOverride(MyClass.class).setIncludeAsProperty(includeValue);

but it is not working, whether it works, if I do something like:

JsonInclude.Include nonDefaultInclude = JsonInclude.Include.ALWAYS;
    JsonInclude.Value includeValue = JsonInclude.Value.construct(nonDefaultInclude, nonDefaultInclude);
    mapper.configOverride(Map.class).setIncludeAsProperty(includeValue);

I also tried to use 1st approach and put @JsonInclude on the map inside - no luck

if I will use 2nd approach, then I will override all Maps in the project - no way to do that.

Are the any way to achieve my goal?

Answer 1

You can control the Jackson ObjectMapper behavior from your application.properties file. To always include fields, regardless of their value, set the following configuration value:

spring.jackson.default-property-inclusion=always

Docs: Customize the Jackson ObjectMapper