Deserialize json array values to specific Java class fields

Question

I have the following Json

    {
    "coreId" : "1",
    "name" : "name",
    "additionalValueList" : [
      {
       "columnName" : "allow_duplicate",
       "rowId"  : "10",
       "value" :  "1"
      },
      {
       "columnName" : "include_in_display",
       "rowId"  : "11",
       "value" :  "0"
      },
      ...e.t.c
     ]
 },
 ...e.t.c

and Java class

class DTO {
@JsonProperty("coreId")
private Integer id;

private String name;

private Boolean allowDuplicate;

private Boolean includeInDisplay;
}

How I can easily map values from 'additionalValueList' to corresponding java fields.For example Json value from field 'columnName' - 'allow_duplicate' = DTO.allowDuplicate. Actually I know how to do it with custom deserializers with @JsonDeserialize annotation and smth like this.Bu I have 40+ DTO and it is not a good idea to create own deserializer for each filed. I am looking for solution to have for example 1 deserializer(since values structure in 'additionalValueList' are the same for all entities) and to pass parameter(field name that I want to map to that field) to custom deserializer that will find in 'additionalValueList' entity with 'column Name' = parameter(that I passed from annotation) and return 'value'. Example

class DTO {
@JsonProperty("coreId")
private Integer id;

private String name;

@JsonDeserialize(using = MyCustDeser.class,param = allow_duplicate)
private Boolean allowDuplicate;

@JsonDeserialize(using = MyCustDeser.class,param = include_in_display)
private Boolean includeInDisplay;
}

It will be a good solution but maybe not easy to achieve.However I will be very grateful for all your advices.Thank you.

Answer 1

Create a Converter class, then specify it on the DTO class.

The following code uses public fields for the simplicity of the example.

/**
 * Intermediate object used for deserializing FooDto from JSON.
 */
public final class FooJson {

    /**
     * Converter used when deserializing FooDto from JSON.
     */
    public static final class ToDtoConverter extends StdConverter<FooJson, FooDto> {
        @Override
        public FooDto convert(FooJson json) {
            FooDto dto = new FooDto();
            dto.name = json.name;
            dto.id = json.coreId;
            dto.allowDuplicate = lookupBoolean(json, "allow_duplicate");
            dto.includeInDisplay = lookupBoolean(json, "include_in_display");
            return dto;
        }
        private static Boolean lookupBoolean(FooJson json, String columnName) {
            String value = lookup(json, columnName);
            return (value == null ? null : (Boolean) ! value.equals("0"));
        }
        private static String lookup(FooJson json, String columnName) {
            if (json.additionalValueList != null)
                for (FooJson.Additional additional : json.additionalValueList)
                    if (columnName.equals(additional.columnName))
                        return additional.value;
            return null;
        }
    }

    public static final class Additional {
        public String columnName;
        public String rowId;
        public String value;
    }

    public Integer coreId;
    public String name;
    public List<Additional> additionalValueList;
}

You now simply annotate the DTO to use it:

@JsonDeserialize(converter = FooJson.ToDtoConverter.class)
public final class FooDto {
    public Integer id;
    public String name;
    public Boolean allowDuplicate;
    public Boolean includeInDisplay;

    @Override
    public String toString() {
        return "FooDto[id=" + this.id +
                    ", name=" + this.name +
                    ", allowDuplicate=" + this.allowDuplicate +
                    ", includeInDisplay=" + this.includeInDisplay + "]";
    }
}

Test

ObjectMapper mapper = new ObjectMapper();
FooDto foo = mapper.readValue(new File("test.json"), FooDto.class);
System.out.println(foo);

Output

FooDto[id=1, name=name, allowDuplicate=true, includeInDisplay=false]