Mapping the different type of values for one field in JSON to java object using Jackson

Question

We have a json where for a particular field the data type is different. I want to map it to Java Object using jackson. If the fields are of one type i am able to do it. but for different type unable to find a way.

{
    "firstname": "first_name",
    "age": "34",
    "add_info": [{
            "type": "type_a",
            "value": "value_a"
        },
        {
            "type": "type_b",
            "value": [{
                    "title": "info_1",
                    "desc": "desc_1"
                },
                {
                    "title": "info_2",
                    "desc": "desc_2"
                }
            ]
        }
    ]
}

POJO: Basically with this POJO i dont know how to define it

public class AddInfo {
private String type;
private List<Value> value = null;
//getter and setters
}

In the above JSON for add_info field it contains array of JSON object wherein first object value is of type string and second value holds an array of object.

How to handle this kind of situation in Pojo using jackson

Make a class for List<Value> and write a custom deserializer — Eklavya
– Eklavya, Commented Aug 7, 2020 at 19:58

aeberhart · Accepted Answer · 2020-08-07 20:25:10Z

1

If you do not want to write a custom deserializer, you could simply use an Object field:

public class AddInfo {

  public String type;
  public Object value;

  public static void main(String[] args) throws Exception {
    ObjectMapper om = new ObjectMapper();
    AddInfo i1 = om.readValue("{\"value\":\"string\"}", AddInfo.class);
    System.out.println(i1.value);
    AddInfo i2 = om.readValue("{\"value\":[{\"x\":1}]}", AddInfo.class);
    System.out.println(i2.value);
  }
}

In the first run, i1.value is a String. In the second run, i2.value is a list of hashmaps. So you loose the Pojo structure.

answered Aug 7, 2020 at 20:25

aeberhart

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1 Comment

anand Over a year ago

list of hashmap means it will be like x as key and 1 as value

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