CODEWITHSUNDEEP
javajsonjacksondeserialization
dd483pe
dd483pe

Reputation: 85

JSON Jackson deserialization multiple keys into same field

I am trying to convert JSON into POJO. I have worked with Jackson to convert standard JSON file. In this particular case, I would like to overwrite the key value to "default" class/variable. In this case, there are multiple key value to be replaced (ie. hundreds, and the key values to be replaced are unknown).

Is this possible? I thought of storing it into Map, then iterate and store each into POJO, but wondering if there is different option, since I am not that familiar with storing JSON to Map.

Example of the JSON to be processed:

"People" : {
    "person1" : { 
      "name" : "john doe",
      "address" : "123 main st",
      "email" : "[email protected]"
    },
    "person2" : { 
      "name" : "bob cat",
      "address" : "234 dog st",
      "email" : "[email protected]"
    },
    "person3" : { 
      "name" : "foo bar",
      "address" : "111  1st ave",
      "email" : "[email protected]"
    },
    "person8" : { 
      "name" : "james bono",
      "address" : "999 alaska st",
      "email" : "[email protected]"
    }
}

Is it possible to generate the class in the following structure? The main issue is there are hundreds of value to be replaced and assuming they are unknown, I can't use this approach.

@JsonIgnoreProperties(ignoreUnknown = true)
public class People { 

  @JsonAlias({"person1", "person2"})
  private List<Details> person; // --> this should be the default replacing person1, person2, and so on 

  private class Details { 
    String name;
    String address;
    String email;
  }
}

Upvotes: 4

Views: 4343

Answers (2)

Vargan
Vargan

Reputation: 1327

Just adding my two cents. I think this way looks nicer and is also easy to retrieve data. Jackson will do the deserialization without the need of any other tags or custom code, and it's all nice and sorted in a hashmap.

class People {

    private Map<String, Person> persons = new HashMap<>();

    // getter and setters
}

public class Person {
    String name;
    String address;
    String email;

    // getters and setters
}

}

Upvotes: 0

Michał Ziober
Michał Ziober

Reputation: 38710

You can use JsonAnySetter annotation for all properties personXYZ. See below example:

import com.fasterxml.jackson.annotation.JsonAnySetter;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.io.File;
import java.util.ArrayList;
import java.util.List;

public class JsonApp {

    public static void main(String[] args) throws Exception {
        File jsonFile = new File("./resource/test.json").getAbsoluteFile();

        ObjectMapper mapper = new ObjectMapper();
        mapper.enable(DeserializationFeature.UNWRAP_ROOT_VALUE);

        System.out.println(mapper.readValue(jsonFile, People.class).getPersons());
    }
}

class People {

    private List<Details> persons = new ArrayList<>();

    @JsonAnySetter
    public void setPerson(String name, Details person) {
        this.persons.add(person);
    }

    public List<Details> getPersons() {
        return persons;
    }

    public static class Details {
        String name;
        String address;
        String email;

        // getters, setters, toString
    }
}

For your JSON above code prints:

[Details{name='john doe', address='123 main st', email='[email protected]'}, Details{name='bob cat', address='234 dog st', email='[email protected]'}, Details{name='foo bar', address='111  1st ave', email='[email protected]'}, Details{name='james bono', address='999 alaska st', email='[email protected]'}]

In case you use inner class remember to make it public static to make it visible to Jackson instantiation process.

See also:

Upvotes: 5

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