How can I deserialize JSON string that contains enum values that are case insensitive? (using Jackson Databind)
The JSON string:
[{"url": "foo", "type": "json"}]
and my Java POJO:
public static class Endpoint {
public enum DataType {
JSON, HTML
}
public String url;
public DataType type;
public Endpoint() {
}
}
in this case,deserializing the JSON with "type":"json"
would fail where as "type":"JSON"
would work.
But I want "json"
to work as well for naming convention reasons.
Serializing the POJO also results in upper case "type":"JSON"
I thought of using @JsonCreator
and @JsonGetter:
@JsonCreator
private Endpoint(@JsonProperty("name") String url, @JsonProperty("type") String type) {
this.url = url;
this.type = DataType.valueOf(type.toUpperCase());
}
//....
@JsonGetter
private String getType() {
return type.name().toLowerCase();
}
And it worked. But I was wondering whether there's a better solutuon because this looks like a hack to me.
I can also write a custom deserializer but I got many different POJOs that use enums and it would be hard to maintain.
Can anyone suggest a better way to serialize and deserialize enums with proper naming convention?
I don't want my enums in java to be lowercase!
Here is some test code that I used:
String data = "[{\"url\":\"foo\", \"type\":\"json\"}]";
Endpoint[] arr = new ObjectMapper().readValue(data, Endpoint[].class);
System.out.println("POJO[]->" + Arrays.toString(arr));
System.out.println("JSON ->" + new ObjectMapper().writeValueAsString(arr));
This is now very simple, using jackson-databind
2.9.0 and above
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.enable(MapperFeature.ACCEPT_CASE_INSENSITIVE_ENUMS);
// objectMapper now deserializes enums in a case-insensitive manner
Full example with tests
import com.fasterxml.jackson.databind.MapperFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
public class Main {
private enum TestEnum { ONE }
private static class TestObject { public TestEnum testEnum; }
public static void main (String[] args) {
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.enable(MapperFeature.ACCEPT_CASE_INSENSITIVE_ENUMS);
try {
TestObject uppercase =
objectMapper.readValue("{ \"testEnum\": \"ONE\" }", TestObject.class);
TestObject lowercase =
objectMapper.readValue("{ \"testEnum\": \"one\" }", TestObject.class);
TestObject mixedcase =
objectMapper.readValue("{ \"testEnum\": \"oNe\" }", TestObject.class);
if (uppercase.testEnum != TestEnum.ONE) throw new Exception("cannot deserialize uppercase value");
if (lowercase.testEnum != TestEnum.ONE) throw new Exception("cannot deserialize lowercase value");
if (mixedcase.testEnum != TestEnum.ONE) throw new Exception("cannot deserialize mixedcase value");
System.out.println("Success: all deserializations worked");
} catch (Exception e) {
e.printStackTrace();
}
}
}