Issue handling unknown/unmapped Enum keys

[remya11]

Hi,

Trying to deserialize a JSON string using jackson-databind Objectmapper which has a set of Enum attributes within it, but ends up in InvalidFormatException.

This happens when an unknown attribute, which is not defined in the enum comes in the JSON.

    ObjectMapper objectMapper = new ObjectMapper();
    objectMapper.setVisibility(PropertyAccessor.ALL, Visibility.NONE);
    objectMapper.setVisibility(PropertyAccessor.FIELD, Visibility.ANY);
    objectMapper.setSerializationInclusion(Include.NON_NULL);
   objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);

But, deserialization (objectMapper.readValue(jsonText, .class);) throws an error. "Test" is the unknown attribute that comes in the JSON String to be deserialized.

com.fasterxml.jackson.databind.exc.InvalidFormatException: Cannot deserialize Map key of type com..* from String "Test": not a valid representation, problem:(com.fasterxml.jackson.databind.exc.InvalidFormatException) Cannot deserialize Map key of type com.... from String "Test": not one of values excepted for Enum class: [ ]

Sample of JSON String would look like this.

String jsonText="{\"cartId\":\"31028\",\"userId\":\"106784\",\"attributes\":{\"count\":\"1\",\"amount\":\"10\",\"email\":\"N\",\"Test\":\"No\",\"phone\":\"N\"}}";

The JSON maps to a Cart class, which holds these attributes as a Map.

public class Cart {
  private String cartId;
  private String userId;
  private Map<Attributes,String> attributes;
}

Attributes map to the Enum, as given below.

public enum Attributes {
  Count(0),
  Amount(1),
  Email(2),
  Phone(3);

  private final int value;
  private Attributes(int value) {
    this.value = value;
  }
  public int getValue() {
    return value;
  }
}

Also tried adding this configuration

objectMapper.configure(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL, true);

This resulted in the Unknown attribute key to be deserialized as null. (i.e., instead of Test=No, it gets deserialized as null=No). So, when a new attribute - say, 'Test' comes in the Json, it would be good if the mapper can ignore that field and proceed with de-serializing the remaining fields that has a match in the Enum, rather than throwing the exception.

[remya11]

Hi,

Could you please let me know when this fix could be available?

Regards,
Remya

[cowtowncoder]

@remya11 if and when someone has time and interest to work on this.

[cowtowncoder]

Ok working on this. One quick note: if you declare map as EnumMap, things actually work the way you'd like when DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL is enabled.
When type is basic Map the problem is that null is valid key value.

Handling of "as default" is not working so I will try to fix that, but I will not change the way key handling works for simple Map.

Note that you could also consider custom Map sub-class that would simply change put method to ignore attempts to add entries with null as key.

[cowtowncoder]

So: handling READ_UNKNOWN_ENUM_VALUES_AS_NULL not changed as it was working as specified (but handling subtly different for EnumMap). Fixed handling so that EnumKeyDeserializer honors READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE as well.

[isuribb]

Tried using the "READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE " with the JsonEnumDefaultValue annotation. It worked for the type Enum as expected. Then we have another issue where we are using a Map<Enum,String> object in our Bean class which didnot get resolved with above. When tried debugging, noticed the following code is going inside the class, EnumResolver since we a . It would be good if we can handle the same default value handling done in EnumDeserializer class , on this class as well so that we can use the default value we have defined. Appreciate a quick response.. Thank you.

StdKeyDeserializer :
@OverRide
public Object _parse(String key, DeserializationContext ctxt) throws IOException
{
if (_factory != null) {
try {
return _factory.call1(key);
} catch (Exception e) {
ClassUtil.unwrapAndThrowAsIAE(e);
}
}
EnumResolver res = ctxt.isEnabled(DeserializationFeature.READ_ENUMS_USING_TO_STRING)
? _getToStringResolver(ctxt) : _byNameResolver;
Enum<?> e = res.findEnum(key);
if ((e == null) && !ctxt.getConfig().isEnabled(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL)) {
return ctxt.handleWeirdKey(_keyClass, key, "not one of values excepted for Enum class: %s",
res.getEnumIds());
// fall-through if problems are collected, not immediately thrown
}
return e;
}