did anyone tried to find a good solution to automatically convert all empty strings to null object on deserialization using JsonB (Yasson)?
I encountered this problem on migration from Jackson to Jsonb where empty string value in request produces deserialization exception since it cannot be parsed to object.
HTTP request payload:
{
fieldNameUid: '', // Java property is UUID type
}
Jackson had the following configuration:
public void customize(ObjectMapper mapper) {
mapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
mapper.enable(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL);
SimpleModule module = new SimpleModule();
module.addDeserializer(
String.class,
new StdDeserializer<>(String.class) {
@Override
public String deserialize(JsonParser parser, DeserializationContext context)
throws IOException {
String result = StringDeserializer.instance.deserialize(parser, context);
if (result == null || result.isBlank()) {
return null;
}
return result;
}
});
module.addDeserializer(byte[].class,
new StdDeserializer<>(byte[].class) {
@Override
public byte[] deserialize(JsonParser parser, DeserializationContext context)
throws IOException {
String result = StringDeserializer.instance.deserialize(parser, context);
if (result == null || result.isBlank()) {
return null;
}
return result.getBytes(StandardCharsets.UTF_8);
}
});
mapper.registerModule(module);
}
and current Jsonb config:
public class JsonbObjectMapper implements JsonbConfigCustomizer {
@Override
public void customize(JsonbConfig jsonbConfig) {
jsonbConfig
.withDeserializers(new StringDeserializer(), new ByteArrayDeserializer(), new EnumDeserializer())
.withSerializers(new EnumSerializer());
}
public static class StringDeserializer implements JsonbDeserializer<String> {
@Override
public String deserialize(javax.json.stream.JsonParser jsonParser, javax.json.bind.serializer.DeserializationContext deserializationContext, Type type) {
final String str = jsonParser.getString();
return str == null || str.isBlank() ? null : str;
}
}
public static class ByteArrayDeserializer implements JsonbDeserializer<byte[]> {
@Override
public byte[] deserialize(javax.json.stream.JsonParser jsonParser, javax.json.bind.serializer.DeserializationContext deserializationContext, Type type) {
final String str = jsonParser.getString();
return str == null || str.isBlank() ? null : str.getBytes(StandardCharsets.UTF_8);
}
}
public static class EnumDeserializer implements JsonbDeserializer<Enum> {
@Override
public Enum deserialize(javax.json.stream.JsonParser jsonParser, javax.json.bind.serializer.DeserializationContext deserializationContext, Type type) {
final String str = jsonParser.getString();
if (str == null || str.isBlank()) {
return null;
}
for (final Enum en : ((Class<Enum>) type).getEnumConstants()) {
if (en.toString().equals(str)) {
return en;
}
}
return null;
}
}
public static class EnumSerializer implements JsonbSerializer<Enum> {
@Override
public void serialize(Enum anEnum, JsonGenerator jsonGenerator, SerializationContext serializationContext) {
jsonGenerator.write(anEnum == null ? null : anEnum.toString());
}
}
}
