How to make enum parameter lowercase in SpringBoot/Swagger? - spring-boot

Question

I have the following endpoint
#GetMapping(value = "/mypath/{mychoice}")
public ResponseClass generateEndpoint(
#PathVariable("mychoice") FormatEnum format,
) {
...
and the following enum annotated with Jackson
#JsonNaming(PropertyNamingStrategies.KebabCaseStrategy.class)
public enum Format {
AVRO,
ORC,
PARQUET,
PROTOBUF
}
I hoped, #JsonNaming annotation will tell swagger to display cases in lowercase, but it doesn't
Adding #JsonProperty to each case also doesn't help.
It also doesn't accept lowercase URL with error
org.springframework.beans.TypeMismatchException: Failed to convert value of type 'java.lang.String' to required type 'FormatEnum'; nested exception is org.springframework.core.convert.ConversionFailedException: Failed to convert from type [java.lang.String] to type [#org.springframework.web.bind.annotation.RequestParam FormatEnum] for value 'avro'; nested exception is java.lang.IllegalArgumentException: No enum constant FormatEnum.avro
Setting
spring.jackson.mapper.ACCEPT_CASE_INSENSITIVE_ENUMS = true
has no effect (and is true in code).
Looks like it just doesn't use Jackson to deserialize enum!

Answer 1

Answering the part for serializing Enum case insensitive
The reason why setting spring.jackson.mapper.ACCEPT_CASE_INSENSITIVE_ENUMS=true is not working can be found in Konstantin Zyubin's answer.
And inspired from above answer, we can have a more generic approach to handle case insensitive enums in request parameter.
Converter class
import org.springframework.core.convert.converter.Converter;
public class CaseInsensitiveEnumConverter<T extends Enum<T>> implements Converter<String, T> {
private Class<T> enumClass;
public CaseInsensitiveEnumConverter(Class<T> enumClass) {
this.enumClass = enumClass;
}
#Override
public T convert(String from) {
return T.valueOf(enumClass, from.toUpperCase());
}
}
Add in configuration
import com.example.enums.EnumA;
import com.example.enums.EnumB;
import com.example.enums.FormatEnum;
import org.springframework.context.annotation.Configuration;
import org.springframework.format.FormatterRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import java.util.List;
#Configuration
public class AppConfig implements WebMvcConfigurer {
#Override
public void addFormatters(FormatterRegistry registry) {
List<Class<? extends Enum>> enums = List.of(EnumA.class, EnumB.class, FormatEnum.class);
enums.forEach(enumClass -> registry.addConverter(String.class, enumClass,
new CaseInsensitiveEnumConverter<>(enumClass)));
}
}
Related: Jackson databind enum case insensitive