在 Spring Boot 控制器中反序列化枚举忽略大小写

Question

I have Spring Boot endpoint which has enum as query param:

@GetMapping("/example")
public List<Example> getByEnum(@RequestParam(name = "exampleEnum", required = false) ExampleEnum exampleEnum) {
    // code
}

And enum class:

public enum ExampleEnum {
    FIRST,
    SECOND,
}

If I pass uppercase enum value to the endpoit, it deserializes well but it throws error for lowercase:

java.lang.IllegalArgumentException: No enum constant 

How to deserialize enum ignoring case in Spring Boot Rest endpoint?

This question is not duplicate because it's related to query param deserialization.

Answer 1

EDIT: The answer below is incorrect. You have to define a custom PropertyEditor and register it with Spring @InitBinder which I explained in this post . Thanks to @Dave for pointing this out in the comments.

---

Spring Boot 2.0 is using Jackson 2.9 which has ACCEPT_CASE_INSENSITIVE_ENUMS feature. You should be able to enable it by setting

spring.jackson.mapper.ACCEPT_CASE_INSENSITIVE_ENUMS = true 

property as per docs, Appendix A .

Answer 2

import com.fasterxml.jackson.annotation.JsonCreator;
import java.util.Arrays;
import java.util.Optional;

public enum ExampleEnum {
    FIRST,
    SECOND;

    @JsonCreator
    public static ExampleEnum setValue(String key) {
        return Arrays.stream(ExampleEnum.values())
            .filter(exampleEnum -> exampleEnum.toString().equals(key.toUpperCase()))
            .findAny()
            .orElse(null);
}

Answer 3

You can make generic converter for all enums

package ru.grancall.kb.logging.service.dto.converter;

import lombok.AllArgsConstructor;
import org.apache.commons.lang3.EnumUtils;
import java.beans.PropertyEditorSupport;

@AllArgsConstructor
public class EnumConverter extends PropertyEditorSupport {
    private Class type;

    public void setAsText(String text) {
        setValue(EnumUtils.getEnum(type, text.toUpperCase()));
    }
}

And then in any of your Controllers use it:

@InitBinder
    public void initBinder(WebDataBinder dataBinder) {
        dataBinder.registerCustomEditor(YourEnum.class, new EnumConverter(YourEnum.class));
    }

Answer 4

If you want to get ALL your enums handled case-insensitively you can use Spring's ApplicationConversionService .

You only have to register it with the following little Configuration (see baeldung ):

@Configuration
public class EnumMappingConfig implements WebMvcConfigurer {
    @Override
    public void addFormatters(FormatterRegistry registry) {
        ApplicationConversionService.configure(registry);
    }
}