Consider making enum serialisation consistent with Spring

[martin-walsh]

Is your feature request related to a problem? Please describe.

• Rendering of enums (using Jackson) is implemented differently in spring and swagger-core.
• Spring respects @JsonValuewhile swagger-core does not.

Describe the solution you'd like

• Add out of the box PropertyCustomizer to make rendering consistent.

Example

    public PropertyCustomizer enumValuePropertyCustomizer() {
        return (property, type) -> {

            var javaType = (JavaType) type.getType();

            if (javaType.isEnumType()) {
                var rawClass = javaType.getRawClass();

                // Json.mapper() is the underlying jackson ObjectMapper singleton used by swagger-core
                var beanDesc = Json.mapper().getSerializationConfig().introspect(javaType);

                // Same implementation as Spring.
                var accessor = beanDesc.findJsonValueAccessor();

                if (accessor == null) {
                    return property;
                }

                if (property instanceof StringSchema) {
                    var values = Arrays.stream(rawClass.getEnumConstants())
                        .map(accessor::getValue)
                        .map(Object::toString)
                        .collect(Collectors.toList());

                    // Replace rather than add to the values, including discarding allowableValues option, as Enums will not allow any other content anyway in either request or response
                    property.setEnum(values);
                }
            }

            return property;
        };
    }

[bnasslahsen]

@martin-walsh,

It's an interesting feature.
Are you willing to propose a PR for it?

[martin-walsh]

Sure, will submit today or tomorrow

[bnasslahsen]

@martin-walsh,

I am closing this ticket as there is no activity.
If any PR is submitted, we can link it to this ticket.

[NicklasWallgren]

@martin-walsh @bnasslahsen Is it possible to customize method parameters as well, to serialize the enum using the @JsonValue annotation?

Do I need to implement a DelegatingMethodParameterCustomizer, or subclass DataRestDelegatingMethodParameterCustomizer to apply the same logic too @PathVariable parameters?

[bnasslahsen]

@NicklasWallgren,

I am not aware about your context to answer.
You can look on stackoverflow, or in the previous issues on github.

If you provide the necessary information described in the contribution guide, i might help.

This is the guidance, and mainly the information in the section Using GitHub Issues.

[NicklasWallgren]

@bnasslahsen Thanks for the response. I actually got it working.

It seems like io.swagger.v3.core.jackson.ModelResolver already supports the JsonValue annotation, so we don't need to apply a custom PropertyCustomizer, like @martin-walsh suggested.

Sorry for hijacking the issue.

[mjustin]

One workaround is to use @JsonProperty instead of @JsonValue:

import com.fasterxml.jackson.annotation.JsonProperty;

public enum Suit {
    @JsonProperty("Hearts") HEARTS,
    @JsonProperty("Diamonds") DIAMONDS,
    @JsonProperty("Clubs") CLUBS,
    @JsonProperty("Spades") SPADES;
}