Spring parse String to enum before entering the controller

Question

I have the following controller:

public interface SaveController {
  @PostMapping(value = "/save")
  @ResponseStatus(code = HttpStatus.CREATED)
  void save(@RequestBody @Valid SaveRequest saveRequest);
}

SaveRequest corresponds to:

public class SaveRequest {
  @NotNull
  private SaveType type;

  private String name;
}

and SaveType:

public enum SaveType {
  DAILY, WEEKLY, MONTHLY;
}

The controller does not receive the enum itself, but a camelCase String. I need to convert that String into the corresponding enum. For instance:

daily should become DAILY.
weekly should become WEEKLY.
monthly should become MONTHLY.
Any other String should become null.

I've tried using the Spring Converter class, which does not work when the enum is inside an object (at least I don't know how to make it work in such times).

I honestly don't know what else to try

Litrico · Accepted Answer · 2021-03-12 13:44:40Z

3

https://www.baeldung.com/jackson-serialize-enums This site should probably give you plenty of options.

Best is probably something like this:

public enum SaveType {
    
    DAILY, WEEKLY, MONTHLY;

    @JsonCreator
    public static SaveType saveTypeforValue(String value) {
        return SaveType.valueOf(value.toUpperCase());    
    }
}

answered Mar 12, 2021 at 13:44

Litrico

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Comments

Naveen Vignesh · Accepted Answer · 2021-03-12 13:44:29Z

-1

What you require is to have custom annotation with a custom validation class for Enum.

javax.validation library doesn't have inbuilt support for enums.

Validation class

public class SaveTypeSubSetValidator implements ConstraintValidator<SaveTypeSubset, SaveType> {
    private SaveType[] subset;

    @Override
    public void initialize(SaveTypeSubset constraint) {
        this.subset = constraint.anyOf();
    }

    @Override
    public boolean isValid(SaveType value, ConstraintValidatorContext context) {
        return value == null || Arrays.asList(subset).contains(value);
    }
}

interface for validation annotation with validation message

@Target({METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE})
@Retention(RUNTIME)
@Documented
@Constraint(validatedBy = SaveTypeSubSetValidator.class)
public @interface SaveTypeSubset {
    SaveType[] anyOf();
    String message() default "must be any of {anyOf}";
    Class<?>[] groups() default {};
    Class<? extends Payload>[] payload() default {};
}

Usage

@SaveTypeSubset(anyOf = {SaveType.NEW, SaveType.OLD})
private SaveType SaveType;

This is one way. More ways are mentioned in this article.

answered Mar 12, 2021 at 13:44

Naveen Vignesh

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1 Comment

M. Deinum Over a year ago

Validation isn't going to help in the conversion.

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