Custom constraint validation annotation for MultipartFile

Question

I'm trying to make an annotation to validate a list of MultipartFile on the controller parameters, but it doesn't seem to make any effect. No exception is thrown, not error at all. I looked at some similar questions but it didn't work.

Interface:

@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy = {ImageValidator.class})
public @interface ValidImage {
  String message() default "Invalid image file";

  Class<?>[] groups() default {};

  Class<? extends Payload>[] payload() default {};
}

Class:

public class ImageValidator implements ConstraintValidator<ValidImage, List<MultipartFile>> {

  @Override
  public boolean isValid(
      List<MultipartFile> listMultipartFile, ConstraintValidatorContext context) {

    for (var multipartFile : listMultipartFile) {
      var contentType = multipartFile.getContentType();
      if (!isSupportedContentType(contentType)) {
        context.disableDefaultConstraintViolation();
        context
            .buildConstraintViolationWithTemplate("Only JPG and PNG images are allowed.")
            .addConstraintViolation();
        return false;
      }
    }

    return true;
  }

  private boolean isSupportedContentType(String contentType) {
    var supportedContents = List.of("image/jpg", "image/jpeg", "image/png");
    return supportedContents.contains(contentType);
  }
}

Usage:

@PostMapping(value = "images")
  public ResponseEntity<List<ExerciseImageDTO>> uploadImages(
      @RequestParam(value = "images", required = true) @ValidImage List<@Valid MultipartFile> images) {

    .......
    return ResponseEntity.ok(createdImages);
  }

You short of something to convert MultipartFile into images in post action. pls implement Converter to make it firstly. refer to https://stackoverflow.com/questions/7161215/spring-multipartfile-validation-and-conversion. — jacky-neo, Oct 22 '20 at 01:34

score 1 · Accepted Answer · answered Oct 22 '20 at 02:50

you need @Validated on your controller class like this

    @Controller
    @Validated
    public class SampleController {

      @PostMapping(value = "images")
      public ResponseEntity<List<ExerciseImageDTO>> uploadImages(
      @RequestParam(value = "images", required = true) @ValidImage List<@Valid MultipartFile> images) {
        .......
        return ResponseEntity.ok(createdImages);
      }

    }

Custom constraint validation annotation for MultipartFile

1 Answers1