Spring Boot 验证 - 一个从两个不为空

Question

我正在尝试验证 Spring Boot 中两个字段之一是否不为空？

我已经在主对象的方法类中设置了：

@NotNull(message = "Username field is required")
private String username;

@NotNull(message = "Email field is required")
private String email;

但这需要两个字段都不为空。然后我使用此处描述的自定义验证https://lmonkiewicz.com/programming/get-noticed-2017/spring-boot-rest-request-validation/，但我无法让该示例正常工作。我必须坚持

用户类声明：

@CombinedNotNull(fields = {"username","email"})
public class User implements {

    private long id = 0L;
    @NotNull(message = "First name field is required")
    private String firstName;

    @NotNull(message = "Last name field is required")
    private String lastName;

    private String username;
    private String email;

    @NotNull(message = "Status field is required")
    private String status;

    ...all methods here...
    ...setters and getters...

}

CombibnedNotNull 类：

@Documented
@Retention(RUNTIME)
@Target({ TYPE, ANNOTATION_TYPE })
@Constraint(validatedBy = userValidator.class)
public @interface CombinedNotNull {
        String message() default "username or email is required";
        Class<?>[] groups() default { };
        Class<? extends Payload>[] payload() default { };
}

userValidator 类：

@Component
public class userValidator implements ConstraintValidator<CombinedNotNull, User> {

    @Override
    public void initialize(final CombinedNotNull combinedNotNull) {
        fields = combinedNotNull.fields();
    }

    @Override
    public boolean isValid(final User user, final ConstraintValidatorContext context) {
        final BeanWrapperImpl beanWrapper = new BeanWrapperImpl(user);

        for (final String f : fields) {
            final Object fieldValue = beanWrapper.getPropertyValue(f);

            if (fieldValue == null) {
                return false;
            }
        }

        return true;
    }
}

还有其他方法可以完成这项工作，还是我应该使用该页面中的“复杂”示例？

Answer 1

我假设 username OR email 不能为空。不是XOR。

在User 类中添加这个getter：

@AssertTrue(message = "username or email is required")
private boolean isUsernameOrEmailExists() {
    return username != null || email != null;
}

根据我的经验，方法名称必须遵循 getter 名称约定，否则这将不起作用。例如，getFoo 或 isBar。

这有一个小问题：来自此验证错误的字段名称将是usernameOrEmailExists，只有 1 个错误字段。如果这不是问题，这可能会有所帮助。

---

但如果您希望在发生错误时拥有username 和email 字段，您可以使用此解决方法：

public String getUsername() {
    return username;
}

public String getEmail() {
    return email;
}

@AssertTrue(message = "username or email is required")
private boolean isUsername() {
    return isUsernameOrEmailExists();
}

@AssertTrue(message = "username or email is required")
private boolean isEmail() {
    return isUsernameOrEmailExists();
}

private boolean isUsernameOrEmailExists() {
    return username != null || email != null;
}

get... 方法只是一般用途的简单 getter，is... 用于验证。这将发出 2 个带有 username 和 email 字段的验证错误。

Answer 2

我会尝试为您实现它（即使我没有 IDE）。
在ConstraintValidator#initialize 中，您可以获取不能为null 的配置字段名称。

@Override
public void initialize(final CombinedNotNull combinedNotNull) {
    fields = combinedNotNull.fields();
}

在ConstraintValidator#isValid 中，您可以使用这些字段的名称来检查Object 字段。

@Override
public boolean isValid(final Object value, final ConstraintValidatorContext context) {
    final BeanWrapperImpl beanWrapper = new BeanWrapperImpl(value);
    
    for (final String f : fields) {
       final Object fieldValue = beanWrapper.getPropertyValue(f);
       
       if (fieldValue == null) {
          return false;
       }
    }

    return true;
}

注释：

import javax.validation.Constraint;
import javax.validation.Payload;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;

import static java.lang.annotation.RetentionPolicy.RUNTIME;

@Retention(RUNTIME)
@Target({ElementType.TYPE, ElementType.ANNOTATION_TYPE})
@Constraint(validatedBy = CombinedNotNullValidator.class)
public @interface CombinedNotNull {
    String message() default "username or email is required";

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

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

    /**
     * Fields to validate against null.
     */
    String[] fields() default {};
}

注释可以应用为

@CombinedNotNull(fields = {
      "fieldName1",
      "fieldName2"
})
public class MyClassToValidate { ... }

要了解如何创建类级约束注释，请始终参阅官方文档。 Docs

Answer 3

如果您想验证是否设置了一个而其他为空：

注释

import javax.validation.Constraint;
import javax.validation.Payload;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;

import static java.lang.annotation.RetentionPolicy.RUNTIME;

@Retention(RUNTIME)
@Target({ElementType.TYPE, ElementType.ANNOTATION_TYPE})
@Constraint(validatedBy = OneNotNullValidator.class)
public @interface OneNotNull {
    String message() default "Exactly one of the fields must be set and the other must be null";

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

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

    /**
     * Fields to validate against null.
     */
    String[] fields() default {};
}

验证器

import java.util.Arrays;
import java.util.Objects;

import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;

import org.springframework.beans.BeanWrapperImpl;
import org.springframework.stereotype.Component;

@Component
public class OneNotNullValidator implements ConstraintValidator<OneNotNull, Object> {
    private String[] fields;

    @Override
    public void initialize(final OneNotNull combinedNotNull) {
        fields = combinedNotNull.fields();
    }

    @Override
    public boolean isValid(final Object obj, final ConstraintValidatorContext context) {
        final BeanWrapperImpl beanWrapper = new BeanWrapperImpl(obj);

        return Arrays.stream(fields)
                .map(beanWrapper::getPropertyValue)
                .filter(Objects::isNull)
                .count()
                == 1;
    }
}

用法

@OneNotNull(
    fields = {"username","email"},
    message="Either username or email must be set"
)
public class User {

    private String username;
    private String email;

   // ...
}