问题描述

有没有办法使用定义的注释定义 Hibernate 验证规则 这里，说明至少有一个字段不能为空?

Is there a way to define a Hibernate validation rule using annotations as defined here, stating that at least one field shall be not null?

这将是一个假设示例(@OneFieldMustBeNotNullConstraint 并不真正存在):

This would be a hypothetical example (@OneFieldMustBeNotNullConstraint does not really exist):

@Entity
@OneFieldMustBeNotNullConstraint(list={fieldA,fieldB})
public class Card {

    @Id
    @GeneratedValue
    private Integer card_id;

    @Column(nullable = true)
    private Long fieldA;

    @Column(nullable = true)
    private Long fieldB;

}

在图示的情况下，fieldA 可以为 null 或 fieldB 可以为 null，但不能同时为 null.

In the illustrated case, fieldA can be null or fieldB can be null, but not both.

一种方法是创建我自己的验证器，但如果它已经存在，我想避免.如果您已经制作了一个验证器，请分享一个...谢谢！

One way would be to create my own validator, but I'd like to avoid if it already exists. Please share one validator if you have one already made... thanks!

推荐答案

我终于写出了整个验证器:

I finally wrote the whole validator:

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

import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;

import javax.validation.Constraint;
import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
import javax.validation.Payload;

import org.apache.commons.beanutils.PropertyUtils; 

@Target( { TYPE })
@Retention(RUNTIME)
@Constraint(validatedBy = CheckAtLeastOneNotNull.CheckAtLeastOneNotNullValidator.class)
@Documented
public @interface CheckAtLeastOneNotNull {
    
     String message() default "{com.xxx.constraints.checkatleastnotnull}";

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

     Class<? extends Payload>[] payload() default {};
        
     String[] fieldNames();
        
     public static class CheckAtLeastOneNotNullValidator implements ConstraintValidator<CheckAtLeastOneNotNull, Object> {
            
         private String[] fieldNames;

         public void initialize(CheckAtLeastOneNotNull constraintAnnotation) {
             this.fieldNames = constraintAnnotation.fieldNames();
         }

         public boolean isValid(Object object, ConstraintValidatorContext constraintContext) {

             if (object == null) {
                 return true;
             }
             try { 
                 for (String fieldName:fieldNames){
                     Object property = PropertyUtils.getProperty(object, fieldName);
                        
                     if (property != null) return true;
                 }
                 return false;
             } catch (Exception e) {
                 return false;
             }
         }
     }
}

使用示例:

@Entity
@CheckAtLeastOneNotNull(fieldNames={"fieldA","fieldB"})
public class Reward {

    @Id
    @GeneratedValue
    private Integer id;

    private Integer fieldA;
    private Integer fieldB;

    [...] // accessors, other fields, etc.
}

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