如何在使用javax验证时，仅当字段不为null时对其应用自定义验证？

huangapple
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英文:

How to apply custom validation on a field using javax validation only if it is not null?

问题

我正在Spring Boot应用程序中使用javax验证API。我有一个用户实体（bean），我需要验证请求中提供的用户名是否唯一且不存在于数据库中。

我已经为此创建了自定义注解（UniqueUser.java）和自定义验证器（UniqueUserValidator.java）。

  1. public class User {
  2.     @NotNull
  3.     @UniqueUser
  4.     private String username;
  6.     @NotNull
  7.     private String password;
  9.     @NotNull
  10.     @Email
  11.     private String email;
  13.     @NotNull
  14.     private String phone;
  15. }

UniqueUser.java

  1. @Target({TYPE, ANNOTATION_TYPE})
  2. @Retention(RUNTIME)
  3. @Constraint(validatedBy = UniqueUserValidator.class)
  4. @Documented
  5. public @interface UniqueUser {
  6.     String message() default "User id already exists";
  7.     Class<?>[] groups() default {};
  8.     Class<? extends Payload>[] payload() default {};
  9. }

UniqueUserValidator.java

  1. public class UniqueUserValidator implements ConstraintValidator<UniqueUser, Object> {
  2.     @Autowired
  3.     UserRepository userRepository;
  5.     @Override
  6.     public boolean isValid(String userName, final ConstraintValidatorContext context) {
  7.         boolean isValidUser = false;
  8.         if (userName != null && !userName.isEmpty()) {
  9.             Optional<User> user = userRepository.findByUserId(userName);
  10.             isValidUser = !user.isPresent();
  11.         }
  12.         return isValidUser;
  13.     }
  14. }

在上述代码中，即使用户名字段为null，唯一用户验证也会被调用，并显示“用户名已存在”错误消息。我希望只有在用户名具有某些值时才调用自定义验证器。是否有可能避免这种调用。

我可以通过修改下面的方法来修复错误，如果用户名为null，则返回true，但我想避免这种不必要的调用。

  1. public class UniqueUserValidator implements ConstraintValidator<UniqueUser, Object> {
  2.     @Autowired
  3.     UserRepository userRepository;
  5.     @Override
  6.     public boolean isValid(String userName, final ConstraintValidatorContext context) {
  7.         boolean isValidUser = false;
  8.         if (userName != null && !userName.isEmpty()) {
  9.             Optional<User> user = userRepository.findByUserId(userName);
  10.             isValidUser = !user.isPresent();
  11.         } else {
  12.             isValidUser = true;
  13.         }
  14.         return isValidUser;
  15.     }
  16. }
英文:

I am working on javax validation API in Spring Boot Application. I have a User bean and i have to validate that username given in request is unique and doesn't exist into Database.

I have created custom annotation (UniqueUser.java) and custom Validator(UniqueUserValidator.java) for this requirement.

  1. public class User  {
  2.     @NotNull
  3.     @UniqueUser
  4.     private String username;
  6.     @NotNull
  7.     private String password;
  9.     @NotNull
  10.     @Email
  11.     private String email;
  13.     @NotNull
  14.     private String phone;
  15. }

UniqueUser.java

  1. @Target({TYPE, ANNOTATION_TYPE})
  2. @Retention(RUNTIME)
  3. @Constraint(validatedBy = UniqueUserValidator.class)
  4. @Documented
  5. public @interface NameMatch
  6. {
  7.     String message() default &quot;User id already exists&quot;;
  9.     Class&lt;?&gt;[] groups() default {};
  11.     Class&lt;? extends Payload&gt;[] payload() default {};
  12. }

UniqueUserValidator.java

  1. public class UniqueUserValidator implements ConstraintValidator&lt;NameMatch, Object&gt;
  2. {
  3.     @Autowired
  4.     UserRepository userRepository;
  5.    
  6.     @Override
  7.     public boolean isValid(String userName, final ConstraintValidatorContext context)
  8.     {
  9.         boolean isValidUser = false;
  10.         if(userName!=null &amp;&amp; !userName.isEmpty()) {
  11.         Optional&lt;User&gt; user= userRepository.findByUserId(userName);
  12.            isValidUser = !user.isPresent(); 
  13.         }
  14.         return isValidUser;
  15.     }
  16. }

In above code, the unique user validation get called for username field even if the field is null and shows Username already exists error message. I want the custom validator to get called only when username has some value. Is it possible to avoid this call.

I can fix the error by modifying the below method and returning true if username is null, but i want't to avoid this unnecessary call.

  1. public class UniqueUserValidator implements ConstraintValidator&lt;NameMatch, Object&gt;
  2. {
  3.     @Autowired
  4.     UserRepository userRepository;
  5.    
  6.     @Override
  7.     public boolean isValid(String userName, final ConstraintValidatorContext context)
  8.     {
  9.         boolean isValidUser = false;
  10.         if(userName!=null &amp;&amp; !userName.isEmpty()) {
  11.         Optional&lt;User&gt; user= userRepository.findByUserId(userName);
  12.            isValidUser = !user.isPresent(); 
  13.         } else {
  14.            isValidUser = true; 
  15.         }
  16.         return isValidUser;
  17.     }
  18. }

答案1

得分: 1

我认为您要寻找的是分组约束；

> 分组允许您在验证期间限制应用的约束集。验证组的一个用例是 UI 向导，在每个步骤中只需要验证指定的一部分约束。目标组以 var-arg 参数的形式传递给适当的验证方法。

在您的情况下，应该是这样的：

  1. @GroupSequence({ FirstConstaint.class, SecondConstaint.class })
  2. public class User  {
  3.     @NotNull(groups = FirstConstaint.class)
  4.     @UniqueUser(groups = SecondConstaint.class)
  5.     private String username;
  7.     // 其他字段
  8. }
  10. interface FirstConstaint {
  11. }
  13. interface SecondConstaint {
  14. }

这样，它只会在字段不为空时检查 @UniqueUser，否则，它将返回 @NotNull 验证的消息。

另外，如 @User 所说，您还可以将这些检查用于服务层 ^^

英文:

I think what you are looking for is Grouping constraints;

> Groups allow you to restrict the set of constraints applied during
> validation. One use case for validation groups are UI wizards where in
> each step only a specified subset of constraints should get validated.
> The groups targeted are passed as var-arg parameters to the
> appropriate validate method.

In your case it should look like this:

  1. @GroupSequence({ FirstConstaint.class, SecondConstaint.class })
  2. public class User  {
  3.     @NotNull(groups = FirstConstaint.class)
  4.     @UniqueUser(groups = SecondConstaint.class)
  5.     private String username;
  7.     // the rest of your fields
  8. }
  10. interface FirstConstaint {
  11. }
  13. interface SecondConstaint {
  14. }

This way, it will check @UniqueUser only if the field is not null, otherwise, it will return the message of @NotNull validation.

Otherwise like @User said you can use this checks in service layer ^^

huangapple
  • 本文由 发表于 2020年7月26日 22:18:52
  • 转载请务必保留本文链接：https://go.coder-hub.com/63101373.html
  • hibernate-validator
  • java
  • spring-boot
  • validation
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