使用EJB服务调用进行验证，可以使用JSF验证器还是JSR303 bean验证？ [英] Validation with an EJB service call, possible with JSF validator or JSR303 bean validation?

问题描述

我想使用select验证我的用户名。如果用户名已经
存在于数据库中，验证失败。

我发现了一些这样的标注注释，例如：

  @Size（min = 2，max = 5）
 private String name; 
  

我没有找到这样的注释解决方案：

  try {
 dao.findUserByUserName（userName）; 
 
 message = new FacesMessage（Invalid username！，Username Validation Error）; 
 message.setDetail（Username already exists！）; 
 message.setSeverity（FacesMessage.SEVERITY_ERROR）; 
 
 throw new ValidatorException（message）; 
} catch（NoSuchUserException e）{} 
  

我必须使用自定义验证器有没有注释？

解决方案

我必须使用自定义验证器有没有注释？

可以两种方式完成。

如果有自定义的JSF验证器，您只需要了解一个EJB不能注入到一个 @FacesValidator 。您基本上有3个选项：

1. 从JNDI手动获取


2. @ManagedBean 而不是 @FacesValidator


3. 或安装OmniFaces，为 @EJB 和 @Inject 在中添加透明支持@FacesValidator

最终，你可以这样结束，假设你去 c code code code $ c
public class UsernameValidator implements Validator {

@EJB
private UserService service;

public void validate（FacesContext context，UIComponent component，Object submittedValue）throws ValidatorException {
if（submittedValue == null）{
return; //让required =true句柄。
}

String username =（String）submittedValue;

if（service.exist（username）{
throw new ValidatorException（new FacesMessage（Username already in use，choose another））;
}
}

}

使用如下：

 < h：inputText ... validator =＃{usernameValidator}/> 
  pre> 
 
 
在JSR303 bean验证的情况下，您需要创建一个定制 @Constraint 注释使用自定义 ConstraintValidator  。您需要确保至少使用CDI 1.1，否则您无法在一个 ConstraintValidator ，您需要手动从 initialize（）方法中从JNDI抓取它。你不能通过使它成为一个受管理的bean来解决它，甚至OmniFaces对此没有任何魔力。
 
 
 
例如
  @Constraint（validatedBy = UsernameValidator.class）
 @Documented 
 @Retention（RetentionPolicy.RUNTIME）
 @Target（{ElementType.FIELD ，ElementType.METHOD，ElementType.ANNOTATION_TYPE}）
 public @interface用户名{
 String message（）默认用户名已在使用中，选择另一个; 
 Class<？> [] groups（）default {}; 
 Class<？扩展有效载荷> [] payload（）default {}; 
} 
  
与
  public class UsernameValidator implements ConstraintValidator< Username，String> {
 
 @EJB 
私人UserService服务; 
 
 @Override 
 public void initialize（Username constraintAnnotation）{
 //如果没有在CDI 1.1上，那么您需要从JNDI手动抓取EJB。 
} 
 
覆盖
 public boolean isValid（String username，ConstraintValidatorContext context）{
 return！service.exist（username）; 
} 
 
} 
  
和模型
  @Username 
 private String username; 
  
 
i want to validate my username using a select. if the username already
is present in the database, validation fails.

i found some annotations for primefaces like this for example:
@Size(min=2,max=5)  
private String name; 
i didnt found a annotation solution for something like this:
try {
    dao.findUserByUserName(userName);

    message = new FacesMessage ("Invalid username!", "Username Validation Error");
    message.setDetail("Username already exists!");
    message.setSeverity(FacesMessage.SEVERITY_ERROR);

    throw new ValidatorException(message);
} catch (NoSuchUserException e) {}
Do i have to use a custom validator or are there annotations for it?
解决方案

  
Do i have to use a custom validator or are there annotations for it?
It can be done both ways. 

In case of a custom JSF validator, you only need to understand that an EJB cannot be injected in a @FacesValidator. You've basically 3 options:

manually obtain it from JNDI
or, make it a @ManagedBean instead of @FacesValidator
or, install OmniFaces which adds transparent support for @EJB and @Inject in @FacesValidator
Ultimately, you can end up like this, assuming that you went for the @ManagedBean approach:
@ManagedBean
@RequestScoped
public class UsernameValidator implements Validator {

    @EJB
    private UserService service;

    public void validate(FacesContext context, UIComponent component, Object submittedValue) throws ValidatorException {
        if (submittedValue == null) {
            return; // Let required="true" handle.
        }

        String username = (String) submittedValue;

        if (service.exist(username) {
            throw new ValidatorException(new FacesMessage("Username already in use, choose another"));
        }
    }

}
Which is used as follows:
<h:inputText ... validator="#{usernameValidator}" />
In case of JSR303 bean validation, you'd need to create a custom @Constraint annotation along with a custom ConstraintValidator. You need to make sure that you're using at least CDI 1.1, otherwise you can't inject an EJB in a ConstraintValidator and you'd need to resort to manually grabbing it from JNDI in initialize() method. You can't solve it by making it a managed bean and even OmniFaces hasn't any magic for this.

E.g.
@Constraint(validatedBy = UsernameValidator.class)
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD, ElementType.METHOD, ElementType.ANNOTATION_TYPE})
public @interface Username {
    String message() default "Username already in use, choose another";
    Class<?>[] groups() default {};
    Class<? extends Payload>[] payload() default {};
}
with
public class UsernameValidator implements ConstraintValidator<Username, String> {

    @EJB
    private UserService service;

    @Override
    public void initialize(Username constraintAnnotation) {
        // If not on CDI 1.1 yet, then you need to manually grab EJB from JNDI here.
    }

    Override
    public boolean isValid(String username, ConstraintValidatorContext context) {
        return !service.exist(username);
    }

}
and in model
@Username
private String username;


                        
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