JSF根据验证从bean更新值的正确方法 [英] JSF correct way to update a value from a bean depending on validation

问题描述

我有一个与页面关联的bucking bean，我想根据验证是否成功来更改其值.

I have a bucking bean associated to a page and I want to change its value depending on whether a validation failed or succeeded.

@ManagedBean(name = "testBean")
@ViewScoped()
public class TestBean implements Serializable {

String value="";
int number;

  /*getters-setters*/
}

一个验证器，用于检查数字是否为正

a validator that checks if the number is positive

@FacesValidator("Validator")
public class NumValidator implements Validator{



    @Override
    public void validate(FacesContext context, UIComponent component,
            Object value) throws ValidatorException {

        int num=(Integer)value;
        if(num<0){
            FacesMessage msg = 
                new FacesMessage(The number is negative");
            msg.setSeverity(FacesMessage.SEVERITY_ERROR);
            throw new ValidatorException(msg);
           }


    }
}

和一个xhmtl页面:

and a xhmtl page:

<h:form>
<h:inputText id="number" value="#{testBean.number}" required="true"
                    requiredMessage="Is">
                    <f:validator validatorId="Validator" />
                    <f:ajax event="blur" render="msg" />
                </h:inputText>
                <h:message id="msg" for="number"/>
</h:form>

并且我希望Bean中的String不管值是value ="negative"或value ="positive".该怎么办?

And I want the String in the bean to be value="negative" or value="positive" whether the occastion. How can this be done?

推荐答案

您的具体功能要求可归结为:

Your concrete functional requirement appears to boil down to:

当发生验证错误时，如何更改< h:inputText> 的样式类?

How do I change the style class of <h:inputText> when it has a validation error?

在这种情况下，只需检查EL中的 UIInput#isValid() .当前的UI组件仅可通过隐式EL对象获取 #{component} .

In that case, just check UIInput#isValid() in EL. The current UI component is just available by implicit EL object #{component}.

<h:inputText ... styleClass="#{component.valid ? 'positive' : 'negative'}">
    <f:ajax ... render="@this msg" />
</h:inputText>

请注意，我在 render 中添加了 @this ，否则该组件本身将不会被更新.

Note that I added @this to the render, otherwise the component itself wouldn't be updated.

您不应使用特定于视图的属性(例如CSS类)来污染模型.您应该尽量将它们放在视图侧.最终将得到更多自然"的解决方案.

You shouldn't be polluting the model with view-specific properties such as CSS classes. You should try to keep them in the view side as much as possible. This will end up in more "natural" solutions.

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