失去查看页面参数 [英] lose view page parameter
问题描述
我有页面my.xhtml:
i have page my.xhtml:
<f:metadata>
<f:viewParam name="id"/>
</f:metadata>
...
<h:form>
Current id is: "#{id}"
<h:commandButton action="#{bean.doSomething}" value="Do some logic..">
<f:param name="id" value="#{id}"/>
</h:commandButton>
</h:form>
和Bean.java:
and Bean.java:
@ManagedBean
@ViewScoped
public class Bean {
....
public void doSomething(){
//do some logick, don't use id parameter
}
}
当我第一次进入id = 10的页面时，可以在页面Current id is: "10".上看到.
当我单击按钮时，页面将重新加载，并且可以再次在页面Current id is: "10".上看到.
When I get to page first time with id=10 I can see on page Current id is: "10"..
When I click on button page is reload and I can see on page Current id is: "10". again.
但是当我第三次单击按钮时，我可以在页面Current id is: "".上看到，我丢失了id参数，我不明白为什么?
But when I click on button third time I can see on page Current id is: ""., i lose id parameter and I don't understand why?
我知道我可以通过在bean中保存参数值来做到这一点
(通过添加到f:viewParam:
I know I can do this with save parameter value in bean
(by add to f:viewParam:
<f:metadata>
<f:viewParam name="id" value="#{bean.value}/>
</f:metadata>
)，但是我可以在不将参数值保存到bean中的情况下执行此操作吗?
), but can I do this without save parameter value in bean?
推荐答案
h:button适用于f:param，但h:commandButton无效.在这种情况下，最好的方法是在解释最后一个参数时将view参数绑定到bean属性.只要调用void动作方法，@ViewScoped bean就会保留其状态.
h:button works with f:param but h:commandButton does not. In this case, your best is to bind the view parameter to a bean property as you explain the last. The @ViewScoped bean will retain its state as long as you call void action methods.
您也可以将它作为参数传递给action方法(有多种方法可以执行此操作)，但这对于与该值无关的方法没有意义.
You could also pass it as a parameter to the action method (there are several ways to do that), but this doesn't make sense for a method which has nothing to do with that value.
另请参见:
- Passing parameters to action methods in JSF
- Communication in JSF
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