在EL中嵌套变量 [英] Nesting variables in EL

问题描述

是否可以使用FacesContext或其他诸如request，session等隐式对象在EL中嵌套下面的变量调用?这当然是行不通的.我收到此错误

Is it possible to nest variable calls like below in EL using FacesContext or other implicit objects like request, session, etc.? This of course is not working. I get this error

错误解析:#{myBean.myMethod(#{FacesContext.getCurrentInstance().getViewRoot().getViewId()})}

Error Parsing: #{myBean.myMethod(#{FacesContext.getCurrentInstance().getViewRoot().getViewId() })}

为此尝试

<ui:include src="#{myBean.myMethod(#{FacesContext.getCurrentInstance().getViewRoot().getViewId() })}">

推荐答案

这确实是无效的EL语法. #{}的嵌套是不允许的.只需将整个表达式放在相同的#{}中.另外，#{FacesContext}在Facelets的EL范围中不存在，它是#{facesContext}，并且已经是当前实例.此外，如果已经是getter方法，则不必用括号指定整个方法名称.

This is indeed invalid EL syntax. Nesting of #{} is disallowed. Just put the whole expression inside the same #{}. Plus, the #{FacesContext} doesn't exist in Facelets' EL scope, it's #{facesContext} and it's already the current instance. Further, you don't necessarily need to specify the entire method name with parentheses if it are getter method already.

所以，这应该做

<ui:include src="#{myBean.myMethod(facesContext.viewRoot.viewId)}">

(请注意，这仍然需要具有Servlet 3.0/EL 2.2支持的目标容器)

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