Dynamic choice of bean in EL

Question

Is there a way to specify a managed bean used in EL at runtime and not design time? E.g. actionListener=\"#{myBean.method}\" such that myBean part

Answer 1

If your question refers to generating a set of pages for a number of subclasses with common elements you can also use page composition to achieve this.

For example if Resident and NonResident are managed beans for subclasses of Person:

eg. in 'non-resident.xhtml'

<ui:define name="body">
    <ui:param name="Controller" value="#{NonResident}"/>
    <ui:include src="anyone.xhtml"/>
</ui:define>

and in 'resident.xhtml'

<ui:define name="body">
    <ui:param name="Controller" value="#{Resident}"/>
    <ui:include src="anyone.xhtml"/>
</ui:define>

then 'anyone.xhtml' can define the common elements using 'Controller' for the bean name.

This approach also enables you to eliminate duplicate page definition.

Answer 2

If you know the bean scope beforehand and the bean is already created beforehand, then yes, it's possible using the following syntax:

actionListener="#{requestScope[beanName].method}"

where #{requestScope} represents the request scope map (same maps are available for view, session and application scopes) and #{beanName} represents the variable holding the managed bean name.

If you don't know the bean scope beforehand and/or when the bean isn't created beforehand, then you'd need to create an utility EL function which does an Application#evaluateExpressionGet(), so that it can be used something like as follows:

actionListener="#{util:getBean(beanName).method}"