How to invoke JSF backing bean method from link/non-faces-request - jsf-2

Question

The use case is calling a method on a JSF 2.x Backing Bean directly from a hyperlink (Non-Faces-Request). What is the best way to do this?
I imagine to do something like this:
The Link:
http://localhost/show.xhtml?id=30&backingbeanname=loaddata&method=load
The Backing Bean:
#Named (value = "loaddata")
public class DataLoader {
public void load(int id){ ... }
}

Answer 1

Use <f:viewParam> in the target view to set GET parameters as bean properties and use <f:event type="preRenderView"> to invoke an action on them.
In show.xhtml:
<f:metadata>
<f:viewParam name="id" value="#{bean.id}" required="true" />
<f:event type="preRenderView" listener="#{bean.load}" />
</f:metadata>
<h:message for="id" />
In managed bean:
private Integer id;
private Data data;
public void load() {
data = service.find(id);
}
Note that in the above example the URL http://localhost/show.xhtml?id=30 is sufficient. You can always set more parameters as bean properties and have one "God" bean which delegates everything, but that's after all likely clumsy.
Also note that you can just attach a Converter to the <f:viewParam> (like as you could do in <h:inputText>). The load() method is then most likely entirely superfluous.
<f:metadata>
<f:viewParam name="id" value="#{bean.data}"
converter="dataConverter" converterMessage="Bad request. Unknown data."
required="true" requiredMessage="Bad request. Please use a link from within the system." />
</f:metadata>
<h:message for="id" />
See also:
Communication in JSF 2 - Processing GET request parameters
What can <f:metadata>, <f:viewParam> and <f:viewAction> be used for?