Embedding a link (or other html) in a JSF message - jsf

Question

I want to embed a link in a JSF message, is this possible?
When I try it, the rendered html of the h:messages tag escapes the html characters. I tried setting the escape attribute of the h:messages tag to false, but that didn't help.

Answer 1

Unfortunately, this is not possible in the standard JSF implementation. The component and the renderer doesn't officially support this attribute. You can however homegrow a renderer which handles this.
Since this is a pretty common requirement/wish, I thought to take a look what's all possible.
First some background information: JSF by default uses ResponseWriter#writeText() to write the tag body, which escapes HTML by default. We'd like to let it use ResponseWriter#write() instead like as with <h:outputText escape="false" />. We'd like to extend the MessagesRenderer of the standard JSF implementation and override the encodeEnd() method accordingly. But since the MessagesRenderer#encodeEnd() contains pretty a lot of code (~180 lines) which we prefer not to copypaste to just change one or two lines after all, I found it better to replace the ResponseWriter with a custom implementation with help of ResponseWriterWrapper wherein the writeText() is been overriden to handle the escaping.
So, I ended up with this:
package com.example;
import java.io.IOException;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.context.ResponseWriter;
import javax.faces.context.ResponseWriterWrapper;
import javax.faces.render.FacesRenderer;
import com.sun.faces.renderkit.html_basic.MessagesRenderer;
#FacesRenderer(componentFamily="javax.faces.Messages", rendererType="javax.faces.Messages")
public class EscapableMessagesRenderer extends MessagesRenderer {
#Override
public void encodeEnd(FacesContext context, UIComponent component) throws IOException {
final ResponseWriter originalResponseWriter = context.getResponseWriter();
try {
context.setResponseWriter(new ResponseWriterWrapper() {
#Override
public ResponseWriter getWrapped() {
return originalResponseWriter;
}
#Override
public void writeText(Object text, UIComponent component, String property) throws IOException {
String string = String.valueOf(text);
String escape = (String) component.getAttributes().get("escape");
if (escape != null && !Boolean.valueOf(escape)) {
super.write(string);
} else {
super.writeText(string, component, property);
}
}
});
super.encodeEnd(context, component); // Now, render it!
} finally {
context.setResponseWriter(originalResponseWriter); // Restore original writer.
}
}
}
In spite of the #FacesRenderer annotation, it get overriden by the default MessagesRenderer implementation. I suspect here a bug, so I reported issue 1748. To get it to work anyway, we have to fall back to the faces-config.xml:
<render-kit>
<renderer>
<component-family>javax.faces.Messages</component-family>
<renderer-type>javax.faces.Messages</renderer-type>
<renderer-class>com.example.EscapableMessagesRenderer</renderer-class>
</renderer>
</render-kit>
Then, to trigger it, just do:
<h:messages escape="false" />
And it works! :)
Note: the above affects <h:messages> only. To do the same for <h:message>, just do the same, but replace anywhere "Messages" by "Message" (component family, renderer type and classnames).

Answer 2

The escape="false" attributed you need is provided by the OmniFaces <o:messages> component. The OmniFaces utility library is available for JSF 2.
I posted this solution mentioned by #BalusC's comment as an answer since this is the most straightforward solution.