Hi
This is a simple example of using ComponentClassTransformWorker and also may
be used for graceful degradation for ajax in case javascript is disabled
All it does is convert a call
@XHR
Object onClick(){
//Processing ...
return zone.getBody();
}
to
Object onClick(){
//Processing
if(!request.isXHR()){
return null;
}else {
return zone.getBody();
}
}
Here is the code
Annotation
@Documented
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface XHR {
}
Worker
import org.apache.tapestry5.model.MutableComponentModel;
import org.apache.tapestry5.services.ClassTransformation;
import org.apache.tapestry5.services.ComponentClassTransformWorker;
import org.apache.tapestry5.services.ComponentMethodAdvice;
import org.apache.tapestry5.services.ComponentMethodInvocation;
import org.apache.tapestry5.services.Request;
import org.apache.tapestry5.services.TransformMethod;
import org.apache.tapestry5.services.TransformMethodSignature;
import com.google.code.tapestryaddons.XHR;
public class XHRWorker implements ComponentClassTransformWorker {
private Request request;
public XHRWorker(Request request){
this.request = request;
}
public void transform(ClassTransformation transformation,
MutableComponentModel model) {
for(final TransformMethod method:
transformation.matchMethodsWithAnnotation(XHR.class)){
TransformMethodSignature signature = method.getSignature();
if(!"void".equals(signature.getReturnType())){
method.addAdvice(new ComponentMethodAdvice(){
public void advise(ComponentMethodInvocation invocation) {
invocation.proceed();
Object result = invocation.getResult();
if(!request.isXHR()){
result = null;
}
invocation.overrideResult(result);
}
});
}
}
}
}
and obviously the contribution
public void contributeComponentClassTransformWorker(
OrderedConfiguration<ComponentClassTransformWorker> configuration){
configuration.addInstance("XHRWorker", XHRWorker.class);
}
A simple example
Template File
<?xml version="1.0" encoding="UTF-8"?>
<html xmlns:t='http://tapestry.apache.org/schema/tapestry_5_1_0.xsd'>
<t:eventLink t:zone='zone' t:id='click'>Ajax Link</t:eventLink>
<br/>
<t:zone t:id='zone'>Clicked ${count} times</t:zone>
</html>
and java file
import org.apache.tapestry5.annotations.InjectComponent;
import org.apache.tapestry5.annotations.Persist;
import org.apache.tapestry5.corelib.components.Zone;
import com.google.code.tapestryaddons.XHR;
public class XHRDemo {
@Persist
private int count;
@InjectComponent
private Zone zone;
@XHR
Object onClick(){
count++;
return zone.getBody();
}
public int getCount(){
return count;
}
}
