No access to nested property in managed bean within p:columns - jsf

Question

I have following two simple POJOs:
class Person {
String name
Address address;
//and of course the getter/setter for the attributes
}
class Address {
String city;
//also getter/setter for this attribute
}
And a backing bean:
#ManagedBean
#RequestScoped
class PersonController {
private List persons;
private List<String> columns = Arrays.toList("name", "address.city");
//of course getter/setter
}
Now I want to create a dataTable.
<p:dataTable var="person" value="#{personController.persons}" columnIndexVar="index">
<p:columns var="column" value="#{personController.columns}">
<h:outputText value="#{person[column]}"/>
<p:columms>
</p:dataTable>
When I execute this I get a ServletException:
The class Person does not have the property 'address.city'.
But if a try to access the property city like this within p:columns:
<h:outputText value="#{person.address.city}"/>
Everything is fine.
Why I can not access a nested property like that #{person['address.city']}? And how can I access it within p:columns?

Answer 1

Nested bean properties in a brace notation string expression like #{person['address.city']} is by default not supported. You basically need a #{person['address']['city']}.
You need a custom ELResolver here. Easiest is to extend the existing BeanELResolver.
Here's a kickoff example:
public class ExtendedBeanELResolver extends BeanELResolver {
#Override
public Object getValue(ELContext context, Object base, Object property)
throws NullPointerException, PropertyNotFoundException, ELException
{
if (property == null || base == null || base instanceof ResourceBundle || base instanceof Map || base instanceof Collection) {
return null;
}
String propertyString = property.toString();
if (propertyString.contains(".")) {
Object value = base;
for (String propertyPart : propertyString.split("\\.")) {
value = super.getValue(context, value, propertyPart);
}
return value;
}
else {
return super.getValue(context, base, property);
}
}
}
To get it to run, register it as follows in faces-config.xml:
<application>
<el-resolver>com.example.ExtendedBeanELResolver</el-resolver>
</application>

Answer 2

In addition to #BalusC answer I had to add a check for PrimeResourceHandler. Otherwise all resolvements of #{resource...} like #{resource['primefaces:spacer/dot_clear.gif']} inside the primefaces.css failed and the output stream of the parsed CSS file gets corrupted.
public class ExtendedBeanELResolver extends BeanELResolver {
private static final String PRIMEFACES_RESOURCE_PREFIX = "primefaces:";
#Override
public Object getValue(ELContext context, Object base, Object property) throws NullPointerException,
PropertyNotFoundException, ELException {
if (property == null || base == null || base instanceof ResourceBundle || base instanceof Map
|| base instanceof Collection || base instanceof PrimeResourceHandler) {
return null;
}
String propertyString = property.toString();
if (!propertyString.startsWith(PRIMEFACES_RESOURCE_PREFIX) && propertyString.contains(".")) {
Object value = base;
for (String propertyPart : propertyString.split("\\.")) {
value = super.getValue(context, value, propertyPart);
}
return value;
} else {
return super.getValue(context, base, property);
}
}
}