Question

I am using f:viewparam to capture GET request params to a JSF page.

<f:metadata>
    <f:viewParam name="id" value="#{mediaGroupController.mediaGroupId}"/>
    <f:viewParam name="type" value="#{mediaGroupController.type}"/>
    <f:viewParam name="limit" value="#{mediaGroupController.limit}" converter="javax.faces.Integer" >
    <f:validateLongRange minimum="0"/>
    </f:viewParam>
</f:metadata>

This works OK if I enter valid parameters for all, like ?id=1&type=foo&limit=10. However, if one of the params is invalid, for example, ?id=1&type=foo&limit=bar, valid params like id and type are also ignored.

I would like to only ignore the limit parameter in such a case. How can I achieve that?

Answer 1

Create a custom converter which don’t throw a ConverterException, but just returns null when the conversion fails.

E.g.

<f:viewParam name="limit" value="#{mediaGroupController.limit}" converter="limitConverter">

with

@FacesConverter("limitConverter")
public class LimitConverter {

    @Override
    public Object getAsString(FacesContext context, UIComponent component, Object value) {
        return (value != null) ? String.valueOf(value) : null;
    }

    @Override
    public Object getAsObject(FacesContext context, UIComponent component, String value) {
        return (value != null && value.matches("\\d+") ? Integer.valueOf(value) : null;
    }

}