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How to specify dependent choices for action parameters

Sometimes there is a dependency between the value of one parameter and the set of values to another. For example, if selecting a particular category, then this implies a set of subcategories belonging to that category. Or, if selecting a particular country, then this implies a set of states/counties within that country.

To specify such a dependency, the choicesNActionName() can be overloaded with the N-1 preceding parameters.

The syntax is:

public Collection<ParameterType> choicesNActionName(arg0, arg1, ..., argN-1)

where N indicates the 0-based parameter number. Any subtype of Collection may also be used.

For example:

public class Book {
    public void describeAndCategorize(
            @Named("Description") String description
            Genre genre,
            Subgenre subgenre) {
    public Collection<Subgenre> choices2Categorize(
           String description,
           Genre genre) {
        return genre.getSubgenres();

NOTE: at this writing this capability does not exist for properties that have dependencies. Instead, make the properties read-only (using @Disabled) and provide an action to update them instead.