How to determine if an Entity has a NamedQuery

Question

Again, posting and answering a question for the benefit of others based on a problem I had the other day. Hopefully this saves someone a bit of time. I was a little surprised this wasn't built into JPA's EntityManager.

How can I determine if an Entity has a NamedQuery annotation with a specific name?

I need to determine if an Entity has a particular @NamedQuery before I try executing it.

Answer 1

When annotations are nested, you can get the properties of the annotation to get it's children. In the case of @NamedQueries, it's .value().

public boolean hasNamedQuery(Class<?> clazz, String nameOfQuery) {
    boolean foundQueryByName = false;
    NamedQueries namedQueries = clazz.getAnnotation(NamedQueries.class);
    if (namedQueries != null && namedQueries.value() != null) {
        NamedQuery[] values = namedQueries.value();
        for (int i = 0; i < values.length && !foundQueryByName; i++) {
            foundQueryByName |= (nameOfQuery.equals(values[i].name()));
        }
    }
    return foundQueryByName;
}