Complex Hibernate Projections

Question

I want to ask, it is possible that I create query projections and criterion for more than one level deep? I have 2 model classes:

@Entity  
@Table(name = \"p         


        

Answer 1

Thanks Sami Andoni. I was able to use your AliasToBeanNestedResultTransformer with a minor modification to suit my situation. What I found was that the nested transformer did not support the scenario where the field is in a super class so I enhanced it to look for fields up to 10 levels deep in the class inheritance hierarchy of the class you're projecting into:

    public Object transformTuple(Object[] tuple, String[] aliases) {

        ...


                if (alias.contains(".")) {
                    nestedAliases.add(alias);

                    String[] sp = alias.split("\\.");
                    String fieldName = sp[0];
                    String aliasName = sp[1];

                    Class subclass = getDeclaredFieldForClassOrSuperClasses(resultClass, fieldName, 1);
...
}

Where getDeclaredFieldForClassOrSuperClasses() is defined as follows:

private Class getDeclaredFieldForClassOrSuperClasses(Class resultClass, String fieldName, int level) throws NoSuchFieldException{
    Class result = null;
    try {
        result = resultClass.getDeclaredField(fieldName).getType();
    } catch (NoSuchFieldException e) {
        if (level <= 10){
        return getDeclaredFieldForClassOrSuperClasses(
                resultClass.getSuperclass(), fieldName, level++);
        } else {
            throw e;
        }
    }
    return result;
}

My Hibernate projection for this nested property looked like this:

Projections.projectionList().add( Property.forName("metadata.copyright").as("productMetadata.copyright"));

and the class I am projecting into looks like this:

public class ProductMetadata extends AbstractMetadata {
...
}

public abstract class AbstractMetadata {
...   
   protected String copyright;
...
}