how to write Hibernate Criteria to take nested objects by Projection List?

Question

I want to take Nested object values in Hibernate Projection List. I having Pojo \'Charge\' and \'Tariff\' class with OneToMany and ManyToOne relations.

My sample cod

Answer 1

The AliasToBeanNestedResultTransformer does not handle Multilevel Nested DTO's. Meaning, you won't be able to do company.employee.location each in its own DTO.

Here is a Transformer I wrote that handles Multilevel Nested DTOs. You may used it by calling:

criteria.setResultTransformer( AliasToBeanNestedMultiLevelResultTransformer(mappingBean));

Hope it helps.

public class AliasToBeanNestedMultiLevelResultTransformer extends AliasedTupleSubsetResultTransformer {

private static final long serialVersionUID = -8047276133980128266L;

public boolean isTransformedValueATupleElement(String[] aliases, int tupleLength) {
    return false;
}

private boolean initialized;
private Class resultClass;
private Map> clazzMap = new HashMap<>();
private Map settersMap = new HashMap<>();

public AliasToBeanNestedMultiLevelResultTransformer(Class resultClass) {
    this.resultClass = resultClass;
}

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

    Map nestedObjectsMap = new HashMap<>();

    Object result;
    try {
        result = resultClass.newInstance();

        if (!initialized){
            initialized = true;
            initialize(aliases);
        }

        for (int a=0;a0){
                String basePath = alias.substring(0, index);
                baseObject = nestedObjectsMap.get(basePath);
                if (baseObject == null){
                    baseObject = clazzMap.get(basePath).newInstance();
                    nestedObjectsMap.put(basePath, baseObject);
                }
            }

            settersMap.get(alias).set(baseObject, tuple,null);

        }

        for (Entry entry:nestedObjectsMap.entrySet()){
            Setter setter = settersMap.get(entry.getKey());
            if (entry.getKey().contains(".")){

                int index = entry.getKey().lastIndexOf(".");
                String basePath = entry.getKey().substring(0, index);
                Object obj = nestedObjectsMap.get(basePath);

                setter.set(obj, entry.getValue(), null);
            }
            else{
                setter.set(result, entry.getValue(), null);
            }
        }

    }catch ( InstantiationException | IllegalAccessException e) {
        throw new HibernateException( "Could not instantiate resultclass: " + resultClass.getName() );
    }

    return result;
}


private void initialize(String[] aliases) {

    PropertyAccessor propertyAccessor = new ChainedPropertyAccessor(
            new PropertyAccessor[] {
                    PropertyAccessorFactory.getPropertyAccessor( resultClass, null ),
                    PropertyAccessorFactory.getPropertyAccessor( "field" )
            }
    );

    for (int a=0;a baseClass = resultClass;

        if (alias.contains(".")){

            String[] split = alias.split("\\.");

            StringBuffer res = new StringBuffer();

            for (int i=0;i0) res.append(".");

                String item = split[i];
                res.append(item);

                String resString = res.toString();

                if (i==split.length-1){
                    clazzMap.put(resString,baseClass);
                    settersMap.put(resString, propertyAccessor.getSetter(baseClass, item));
                    break;
                }

                Class clazz = clazzMap.get(resString);
                if (clazz==null){
                    clazz = propertyAccessor.getGetter(baseClass,item).getReturnType();
                    settersMap.put(resString, propertyAccessor.getSetter(baseClass, item));
                    clazzMap.put(resString,clazz);
                }
                baseClass = clazz;
            }
        }
        else{
            clazzMap.put(alias, resultClass);
            settersMap.put(alias, propertyAccessor.getSetter(resultClass, alias));
        }

    }

}

}