GroupExpressionResultTransformer.java

package fr.openwide.core.jpa.querydsl.group;

import com.mysema.commons.lang.CloseableIterator;
import com.querydsl.core.FetchableQuery;
import com.querydsl.core.ResultTransformer;
import com.querydsl.core.group.GroupCollector;
import com.querydsl.core.group.GroupExpression;

class GroupExpressionResultTransformer<T, R> implements ResultTransformer<R> {

	private final GroupExpression<T, R> groupExpression;

	public GroupExpressionResultTransformer(GroupExpression<T, R> groupExpression) {
		super();
		this.groupExpression = groupExpression;
	}

	@Override
	public R transform(FetchableQuery<?, ?> query) {
		CloseableIterator<T> iter = query.select(groupExpression.getExpression()).iterate();
		GroupCollector<T, R> collector = groupExpression.createGroupCollector();
		try {
			while (iter.hasNext()) {
				T collectable = iter.next();
				collector.add(collectable);
			}
		} finally {
			iter.close();
		}
		return collector.get();
	}
}