PostgreSQLIntervalFunction.java

package fr.openwide.core.jpa.hibernate.dialect.function;

import java.util.List;

import org.hibernate.QueryException;
import org.hibernate.dialect.function.SQLFunction;
import org.hibernate.engine.spi.Mapping;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.type.Type;

/**
 * Est utilisée pour permettre d'utiliser des intervals dans les requêtes QueryDSL.
 * 
 * Typiquement via :
 * <pre>
 * query.from(QUser.user).where(BooleanTemplate.create("{0} - {2} * interval({1}) < now()", QUser.user.creationDate, "1 day", 4)); 
 * </pre>
 */
public class PostgreSQLIntervalFunction implements SQLFunction {

	@Override
	public boolean hasArguments() {
		return true;
	}

	@Override
	public boolean hasParenthesesIfNoArguments() {
		return true;
	}

	@Override
	public Type getReturnType(Type firstArgumentType, Mapping mapping) throws QueryException {
		return null;
	}

	@SuppressWarnings("rawtypes")
	@Override
	public String render(Type firstArgumentType, List args, SessionFactoryImplementor factory)
			throws QueryException {
		if (args.size() != 1) {
			throw new QueryException("interval() requires one argument");
		}
		
		return args.get(0) + "::interval";
	}

}