TemplateContextLineService.java

/**
 * Axelor Business Solutions
 *
 * Copyright (C) 2016 Axelor (<http://axelor.com>).
 *
 * This program is free software: you can redistribute it and/or  modify
 * it under the terms of the GNU Affero General Public License, version 3,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.axelor.apps.base.service.template;

import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.persistence.TypedQuery;

import com.axelor.apps.base.db.TemplateContextLine;
import com.axelor.db.JPA;
import com.axelor.db.Model;
import com.axelor.meta.db.MetaModel;
import com.axelor.meta.db.repo.MetaModelRepository;
import com.google.common.base.Strings;
import com.axelor.inject.Beans;

public class TemplateContextLineService {

	public Object evaluate(TemplateContextLine line, Model bean) {
		
		String query = line.getQuery();
		if(Strings.isNullOrEmpty(query)) {
			return null;
		}
		
		return this.evaluate(query, bean);
	}
	
	public Object evaluate(String query, Model bean) {
		try {
			Class<?> klass = this.extractClass(query);
			StringBuilder sb = new StringBuilder(query);
			int n = 0, i = sb.indexOf("?");
			while (i > -1) {
				sb.replace(i, i + 1, "?" + (++n));
				i = sb.indexOf("?", i + 1);
			}

			TypedQuery<?> querie = JPA.em().createQuery(sb.toString(), klass);
			for (int j = 1; j <= n; j++) {
				querie.setParameter(n, bean);
			}
			List<?> list = querie.getResultList();
			if(list != null && !list.isEmpty() && list.size() == 1) {
				return list.get(0);
			}
			else {
				return list;
			}
			
		}
		catch(Exception ex) {
			ex.printStackTrace();
		}
		return null;
	}

	private Class<?> extractClass(String query) {
		Pattern pattern = Pattern.compile("(from|FROM)(\\s*)(.+?)(\\s)");
		Matcher matcher = pattern.matcher(query);
		
		String klassName = "";
		if (matcher.find()) {
			klassName = matcher.group(3).trim();
		}
		
		MetaModel model = Beans.get(MetaModelRepository.class).findByName(klassName);
		try {
			return Class.forName(model.getFullName());
		}
		catch(Exception ex){
		}
		return null;
	}
	
	
}