001/**
002 *   GRANITE DATA SERVICES
003 *   Copyright (C) 2006-2013 GRANITE DATA SERVICES S.A.S.
004 *
005 *   This file is part of the Granite Data Services Platform.
006 *
007 *   Granite Data Services is free software; you can redistribute it and/or
008 *   modify it under the terms of the GNU Lesser General Public
009 *   License as published by the Free Software Foundation; either
010 *   version 2.1 of the License, or (at your option) any later version.
011 *
012 *   Granite Data Services is distributed in the hope that it will be useful,
013 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
014 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
015 *   General Public License for more details.
016 *
017 *   You should have received a copy of the GNU Lesser General Public
018 *   License along with this library; if not, write to the Free Software
019 *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
020 *   USA, or see <http://www.gnu.org/licenses/>.
021 */
022package org.granite.tide.spring.data;
023
024import java.beans.BeanInfo;
025import java.beans.Introspector;
026import java.beans.PropertyDescriptor;
027import java.util.ArrayList;
028import java.util.List;
029
030import javax.persistence.criteria.CriteriaBuilder;
031import javax.persistence.criteria.CriteriaQuery;
032import javax.persistence.criteria.Path;
033import javax.persistence.criteria.Predicate;
034import javax.persistence.criteria.Root;
035import javax.persistence.metamodel.Attribute;
036import javax.persistence.metamodel.ManagedType;
037import javax.persistence.metamodel.Metamodel;
038
039import org.springframework.data.jpa.domain.Specification;
040
041public class FilterExampleSpecification<T> implements Specification<T> {
042        
043        private Metamodel metamodel;
044        private Object filter;
045        
046        private FilterExampleSpecification(Metamodel metamodel, Object filter) {
047                this.metamodel = metamodel;
048                this.filter = filter;
049        }
050        
051        public static <T> FilterExampleSpecification<T> byExample(Metamodel metamodel, Object filter) {
052                return new FilterExampleSpecification<T>(metamodel, filter);
053        }
054        
055        public Predicate toPredicate(Root<T> root, CriteriaQuery<?> query, CriteriaBuilder builder) {
056                List<Predicate> predicates = new ArrayList<Predicate>();
057                
058                applyAttributes(predicates, root, builder, metamodel.entity(filter.getClass()), filter);
059                
060                if (predicates.size() > 0)
061                        return builder.and(predicates.toArray(new Predicate[predicates.size()]));
062                
063                return null;
064        }
065        
066        private void applyAttributes(List<Predicate> predicates, Path<?> root, CriteriaBuilder builder, ManagedType<?> filterType, Object filter) {
067                // Query by example : the filter is of the same type as the entity
068                PropertyDescriptor[] pds = null;
069                try {
070                        // Query by bean filter
071                        BeanInfo info = Introspector.getBeanInfo(filter.getClass());
072                        pds = info.getPropertyDescriptors();
073                }
074                catch (Exception e) {
075                        throw new RuntimeException("Could not introspect filter bean", e);
076                }
077                
078                for (PropertyDescriptor pd : pds) {
079                        if (pd.getReadMethod().isAnnotationPresent(FilterMapping.class) && pd.getReadMethod().getAnnotation(FilterMapping.class).mode() == FilterMode.EXCLUDE)
080                                continue;
081                        
082                        Attribute<?, ?> attribute = filterType.getAttribute(pd.getName());
083                        if (attribute == null)
084                                continue;
085                        
086                        if (attribute.getPersistentAttributeType() == Attribute.PersistentAttributeType.EMBEDDED) {
087                                // Visit embedded elements recursively
088                                try {
089                                        Object embedded = pd.getReadMethod().invoke(filter);
090                                        if (embedded != null) {
091                                                ManagedType<?> embeddedType = metamodel.embeddable(attribute.getJavaType());
092                                                applyAttributes(predicates, root.get(pd.getName()), builder, embeddedType, embedded);
093                                        }
094                                }
095                                catch (Exception e) {
096                                        throw new RuntimeException("Could not get filter property " + pd.getName(), e);
097                                }
098                                
099                                continue;
100                        }
101                        
102                        if (pd.getWriteMethod() == null || attribute.getPersistentAttributeType() != Attribute.PersistentAttributeType.BASIC)
103                                continue;
104                        
105                        Object value = null;
106                        try {
107                                value = pd.getReadMethod().invoke(filter);
108                        }
109                        catch (Exception e) {
110                                throw new RuntimeException("Could not get filter property " + pd.getName(), e);
111                        }
112                        
113                        Predicate predicate = FilterSpecUtil.buildPredicate(root, builder, pd.getReadMethod().getReturnType(), pd.getName(), value);
114                        if (predicate != null)
115                                predicates.add(predicate);
116                }
117        }
118}