001 /*
002 GRANITE DATA SERVICES
003 Copyright (C) 2011 GRANITE DATA SERVICES S.A.S.
004
005 This file is part of Granite Data Services.
006
007 Granite Data Services is free software; you can redistribute it and/or modify
008 it under the terms of the GNU Library General Public License as published by
009 the Free Software Foundation; either version 2 of the License, or (at your
010 option) any later version.
011
012 Granite Data Services is distributed in the hope that it will be useful, but
013 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
014 FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License
015 for more details.
016
017 You should have received a copy of the GNU Library General Public License
018 along with this library; if not, see <http://www.gnu.org/licenses/>.
019 */
020
021 package org.granite.tide.spring.data;
022
023 import java.beans.BeanInfo;
024 import java.beans.Introspector;
025 import java.beans.PropertyDescriptor;
026 import java.util.ArrayList;
027 import java.util.List;
028
029 import javax.persistence.criteria.CriteriaBuilder;
030 import javax.persistence.criteria.CriteriaQuery;
031 import javax.persistence.criteria.Path;
032 import javax.persistence.criteria.Predicate;
033 import javax.persistence.criteria.Root;
034 import javax.persistence.metamodel.Attribute;
035 import javax.persistence.metamodel.ManagedType;
036 import javax.persistence.metamodel.Metamodel;
037
038 import org.springframework.data.jpa.domain.Specification;
039
040 public class FilterExampleSpecification<T> implements Specification<T> {
041
042 private Metamodel metamodel;
043 private Object filter;
044
045 private FilterExampleSpecification(Metamodel metamodel, Object filter) {
046 this.metamodel = metamodel;
047 this.filter = filter;
048 }
049
050 public static <T> FilterExampleSpecification<T> byExample(Metamodel metamodel, Object filter) {
051 return new FilterExampleSpecification<T>(metamodel, filter);
052 }
053
054 public Predicate toPredicate(Root<T> root, CriteriaQuery<?> query, CriteriaBuilder builder) {
055 List<Predicate> predicates = new ArrayList<Predicate>();
056
057 applyAttributes(predicates, root, builder, metamodel.entity(filter.getClass()), filter);
058
059 if (predicates.size() > 0)
060 return builder.and(predicates.toArray(new Predicate[predicates.size()]));
061
062 return null;
063 }
064
065 private void applyAttributes(List<Predicate> predicates, Path<?> root, CriteriaBuilder builder, ManagedType<?> filterType, Object filter) {
066 // Query by example : the filter is of the same type as the entity
067 PropertyDescriptor[] pds = null;
068 try {
069 // Query by bean filter
070 BeanInfo info = Introspector.getBeanInfo(filter.getClass());
071 pds = info.getPropertyDescriptors();
072 }
073 catch (Exception e) {
074 throw new RuntimeException("Could not introspect filter bean", e);
075 }
076
077 for (PropertyDescriptor pd : pds) {
078 Attribute<?, ?> attribute = filterType.getAttribute(pd.getName());
079 if (attribute == null)
080 continue;
081
082 if (attribute.getPersistentAttributeType() == Attribute.PersistentAttributeType.EMBEDDED) {
083 // Visit embedded elements recursively
084 try {
085 Object embedded = pd.getReadMethod().invoke(filter);
086 if (embedded != null) {
087 ManagedType<?> embeddedType = metamodel.embeddable(attribute.getJavaType());
088 applyAttributes(predicates, root.get(pd.getName()), builder, embeddedType, embedded);
089 }
090 }
091 catch (Exception e) {
092 throw new RuntimeException("Could not get filter property " + pd.getName(), e);
093 }
094
095 continue;
096 }
097
098 if (attribute.getPersistentAttributeType() != Attribute.PersistentAttributeType.BASIC)
099 continue;
100
101 Object value = null;
102 try {
103 value = pd.getReadMethod().invoke(filter);
104 }
105 catch (Exception e) {
106 throw new RuntimeException("Could not get filter property " + pd.getName(), e);
107 }
108
109 Predicate predicate = FilterSpecUtil.buildPredicate(root, builder, pd.getReadMethod().getReturnType(), pd.getName(), value);
110 if (predicate != null)
111 predicates.add(predicate);
112 }
113 }
114 }