001// Copyright 2011 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007// http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5.internal.jpa;
016
017import org.apache.tapestry5.ValueEncoder;
018import org.apache.tapestry5.ioc.internal.util.InternalUtils;
019import org.apache.tapestry5.ioc.services.PropertyAccess;
020import org.apache.tapestry5.ioc.services.PropertyAdapter;
021import org.apache.tapestry5.ioc.services.TypeCoercer;
022import org.apache.tapestry5.jpa.EntityManagerManager;
023import org.slf4j.Logger;
024
025import javax.persistence.EntityManager;
026import javax.persistence.metamodel.EntityType;
027import javax.persistence.metamodel.SingularAttribute;
028import javax.persistence.metamodel.Type;
029
030public class JpaValueEncoder<E> implements ValueEncoder<E>
031{
032    private final EntityType<E> entity;
033    private final EntityManagerManager entityManagerManager;
034    private final String persistenceUnitName;
035    private final TypeCoercer typeCoercer;
036    private final Logger logger;
037    private final String idPropertyName;
038    private final PropertyAdapter propertyAdapter;
039
040    public JpaValueEncoder(final EntityType<E> entity,
041            final EntityManagerManager entityManagerManager, final String persistenceUnitName,
042            final PropertyAccess propertyAccess, final TypeCoercer typeCoercer, final Logger logger)
043    {
044        super();
045        this.entity = entity;
046        this.entityManagerManager = entityManagerManager;
047        this.persistenceUnitName = persistenceUnitName;
048        this.typeCoercer = typeCoercer;
049        this.logger = logger;
050
051        final Type<?> idType = this.entity.getIdType();
052
053        final SingularAttribute<? super E, ?> idAttribute = this.entity.getId(idType.getJavaType());
054
055        idPropertyName = idAttribute.getName();
056
057        propertyAdapter = propertyAccess.getAdapter(entity.getJavaType()).getPropertyAdapter(
058                idPropertyName);
059
060    }
061
062    /**
063     * {@inheritDoc}
064     */
065    public String toClient(final E value)
066    {
067        if (value == null)
068            return null;
069
070        final Object id = propertyAdapter.get(value);
071
072        if (id == null)
073        {
074            return null;
075        }
076
077        return typeCoercer.coerce(id, String.class);
078    }
079
080    /**
081     * {@inheritDoc}
082     */
083    public E toValue(final String clientValue)
084    {
085        if (InternalUtils.isBlank(clientValue))
086            return null;
087
088        Object id = null;
089        final Class<E> entityClass = entity.getJavaType();
090
091        try
092        {
093
094            id = typeCoercer.coerce(clientValue, propertyAdapter.getType());
095        }
096        catch (final Exception ex)
097        {
098            throw new RuntimeException(String.format(
099                    "Exception converting '%s' to instance of %s (id type for entity %s): %s",
100                    clientValue, propertyAdapter.getType().getName(), entityClass.getName(),
101                    InternalUtils.toMessage(ex)), ex);
102        }
103
104        final EntityManager em = entityManagerManager.getEntityManager(persistenceUnitName);
105
106        final E result = em.find(entityClass, id);
107
108        if (result == null)
109        {
110            // We don't identify the entity type in the message because the logger is based on the
111            // entity type.
112            logger.error(String.format(
113                    "Unable to convert client value '%s' into an entity instance.", clientValue));
114        }
115
116        return result;
117    }
118}