    001// Copyright 2011-2013 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.ioc.util.ExceptionUtils;
    023import org.apache.tapestry5.jpa.EntityManagerManager;
    024import org.slf4j.Logger;
    025
    026import javax.persistence.EntityManager;
    027import javax.persistence.metamodel.EntityType;
    028import javax.persistence.metamodel.SingularAttribute;
    029import javax.persistence.metamodel.Type;
    030
    031public class JpaValueEncoder<E> implements ValueEncoder<E>
    032{
    033    private final EntityType<E> entity;
    034    private final EntityManagerManager entityManagerManager;
    035    private final String persistenceUnitName;
    036    private final TypeCoercer typeCoercer;
    037    private final Logger logger;
    038    private final String idPropertyName;
    039    private final PropertyAdapter propertyAdapter;
    040
    041    public JpaValueEncoder(final EntityType<E> entity,
    042            final EntityManagerManager entityManagerManager, final String persistenceUnitName,
    043            final PropertyAccess propertyAccess, final TypeCoercer typeCoercer, final Logger logger)
    044    {
    045        super();
    046        this.entity = entity;
    047        this.entityManagerManager = entityManagerManager;
    048        this.persistenceUnitName = persistenceUnitName;
    049        this.typeCoercer = typeCoercer;
    050        this.logger = logger;
    051
    052        final Type<?> idType = this.entity.getIdType();
    053
    054        final SingularAttribute<? super E, ?> idAttribute = this.entity.getId(idType.getJavaType());
    055
    056        idPropertyName = idAttribute.getName();
    057
    058        propertyAdapter = propertyAccess.getAdapter(entity.getJavaType()).getPropertyAdapter(
    059                idPropertyName);
    060
    061    }
    062
    063    /**
    064     * {@inheritDoc}
    065     */
    066    @Override
    067    public String toClient(final E value)
    068    {
    069        if (value == null)
    070            return null;
    071
    072        final Object id = propertyAdapter.get(value);
    073
    074        if (id == null)
    075        {
    076            return null;
    077        }
    078
    079        return typeCoercer.coerce(id, String.class);
    080    }
    081
    082    /**
    083     * {@inheritDoc}
    084     */
    085    @Override
    086    public E toValue(final String clientValue)
    087    {
    088        if (InternalUtils.isBlank(clientValue))
    089            return null;
    090
    091        Object id = null;
    092        final Class<E> entityClass = entity.getJavaType();
    093
    094        try
    095        {
    096
    097            id = typeCoercer.coerce(clientValue, propertyAdapter.getType());
    098        }
    099        catch (final Exception ex)
    100        {
    101            throw new RuntimeException(String.format(
    102                    "Exception converting '%s' to instance of %s (id type for entity %s): %s",
    103                    clientValue, propertyAdapter.getType().getName(), entityClass.getName(),
    104                    ExceptionUtils.toMessage(ex)), ex);
    105        }
    106
    107        final EntityManager em = entityManagerManager.getEntityManager(persistenceUnitName);
    108
    109        final E result = em.find(entityClass, id);
    110
    111        if (result == null)
    112        {
    113            // We don't identify the entity type in the message because the logger is based on the
    114            // entity type.
    115            logger.error(String.format(
    116                    "Unable to convert client value '%s' into an entity instance.", clientValue));
    117        }
    118
    119        return result;
    120    }
    121}