001/*
002 * (C) Copyright 2015 Nuxeo SA (http://nuxeo.com/) and others.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 *
016 * Contributors:
017 *     Nicolas Chapurlat <nchapurlat@nuxeo.com>
018 */
019
020package org.nuxeo.ecm.core.io.marshallers.json;
021
022import static org.nuxeo.ecm.core.io.registry.MarshallingConstants.ENTITY_FIELD_NAME;
023
024import java.io.IOException;
025
026import org.codehaus.jackson.JsonNode;
027import org.nuxeo.ecm.core.io.registry.MarshallingException;
028
029/**
030 * Base class to read Nuxeo entity Json and convert it in Objects. This class checks the json is an object, the json
031 * property "entity-type" is present and as expected and delegate the body reading to an abstract method.
032 *
033 * @param <EntityType> The managed Java type.
034 * @since 7.2
035 */
036public abstract class EntityJsonReader<EntityType> extends AbstractJsonReader<EntityType> {
037
038    /**
039     * The expected "entity-type" property in the json.
040     */
041    private final String entityType;
042
043    /**
044     * @param entityType The expected "entity-type" property in the json.
045     */
046    public EntityJsonReader(String entityType) {
047        super();
048        this.entityType = entityType;
049    }
050
051    @Override
052    public final EntityType read(JsonNode jn) throws IOException {
053        if (!jn.isObject()) {
054            throw new MarshallingException("Json does not contain an object as expected");
055        }
056        JsonNode entityNode = jn.get(ENTITY_FIELD_NAME);
057        if (entityNode == null || entityNode.isNull() || !entityNode.isTextual()) {
058            throw new MarshallingException("Json object does not contain an entity-type field as expected");
059        }
060        String entityValue = entityNode.getTextValue();
061        if (!entityType.equals(entityValue)) {
062            throw new MarshallingException("Json object entity-type is wrong. Expected is " + entityType + " but was "
063                    + entityValue);
064        }
065        return readEntity(jn);
066    }
067
068    /**
069     * Implement this method to read the entity.
070     *
071     * @param jn A {@link JsonNode} pointing at the root of the json input.
072     * @return The parsed entity.
073     * @since 7.2
074     */
075    protected abstract EntityType readEntity(JsonNode jn) throws IOException;
076
077}