JsonRecordSetWriter.java

/*
 * (C) Copyright 2006-2012 Nuxeo SA (http://nuxeo.com/) and others.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Contributors:
 *     Nuxeo
 */

package org.nuxeo.ecm.automation.jaxrs.io;

import java.io.IOException;
import java.io.OutputStream;
import java.io.Serializable;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import java.util.Map;

import javax.ws.rs.Produces;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.ext.MessageBodyWriter;
import javax.ws.rs.ext.Provider;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.codehaus.jackson.JsonEncoding;
import org.codehaus.jackson.JsonFactory;
import org.codehaus.jackson.JsonGenerator;
import org.nuxeo.ecm.automation.core.util.PaginableRecordSet;
import org.nuxeo.ecm.automation.core.util.RecordSet;

/**
 * Manage JSON Marshalling for {@link RecordSet} objects
 *
 * @author <a href="mailto:tdelprat@nuxeo.com">Tiry</a>
 * @since 5.7
 */
@Provider
@Produces({ "application/json+nxentity", "application/json" })
public class JsonRecordSetWriter implements MessageBodyWriter<RecordSet> {

    protected static Log log = LogFactory.getLog(JsonRecordSetWriter.class);

    @Context
    JsonFactory factory;

    @Override
    public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
        boolean canUse = RecordSet.class.isAssignableFrom(type);
        return canUse;
    }

    @Override
    public long getSize(RecordSet t, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
        return -1L;
    }

    @Override
    public void writeTo(RecordSet records, Class<?> type, Type genericType, Annotation[] annotations,
            MediaType mediaType, MultivaluedMap<String, Object> httpHeaders, OutputStream out) throws IOException,
            WebApplicationException {
        try {
            writeRecords(out, records);
        } catch (IOException e) {
            log.error("Failed to serialize recordset", e);
            throw new WebApplicationException(500);
        }

    }

    protected void writeRecords(OutputStream out, RecordSet records) throws IOException {

        JsonGenerator jg = factory.createJsonGenerator(out, JsonEncoding.UTF8);

        jg.writeStartObject();
        jg.writeStringField("entity-type", "recordSet");

        if (records instanceof PaginableRecordSet) {
            PaginableRecordSet pRecord = (PaginableRecordSet) records;
            jg.writeBooleanField("isPaginable", true);
            jg.writeNumberField("resultsCount", pRecord.getResultsCount());
            jg.writeNumberField("pageSize", pRecord.getPageSize());
            jg.writeNumberField("maxPageSize", pRecord.getMaxPageSize());
            jg.writeNumberField("currentPageSize", pRecord.getCurrentPageSize());
            jg.writeNumberField("currentPageIndex", pRecord.getCurrentPageIndex());
            jg.writeNumberField("numberOfPages", pRecord.getNumberOfPages());
            jg.writeBooleanField("isPreviousPageAvailable", pRecord.isPreviousPageAvailable());
            jg.writeBooleanField("isNextPageAvailable", pRecord.isNextPageAvailable());
            jg.writeBooleanField("isLastPageAvailable", pRecord.isLastPageAvailable());
            jg.writeBooleanField("isSortable", pRecord.isSortable());
            jg.writeBooleanField("hasError", pRecord.hasError());
            jg.writeStringField("errorMessage", pRecord.getErrorMessage());
        }

        jg.writeArrayFieldStart("entries");
        for (Map<String, Serializable> entry : records) {
            jg.writeObject(entry);
        }

        if (records instanceof PaginableRecordSet) {
            PaginableRecordSet pRecord = (PaginableRecordSet) records;
            if (pRecord.hasAggregateSupport() && pRecord.getAggregates() != null && !pRecord.getAggregates().isEmpty()) {
                jg.writeObjectField("aggregations", pRecord.getAggregates());
            }
        }

        jg.writeEndArray();
        jg.writeEndObject();
        jg.flush();
    }

}