extensions/bustache/ApplyTemplate.cpp

/**
 * @file ApplyTemplate.cpp
 * ApplyTemplate class implementation
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */
#include <string.h>
#include <iostream>
#include <fstream>
#include <memory>
#include <string>
#include <set>

#include <boost/iostreams/device/mapped_file.hpp>

#include <bustache/model.hpp>
#include <bustache/format.hpp>

#include "ApplyTemplate.h"
#include "core/ProcessContext.h"
#include "core/ProcessSession.h"


namespace org {
namespace apache {
namespace nifi {
namespace minifi {
namespace processors {

core::Property ApplyTemplate::Template("Template", "Path to the input mustache template file", "");
core::Relationship ApplyTemplate::Success("success", "success operational on the flow record");

void ApplyTemplate::initialize() {
    //! Set the supported properties
    std::set<core::Property> properties;
    properties.insert(Template);
    setSupportedProperties(properties);
    //! Set the supported relationships
    std::set<core::Relationship> relationships;
    relationships.insert(Success);
    setSupportedRelationships(relationships);
}

void ApplyTemplate::onTrigger(const std::shared_ptr<core::ProcessContext>& context, const std::shared_ptr<core::ProcessSession>& session) {
    auto flowFile = session->get();

    if (!flowFile) {
        return;
    }

    std::string templateFile;
    context->getProperty(Template.getName(), templateFile);
    WriteCallback cb(templateFile, flowFile);
    session->write(flowFile, &cb);
    session->transfer(flowFile, Success);
}

ApplyTemplate::WriteCallback::WriteCallback(const std::string& path, const std::shared_ptr<core::FlowFile>& flowFile) {
    logger_ = logging::LoggerFactory<ApplyTemplate::WriteCallback>::getLogger();
    templateFile_ = path;
    flowFile_ = flowFile;
}

int64_t ApplyTemplate::WriteCallback::process(const std::shared_ptr<io::BaseStream> stream) {
    logger_->log_info("ApplyTemplate reading template file from %s", templateFile_);
    boost::iostreams::mapped_file_source file(templateFile_);

    bustache::format format(file);
    bustache::object data;

    for (const auto &attr : flowFile_->getAttributes()) {
        data[attr.first] = attr.second;
    }

    // TODO(calebj) write ostream reciever for format() to prevent excessive copying
    std::string ostring = to_string(format(data));
    stream->writeData(reinterpret_cast<uint8_t*>(const_cast<char*>(ostring.c_str())),
                      ostring.length());

    return ostring.length();
}

} /* namespace processors */
} /* namespace minifi */
} /* namespace nifi */
} /* namespace apache */
} /* namespace org */