FileStorage.cpp Example File

    /* Copyright (c) 2012, 2013  BlackBerry Limited.
     *
     * 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.
     */

    #include "FileStorage.hpp"

    #include "Person.hpp"

    using namespace bb::cascades;

    const QString FileStorage::m_personsFilePath = "./data/PersonList.dat";

    FileStorage::FileStorage()
    {
    }

    FileStorage::~FileStorage()
    {
    }

    // Clear the objects in our custom data file.
    bool FileStorage::clear()
    {
        QFile peopleFile(m_personsFilePath);
        return peopleFile.remove();
    }
    bool FileStorage::save(int lastID, GroupDataModel *model)
    {
        QFile personFile(m_personsFilePath);

        if (!personFile.open(QIODevice::WriteOnly))
            return false;

        QDataStream stream(&personFile); // Open a stream into the file.

        const bool saved = serializeDataModel(lastID, model, &stream); // Put the data model into the stream.

        personFile.close();

        return saved;
    }

    bool FileStorage::serializeDataModel(int lastID, GroupDataModel* model, QDataStream* stream)
    {
        // This is a simple serialization function.
        // For more info on dealing with complex types,
        // or incorporating file versions see "Serializing data type in Qt"
        // http://qt-project.org/doc/qt-4.8/datastreamformat.html
        bool addedData = false;

        *stream << lastID;
        if (stream->status() == QDataStream::Ok) {
            for (int i = 0; i < model->size(); i++) {
                Person *person = (Person *) model->children()[i];
                *stream << person->customerID() << person->firstName()
                        << person->lastName();
                if (stream->status() != QDataStream::Ok) {
                    return addedData = false;
                }
            }
            addedData = true;
        }

        return addedData;
    }
    int FileStorage::load(int& lastID, GroupDataModel *model)
    {
        // return the number of persons loaded.
        int loadedCount = 0;

        // open the custom file for writing.
        QFile file(m_personsFilePath);
        if (!file.open(QIODevice::ReadOnly)) {
            return loadedCount;
        }

        // Load from the stream into the dataModel.
        // The function deserializeIntoDataModel() will create the person instances
        // and add them to the given dataModel
        QDataStream stream(&file);
        loadedCount = deserializeIntoDataModel(&stream, model, lastID);
        file.close();

        return loadedCount;
    }

    int FileStorage::deserializeIntoDataModel(QDataStream *stream, GroupDataModel *model, int& lastID)
    {
        // Return number of persons deserialized.
        int loadedCount = 0;

        // Check in case the stream is empty.
        if (stream->atEnd())
            return loadedCount;

        // 1. Get the last customer id from the stream and set the member.
        if (!loadLastCustomerID(stream, lastID))
            return loadedCount;

        // 2. Get the person objects.
        while (!stream->atEnd()) {
            if (loadPerson(stream, model)) {
                loadedCount++;
            } else {
                break; // Stop reading after error.
            }
        }

        return loadedCount;
    }

    bool FileStorage::loadPerson(QDataStream* stream, GroupDataModel *model)
    {
        bool loaded = false;

        // Load the data into temporary variables.
        QString id, firstName, lastName;
        *stream >> id >> firstName >> lastName;

        // Check for errors in the read.
        if (stream->status() == QDataStream::Ok) {
            // Add a new person object to the data model.
            model->insert(new Person(id, firstName, lastName)); // Note the model will delete Person when the time comes.
            loaded = true;
        }

        return loaded;
    }
    bool FileStorage::loadLastCustomerID(QDataStream* stream, int& id)
    {
        bool loaded = false;
        int lastID;

        // Get the last customer id first.
        // ID's will be generated by incrementing this number
        *stream >> lastID;

        // Check for errors in the read.
        if (stream->status() == QDataStream::Ok) {
            loaded = true;
            id = lastID; // return the id
        }

        return loaded;
    }