Implement board persistence for example application "faketrello"

examples/faketrello/appdelegate.cpp

@@ -11,11 +11,31 @@ AppDelegate::AppDelegate(QObject *parent) : QObject(parent)
 
 int AppDelegate::run()
 {
-    // Pretend to load from file, but now it just load dummy daa.
-    m_board.load();
+    // NPM: Find filesystem location for persistent storage
+    QString persistDir =
+#ifdef Q_OS_ANDROID /* for android, store data in a location that doesn't get erased each app update */
+            QStandardPaths::writableLocation(QStandardPaths::GenericDataLocation) + "/" //"/storage/emulated/0/"
+             + "faketrello.example.qtproject.org";
+#else
+            QStandardPaths::writableLocation(QStandardPaths::DataLocation);
+#endif /* Q_OS_ANDROID */
+
+    // NPM: Create application-specific directory for persistent storage if it doesn't exist
+    QDir path;
+    path.setPath(persistDir);
+    if (!path.exists()) {
+      path.mkpath(persistDir);
+    }
 
     QCoreApplication* app = QCoreApplication::instance();
 
+    // NPM: load board layout from persistence file,
+    // or load dummy data if no persistence file, or parse error.
+    QString persistFilePath = persistDir + "/persist.json";
+    m_board.load(persistFilePath);
+
+    m_engine.rootContext()->setContextProperty("PersistFilePath", persistFilePath);
+
     m_engine.rootContext()->setContextProperty("App", this);
 
     m_engine.rootContext()->setContextProperty("CardListStore", cardListStore);
@@ -71,3 +91,51 @@ void AppDelegate::sync()
     runner.patch(cardListStore, patches);
 }
 
+// NPM -- see https://github.com/benlau/qsyncable/issues/2
+QByteArray AppDelegate::stringifyModel()
+{
+    QVariantList lists;
+    int count = cardListStore->storage().size();
+    for (int i = 0 ; i < count ; i++) {
+        lists << cardListStore->get(i);
+    }
+
+    QVariantMap map;
+    map["lists"] = lists;
+    QJsonObject object = QJsonObject::fromVariantMap(map);
+
+    QJsonDocument doc;
+    doc.setObject(object);
+    QByteArray bytes = doc.toJson(QJsonDocument::Indented);
+
+    return bytes;
+}
+
+// NPM -- see https://github.com/benlau/qsyncable/issues/2
+void AppDelegate::persistModel(const QString& filePath) {
+    QFile file(filePath);
+    file.open(QIODevice::WriteOnly);
+    file.write(AppDelegate::stringifyModel());
+    file.close();
+}
+
+// NPM -- see https://github.com/benlau/qsyncable/issues/2
+QByteArray AppDelegate::stringifyBoard()
+{
+    QVariantMap map = m_board.toMap();
+    QJsonObject object = QJsonObject::fromVariantMap(map);
+
+    QJsonDocument doc;
+    doc.setObject(object);
+    QByteArray bytes = doc.toJson(QJsonDocument::Indented);
+
+    return bytes;
+}
+
+// NPM -- see https://github.com/benlau/qsyncable/issues/2
+void AppDelegate::persistBoard(const QString& filePath) {
+    QFile file(filePath);
+    file.open(QIODevice::WriteOnly);
+    file.write(AppDelegate::stringifyBoard());
+    file.close();
+}

examples/faketrello/appdelegate.h

@@ -18,6 +18,11 @@ class AppDelegate : public QObject
 
 public slots:
 
+    QByteArray stringifyModel(); //NPM
+    void persistModel(const QString& filePath); //NPM
+    QByteArray stringifyBoard(); //NPM
+    void persistBoard(const QString& filePath); //NPM
+
     void addList();
 
     void addCard(const QString& listUuid);

examples/faketrello/board.cpp

@@ -109,9 +109,10 @@ void Board::removeCard(const QString& listUuid, const QString& cardUuid)
     }
 }
 
-void Board::load()
-{
+// NPM: original version of load(), now invoked from load() if persistence file missing or malformed
+void Board::failsafeLoad() {
     List list1 = list();
+
     list1 << card()
           << card()
           << card();
@@ -122,6 +123,55 @@ void Board::load()
     d->lists << list1 << list2;
 }
 
+// NPM: load persisted JSON board, or call failsafeload() above if first run or malformed persistence file.
+// see https://github.com/benlau/qsyncable/issues/2
+void Board::load(const QString& persistFilePath)
+{
+    QFile file(persistFilePath);
+    if(!file.open(QIODevice::ReadOnly)) {
+        qWarning() << "NOTE: using default board because no persistence file found: "<< persistFilePath;
+        Board::failsafeLoad();
+    }
+    else {
+        QTextStream stream (&file);
+        QString text = stream.readAll();
+        file.close();
+
+        QJsonParseError error;
+        QJsonDocument doc = QJsonDocument::fromJson(text.toUtf8(), &error);
+
+        if (error.error != QJsonParseError::NoError) {
+            qWarning() << "JSON::parse() error: "<< error.errorString();
+            qWarning() << "NOTE: using default board because persistence file is malformed: "<< persistFilePath;
+            Board::failsafeLoad();
+        }
+        else {
+            QVariantMap     map        = doc.object().toVariantMap();
+            QList<QVariant> lists      = map.value("lists").toList();
+            int             listsCount = lists.size();
+            for (int listsIdx = 0 ; listsIdx < listsCount ; listsIdx++) {
+                QMap<QString,QVariant> listsMap  = lists[listsIdx].toMap();
+                QString                listName  = listsMap.value("title").toString();
+                QList<QVariant>        listCards = listsMap.value("cards").toList();
+                int                    listNum   = listName.mid(5).toInt(); //"List %1" --> "%1"
+                if (d->nextListId <= listNum)
+                    d->nextListId = listNum + 1;
+                List cardsList(listName);
+                int cardsCount = listCards.size();
+                for (int cardIdx = 0 ; cardIdx < cardsCount ; cardIdx++) {
+                    QString cardName = listCards[cardIdx].toMap().value("text").toString();
+                    int     cardNum  = cardName.mid(5).toInt(); //"Card %1" --> "%1"
+                    if (d->nextCardId <= cardNum)
+                        d->nextCardId = cardNum + 1;
+                    Card card(cardName);
+                    cardsList << card;
+                }
+                d->lists << cardsList;
+            }
+        }
+    }
+}
+
 QVariantMap Board::toMap() const
 {
     QVariantMap res;

examples/faketrello/board.h

@@ -30,8 +30,11 @@ class Board
 
     int indexOfList(const QString& listUuid);
 
-    // Load from file, but now it just load dummy data for demo
-    void load();
+    // NPM: Load persisted board from file.
+    void load(const QString &persistFilePath);
+
+    // NPM: Load initial board if persistence file missing or malformed.
+    void failsafeLoad();
 
     QVariantMap toMap() const;
 

examples/faketrello/main.qml

@@ -1,9 +1,10 @@
 import QtQuick 2.3
 import QtQuick.Window 2.2
 import QtQuick.Layouts 1.1
+import QtQuick.Controls 1.1
 import "./views"
 
-Window {
+ApplicationWindow {
     id: window
     width: 640
     height: 480
@@ -23,5 +24,16 @@ Window {
 
     }
 
+    // NPM: Persist the model to file on application close.
+    // see https://github.com/benlau/qsyncable/issues/2
+    // BUG: when running on Android, putting application in background and closing
+    // (via swipe or close window button) doesn't call this -- you just get
+    // '"org.qtproject.example.faketrello" died.' message before anything can be done.
+    // However,  closing android app with back button works and persists the board.
+    onClosing: {
+        //console.log("Model=" + App.stringifyModel());
+        console.log("Exiting application... Persisting model to file " + PersistFilePath);
+        App.persistModel(PersistFilePath);
+        close.accepted = true;
+    }
 }
-