listviewitem showing no data in QML application - c++

Question

I have a classes.
dataitem
datamodel
interface
networkconnector
In dataitem is specified item properties.
class MDataItem : public QObject
{
Q_OBJECT
Q_PROPERTY(QString host READ host WRITE setHost NOTIFY hostChanged)
Q_PROPERTY(QString service READ service WRITE setService NOTIFY serviceChanged)
Q_PROPERTY(QString status READ status WRITE setStatus NOTIFY statusChanged)
Q_PROPERTY(QString lastchck READ lastchck WRITE setLastChck NOTIFY lastchckChanged)
Q_PROPERTY(QString duration READ duration WRITE setDuration NOTIFY durationChanged)
Q_PROPERTY(QString info READ info WRITE setInfo NOTIFY infoChanged)
public:
explicit MDataItem(QObject *parent = 0);
QString host() const;
void setHost(const QString &newhost);
QString service() const;
void setService(const QString &newservice);
QString status() const;
void setStatus(const QString &newstatus);
QString lastchck() const;
void setLastChck(const QString &newlastchck);
QString duration() const;
void setDuration(const QString &newduration);
QString info() const;
void setInfo(const QString &newinfo);
signals:
void hostChanged();
void serviceChanged();
void statusChanged();
void lastchckChanged();
void durationChanged();
void infoChanged();
private:
QString m_host;
QString m_service;
QString m_status;
QString m_lastchck;
QString m_duration;
QString m_info;
};
In model is model specification
class MDataModel : public QAbstractTableModel
{
public:
enum Columns{
Host = Qt::UserRole,
Service = Qt::UserRole + 1,
Status = Qt::UserRole + 2,
Duration = Qt::UserRole + 3,
Info = Qt::UserRole + 4
};
MDataModel(QObject *parent = 0);
QHash<int, QByteArray> roleNames() const;
void fillData(QNetworkReply *r);
int rowCount(const QModelIndex &parent) const;
int columnCount(const QModelIndex &parent) const;
QVariant data(const QModelIndex &index, int role) const;
QVariant headerData(int section, Qt::Orientation orientation, int role) const;
private:
QString dataAt(int offset) const;
QList<MDataItem*> items_;
public:
void prepareDataFinished(QNetworkReply *r);
};
The network get some data from the web.
class MNetworkConnector : public QObject
{
Q_OBJECT
public:
MNetworkConnector(QObject *parent=0);
private:
QNetworkAccessManager *manager;
void getData();
private slots:
void replyFinished(QNetworkReply *r);
void requireAuth(QNetworkReply *r, QAuthenticator *a);
signals:
void dataWasChanged(QNetworkReply *r);
};
and in the interface the network fill data in the model:
class MInterface : public QObject
{
Q_OBJECT
public:
MInterface();
MDataModel *mainModel;
MNetworkConnector *newConnection;
MDataModel* getModel();
public slots:
void dataWasPrepared(QNetworkReply *r);
};
At this point everything is Ok. In the debuger I see that data are in the model, in the correct MDataItem format.
But when I add model to the QML listView - application show nothing.
Where is the problem? Can you push me on the right way?
Main.cpp looks this:
int main(int argc, char *argv[])
{
QGuiApplication app(argc, argv);
MInterface *myIface = new MInterface();
QQmlApplicationEngine engine;
engine.rootContext()->setContextProperty("MainModel", myIface->getModel());
engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
return app.exec();
}
Main qml file:
import QtQuick 2.5
import QtQuick.Window 2.2
import QtQml 2.0
Window {
visible: true
width: Screen.width / 2
height: Screen.height / 2
title: qsTr("webinfo")
ListView
{
id: myList
visible: true
header: Header{}
model: MainModel
delegate: Item
{
Rectangle
{
Text { text: host }
}
}
}
}
When I set debuger breakpoint into my modedata class and in the function which should return the data, debuger not stop there. It looks that program never go inside this function.
Maybe problem is how I set model? Function getmodel() return pointer only.
main.cpp:
engine.rootContext()->setContextProperty("MainModel", myIface->getModel());
minterface.cpp:
MDataModel* MInterface::getModel()
{
return this->mainModel;
}
There is MDataModel.cpp
MDataModel::MDataModel(QObject *parent) : QAbstractTableModel(parent)
{
}
int MDataModel::rowCount(const QModelIndex & /* parent */) const
{
return items_.count();
}
int MDataModel::columnCount(const QModelIndex & /* parent */) const
{
return 5;
}
QVariant MDataModel::data(const QModelIndex &index, int role) const
{
if (!index.isValid())
{
return QVariant();
}
if (role == Qt::DisplayRole)
{
switch(index.column()){
case Columns::Host:
return items_.value(index.row())->host();
case Columns::Service:
return items_.value(index.row())->service();
case Columns::Status:
return items_.value(index.row())->status();
case Columns::Duration:
return items_.value(index.row())->duration();
case Columns::Info:
return items_.value(index.row())->info();
}
}
return QVariant();
}
QVariant MDataModel::headerData(int section, Qt::Orientation orientation, int role) const
{
if (role != Qt::DisplayRole)
return QVariant();
if (orientation == Qt::Horizontal && role == Qt::DisplayRole)
{
switch(section){
case Columns::Host:
return tr("Host");
case Columns::Service:
return tr("Service");
case Columns::Status:
return tr("Status");
case Columns::Duration:
return tr("Duration");
case Columns::Info:
return tr("Info");
}
}
return QVariant();
}
void MDataModel::prepareDataFinished(QNetworkReply *r)
{
QList<MDataItem*> newItems;
MDataItem *item = new MDataItem();
QString data;
while(r->canReadLine())
{
data = r->readLine();
item = new MDataItem();
if(data.contains("warning", Qt::CaseInsensitive))
{
item->setStatus("WARNING");
}
else if(data.contains("critical", Qt::CaseInsensitive))
{
item->setStatus("CRITICAL");
}
else if(data.contains("unknown", Qt::CaseInsensitive))
{
item->setStatus("UNKNOWN");
}
item->setHost(reg.cap(0).replace("host=","").toUpper());
...
...
}
}
items_ = newItems;
qDebug() << items_;
}
QHash<int, QByteArray> MDataModel::roleNames() const
{
QHash<int, QByteArray> roles;
roles[Columns::Host] = "host";
roles[Columns::Service] = "service";
roles[Columns::Status] = "status";
roles[Columns::Duration] = "duration";
roles[Columns::Info] = "info";
return roles;
}

Answer 1

Your main problems are:
MDataModel inherits QAbstractTableModel instead of QAbstractListModel. This is not an absolute problem since you could use a QAbstractTableModel, but since you are using a ListView in QML you should prefer using QAbstractListModel.
You are mixing roles and columns. This is a consequence of the first point since QAbstractListModel hides the concept of column.
You do not signal the model (and therefore the view/QML) you changed the data. Whenever changes happen to the underlying data you must tell the model by calling functions by pair, depending on what the change is: beginResetModel()/endResetModel(), beginInsertRows()/endInsertRows(), beginRemoveRows()/endRemoveRows(), etc. There are also 2 unpaired signals for that purpose: dataChanged() and modelReset(). Note that you can get away by always calling modelReset(), but this is not a good practice and you should favor using the most sepcific pair of function.
You should also read Qt documentation:
Using C++ Models with Qt Quick Views > QAbstractItemModel subclass
QAbstractItemModel Class > Protected Functions
And here is you fixed model. I removed columnCount() and headerData() as you do not need them to make it work.
MDataModel.h
class MDataModel : public QAbstractListModel
{
public:
enum Role{
Host = Qt::UserRole,
Service,
Status,
Duration,
Info
};
MDataModel(QObject *parent = 0);
QHash<int, QByteArray> roleNames() const;
void fillData(QNetworkReply *r);
int rowCount(const QModelIndex &parent) const;
QVariant data(const QModelIndex &index, int role) const;
private:
QString dataAt(int offset) const;
QList<MDataItem*> items_;
public:
void prepareDataFinished(QNetworkReply *r);
};
MDataModel.cpp
MDataModel::MDataModel(QObject *parent) : QAbstractListModel(parent)
{
}
int MDataModel::rowCount(const QModelIndex & /* parent */) const
{
return items_.count();
}
QVariant MDataModel::data(const QModelIndex &index, int role) const
{
if (!index.isValid())
{
return QVariant();
}
switch(role){
// For C++ views
case Qt::DisplayRole:
return items_.value(index.row())->host();
// For QML views
case Host:
return items_.value(index.row())->host();
case Service:
return items_.value(index.row())->service();
case Status:
return items_.value(index.row())->status();
case Duration:
return items_.value(index.row())->duration();
case Info:
return items_.value(index.row())->info();
}
return QVariant();
}
void MDataModel::prepareDataFinished(QNetworkReply *r)
{
QList<MDataItem*> newItems;
MDataItem *item = new MDataItem();
QString data;
while(r->canReadLine())
{
data = r->readLine();
item = new MDataItem();
if(data.contains("warning", Qt::CaseInsensitive))
{
item->setStatus("WARNING");
}
else if(data.contains("critical", Qt::CaseInsensitive))
{
item->setStatus("CRITICAL");
}
else if(data.contains("unknown", Qt::CaseInsensitive))
{
item->setStatus("UNKNOWN");
}
item->setHost(reg.cap(0).replace("host=","").toUpper());
...
...
}
}
// Call beginResetModel() and endResetModel() to tell the model
// and the view the data changed.
beginResetModel();
items_ = newItems;
endResetModel();
qDebug() << items_;
}
QHash<int, QByteArray> MDataModel::roleNames() const
{
QHash<int, QByteArray> roles;
roles[Host] = "host";
roles[Service] = "service";
roles[Status] = "status";
roles[Duration] = "duration";
roles[Info] = "info";
// Add displayRole so that you can get what C++ views displays in QML
// e.g Text { text: host + ' ' + status + ' (' + displayRole +')' }
roles[Qt::DisplayRole] = "displayRole";
return roles;
}
QML fix
delegate: Component
{
Rectangle
{
width: 250
height: textItem.height
Text {
id: textItem
text: host + ' ' + status + ' (' + displayRole +')'
}
}
}

Answer 2

At this moment, my MDataModel.h and MDataModel.cpp looks like this:
MDataModel.h
class MDataModel : public QAbstractListModel
{
public:
enum icingaRoles{
host,
service,
status,
duration,
info
};
MDataModel(QObject *parent = 0);
QHash<int, QByteArray> roleNames() const;
void fillData(QNetworkReply *r);
int rowCount(const QModelIndex &parent) const;
QVariant data(const QModelIndex &index, int role) const;
private:
QString dataAt(int offset) const;
QList<MDataItem*> items_;
public:
void prepareDataFinished(QNetworkReply *r);
};
MDataModel.cpp
MDataModel::MDataModel(QObject *parent) : QAbstractListModel(parent)
{
}
int MDataModel::rowCount(const QModelIndex & /* parent */) const
{
return items_.count();
}
QVariant MDataModel::data(const QModelIndex &index, int role) const
{
if (!index.isValid())
{
return QVariant();
}
if (role == Qt::DisplayRole)
{
switch(index.column()){
case host:
return items_.value(index.row())->host();
case service:
return items_.value(index.row())->service();
case status:
return items_.value(index.row())->status();
case duration:
return items_.value(index.row())->duration();
case info:
return items_.value(index.row())->info();
}
}
return QVariant();
}
void MDataModel::prepareDataFinished(QNetworkReply *r)
{
QList<MDataItem*> newItems;
MDataItem *item = new MDataItem();
QString data;
while(r->canReadLine())
{
data = r->readLine();
QRegExp reg;
if(data.contains("statusbgwarning'><a href", Qt::CaseInsensitive) || data.contains("statusbgcritical'><a href", Qt::CaseInsensitive) || data.contains("statusbgunknown'><a href", Qt::CaseInsensitive))
{
item = new MDataItem();
newItems.append(item);
if(data.contains("warning", Qt::CaseInsensitive))
{
item->setStatus("WARNING");
}
else if(data.contains("critical", Qt::CaseInsensitive))
{
item->setStatus("CRITICAL");
}
else if(data.contains("unknown", Qt::CaseInsensitive))
{
item->setStatus("UNKNOWN");
}
...
...
}
// Call beginResetModel() and endResetModel() to tell the model
// and the view the data changed.
beginResetModel();
items_ = newItems;
endResetModel();
}
QHash<int, QByteArray> MDataModel::roleNames() const
{
QHash<int, QByteArray> roles;
roles[host] = "host";
roles[service] = "service";
roles[status] = "status";
roles[duration] = "duration";
roles[info] = "info";
return roles;
}