How to binding QAbstractTableModel and QML TableView ?

[David Ng]

Hi All ,

I would like create sample qt application that can extract data from python object to QML tableview .

So i search from google and than implement QAbstractTableModel my self .

Unfortunately , it don't work .

Please check source code first , bottom is my source code show what i doing .

Program most time report Segmentation fault : 11

In some time it can successful execute but empty result .

If i change setContextProperty timing from before load to after load QML . Program is fire . data , role names , rowCount ..etc. All thing has been invoked , just but no result to display .

If i don't using QML , just create QTableView is coding , everything is fire now .

But unfortunately again , i must use QML .

Any people can let me know what i wrong ??

My Source code here , DummyList is my implementation of QAbstractTableModel

import sys
import collections

from PyQt5 import Qt


class DummyList(Qt.QAbstractTableModel):
    __DEFAULT__ = Qt.QVariant()
    def __init__(self,*args,**kwargs):
        super(DummyList,self).__init__(*args,**kwargs)
        self.__roles = {}
        self.__data = []
        self.append_data(
            [
                ("hello_would", "HELOOWOULD",),
                ("foobar" , "ECHO",),
                ("zebra"  , "FOO",),
                ("ummmm"  , "BAR",)
            ],True
        )


    def append_data(self,value,header_update=False):

        last_index = self.rowCount()
        self.beginInsertRows(Qt.QModelIndex(),last_index,last_index)
        value = collections.OrderedDict(value)
        self.__data.append(value)
        self.endInsertRows()
        if header_update:
            for key in value.keys():
                if key not in self.__roles.values():
                    self.__roles[ Qt.Qt.UserRole + len(self.__roles) ] = key


    def headerData(self,section,orientation,role):

        if role == Qt.Qt.DisplayRole:
            column = self.__roles.get(Qt.Qt.UserRole + section,Qt.QVariant())
        else:
            column = self.__roles.get(role,Qt.QVariant())
        return column


    def columnCount(self,parent=Qt.QModelIndex()):

        return len(self.__data[0])


    def rowCount(self,parent=Qt.QModelIndex()):

        return len(self.__data)


    def roleNames(self):
        """
            Model only invoked while binding to QML view .
        """
        default_roles = super(DummyList,self).roleNames()
        default_roles.update({ key:Qt.QByteArray(value.encode()) for key,value in self.__roles.items()})
        return default_roles


    def data(self,index,role):

        row = index.row()
        if index.isValid():
            if role >= Qt.Qt.UserRole:
                """
                Only fire on binding to QML
                """
                column = self.__roles[role]
            elif role == Qt.Qt.DisplayRole:
                column = self.__roles[Qt.Qt.UserRole + index.column()]
            else:
                return DummyList.__DEFAULT__
            col_data = self.__data[row][column]
            return Qt.QVariant(col_data)
        else:
            return DummyList.__DEFAULT__


class MyWindow(Qt.QWidget):
    def __init__(self, *args):
        Qt.QWidget.__init__(self, *args)

        tablemodel = DummyList(self)
        tableview = Qt.QTableView()
        tableview.setModel(tablemodel)

        layout = Qt.QVBoxLayout(self)
        layout.addWidget(tableview)
        self.setLayout(layout)


def main(*args,**kwargs):
    # We instantiate a QApplication passing the arguments of the script to it:
    main_app = Qt.QApplication(list(args))

    """
        Load tableview in QML , it will Segmentation fault: 11
        or display empty table
    """

    qml_app_engine = Qt.QQmlApplicationEngine(
        main_app
    )
    qml_app_engine.rootContext().setContextProperty("tableModel",DummyList())#If set property here , raise segementation most time
    qml_app_engine.load(Qt.QUrl(sys.path[0]+"/hello_table.qml"))
    #qml_app_engine.rootContext().setContextProperty("tableModel",DummyList())#Nothing to show , but data method has been invoked
    new_root = qml_app_engine.rootObjects()[0]

    new_root.show()


    """
    Load with custom create widget , everything is fine
    """
    #w = MyWindow()
    #w.show()

    # Now we can start it.
    return_code = main_app.exec_()
    #del app.global_["qml_viewer"]
    return return_code

if __name__ == "__main__":
    sys.exit(main(*sys.argv))

QML Source code :

import QtQuick 2.4
import QtQuick.Controls 1.3
import QtQuick.Window 2.2
import QtQuick.Dialogs 1.2


ApplicationWindow {
    //property var tableModel
    title: qsTr("Hello World")
    width: 640
    height: 480
    TableView {
        model: tableModel
        anchors.fill: parent
        Component.onCompleted: console.log(tableModel)
        TableViewColumn {
            width:200
            role: "hello_would"
            title: "Hello Would"
        }
        TableViewColumn {
            width:200
            role: "foobar"
            title: "Foobar"
        }
        TableViewColumn {
            width:200
            role: "zebra"
            title: "Zebra"
        }
        TableViewColumn {
            width:200
            role: "ummmm"
            title: "Ummmm"
        }

    }


}