QTableView model crash when calling endInsertRows()

Question

I have been trying to update a QTableViewModel when inserting a new object that represents a row. I did follow the advise of several question in SO, but I cannot get an example to work.

After debugging, I found that the call to self.endInsertRows() produces the crash.

This is a minimal example:

import sys
from PyQt5.QtWidgets import *
from PyQt5 import QtCore, QtGui, QtWidgets


class Wire:

    def __init__(self, name, x, y, gmr, r):
        self.name = name
        self.x = x
        self.y = y
        self.r = r
        self.gmr = gmr


class WiresCollection(QtCore.QAbstractTableModel):

    def __init__(self, parent=None):
        QtCore.QAbstractTableModel.__init__(self, parent)

        self.header = ['Name', 'R (Ohm/km)', 'GMR (m)']

        self.index_prop = {0: 'name', 1: 'r', 2: 'gmr'}

        self.wires = list()

    def add(self, wire: Wire):
        """
        Add wire
        :param wire:
        :return:
        """
        row = len(self.wires)
        self.beginInsertRows(QtCore.QModelIndex(), row, row)
        self.wires.append(wire)
        self.endInsertRows()

    def delete(self, index):
        """
        Delete wire
        :param index:
        :return:
        """
        row = len(self.wires)
        self.beginRemoveRows(QtCore.QModelIndex(), row, row)
        self.wires.pop(index)
        self.endRemoveRows()

    def rowCount(self, parent=QtCore.QModelIndex()):
        return len(self.wires)

    def columnCount(self, parent=QtCore.QModelIndex()):
        return len(self.header)

    def parent(self, index=None):
        return QtCore.QModelIndex()

    def data(self, index, role=QtCore.Qt.DisplayRole):
        if index.isValid():
            if role == QtCore.Qt.DisplayRole:
                val = getattr(self.wires[index.row()], self.index_prop(index.column()))
                return str(val)
        return None

    def headerData(self, p_int, orientation, role):
        if role == QtCore.Qt.DisplayRole:
            if orientation == QtCore.Qt.Horizontal:
                return self.header[p_int]

    def setData(self, index, value, role=QtCore.Qt.DisplayRole):
        """
        Set data by simple editor (whatever text)
        :param index:
        :param value:
        :param role:
        """
        wire = self.wires[index.row()]
        attr = self.index_prop[index.column()]
        setattr(wire, attr, value)


class TowerBuilderGUI(QtWidgets.QDialog):

    def __init__(self, parent=None):
        """
        Constructor
        Args:
            parent:
        """
        QtWidgets.QDialog.__init__(self, parent)
        self.setWindowTitle('Tower builder')

        # GUI objects
        self.setContextMenuPolicy(QtCore.Qt.NoContextMenu)
        self.layout = QVBoxLayout(self)
        self.wires_tableView = QTableView()
        self.add_wire_pushButton = QPushButton()
        self.add_wire_pushButton.setText('Add')
        self.delete_wire_pushButton = QPushButton()
        self.delete_wire_pushButton.setText('Delete')

        self.layout.addWidget(self.wires_tableView)
        self.layout.addWidget(self.add_wire_pushButton)
        self.layout.addWidget(self.delete_wire_pushButton)

        self.setLayout(self.layout)

        # Model
        self.wire_collection = WiresCollection(self)

        # set models
        self.wires_tableView.setModel(self.wire_collection)

        # button clicks
        self.add_wire_pushButton.clicked.connect(self.add_wire_to_collection)
        self.delete_wire_pushButton.clicked.connect(self.delete_wire_from_collection)

    def msg(self, text, title="Warning"):
        """
        Message box
        :param text: Text to display
        :param title: Name of the window
        """
        msg = QMessageBox()
        msg.setIcon(QMessageBox.Information)
        msg.setText(text)
        # msg.setInformativeText("This is additional information")
        msg.setWindowTitle(title)
        # msg.setDetailedText("The details are as follows:")
        msg.setStandardButtons(QMessageBox.Ok)
        retval = msg.exec_()

    def add_wire_to_collection(self):
        """
        Add new wire to collection
        :return:
        """
        name = 'Wire_' + str(len(self.wire_collection.wires) + 1)
        wire = Wire(name, x=0, y=0, gmr=0, r=0.01)
        self.wire_collection.add(wire)

    def delete_wire_from_collection(self):
        """
        Delete wire from the collection
        :return:
        """
        idx = self.ui.wires_tableView.currentIndex()
        sel_idx = idx.row()

        if sel_idx > -1:
            self.wire_collection.delete(sel_idx)
        else:
            self.msg('Select a wire in the wires collection')


if __name__ == "__main__":

    app = QtWidgets.QApplication(sys.argv)
    window = TowerBuilderGUI()
    window.show()
    sys.exit(app.exec_())

Answer 1

As indicated in the comments you have 2 errors:

• The first is when you press add because when you add a new item you have to refresh the view and that's why it's called data() method and it's where the error is shown in self.index_prop(index.column()), index_pro is a dictionary so you should use [] instead of ().

  val = getattr(self.wires[index.row()], self.index_prop[index.column()])
  

• Another error is generated by the line idx = self.ui.wires_tableView.currentIndex(), the ui does not exist and it is not necessary, sure it is a remnant of a previous code, to access wires_tableView as this is a member of the class not it is necessary to use an intermediary, you must access directly with self: idx = self.wires_tableView.currentIndex()

The above are typos and probably mark it so that the question is closed there is another error that is not, and that is the reason for my answer.

In the line self.beginRemoveRows(...) you must pass the row that you are going to remove but you are passing the row that does not exist:

row = len(self.wires)
self.beginRemoveRows(QtCore.QModelIndex(), row, row)  # <---- row does not exist in the table

The solution is simple, change it by index:

def delete(self, index):
    """
    Delete wire
    :param index:
    :return:
    """
    self.beginRemoveRows(QtCore.QModelIndex(), index, index)
    self.wires.pop(index)
    self.endRemoveRows()