[FIXED] Adding row to QTableView with model and and delegate widgets

Issue

I am trying to add a row to QTableView with a QAbstractTableModel and QItemDelegate where the widgets appear in the added row. From what I've read I need to call .edit(index) on each item of the added row to call createEditor where the widgets are created however I am getting edit: editing failed

QItemDelegate:

class Delegate(QItemDelegate):

    def __init__(self):
        QItemDelegate.__init__(self)

        self.type_items = ["1", "2", "3"]

    def createEditor(self, parent, option, index):

        # COMBOBOX, LINEEDIT, TIMEDIT
        if index.column() == 0:
            comboBox = QComboBox(parent)
            for text in self.type_items:
                comboBox.addItem(text, (index.row(), index.column()))
            return comboBox

        elif index.column() == 1:
            lineEdit = QLineEdit(parent)
            return lineEdit

        elif index.column() == 2:
            timeEdit = QTimeEdit(parent)
            return timeEdit

    def setEditorData(self, editor, index):
        value = index.model()._data[index.row()][index.column()]

        if index.column() == 0:
            editor.setCurrentIndex(self.type_items.index(value))

        elif index.column() == 1:
            editor.setText(str(value))

        elif index.column() == 2:
            editor.setTime(value)

QAbstractTableModel:

class TableModel(QAbstractTableModel):
    def __init__(self, data):
        super(TableModel, self).__init__()
        self._data = data

    def data(self, index, role):
        pass

    def rowCount(self, index=None):
        return len(self._data)

    def columnCount(self, index=None):
        return len(self._data[0])

Main:

class MainWindow(QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)

        localWidget = QWidget()

        self.table = QTableView(localWidget)

        data = [["1", "Hi", QTime(2, 1)], ["2", "Hello", QTime(3, 0)]]

        self.model = TableModel(data)
        self.table.setModel(self.model)
        self.table.setItemDelegate(Delegate())

        self.add_row = QPushButton("Add Row", localWidget)
        self.add_row.clicked.connect(self.addRow)

        for row in range(self.model.rowCount()):
            for column in range(self.model.columnCount()):
                index = self.model.index(row, column)
                self.table.openPersistentEditor(index)

        layout_v = QVBoxLayout()
        layout_v.addWidget(self.table)
        layout_v.addWidget(self.add_row)
        localWidget.setLayout(layout_v)
        self.setCentralWidget(localWidget)
        self.show()

    def addRow(self):

        new_row_data = ["3", "Howdy", QTime(9, 0)]

        self.model.beginInsertRows(QModelIndex(), self.model.rowCount(), self.model.rowCount())
        self.model._data.append(new_row_data)
        self.model.endInsertRows()
        for i in range(len(new_row_data)):
            index = self.table.model().index(self.model.rowCount()-1, i)
            self.table.edit(index)

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

How can I trigger the QItemDelegate's createEditor to create the widgets for the added row's items and setEditorData to populate them?

Solution

First of all, you could use openPersistentEditor as you already did in the __init__.

There are two reasons for the error in self.table.edit():

1. in order to allow editing of an item through edit(), the flags() function must be overridden and provide the Qt.ItemIsEditable flag;
2. you cannot call edit() multiple times on different indexes within the same function;

Then, there are other important problems in your code:

• you're not correctly using the model, as data() is not implemented;
• the delegates should use the base functions of the model whenever they provide standard behavior (accessing index.model()._data is not good);
• setEditorData is unnecessary, as long as the above aspects are respected: Qt automatically sets the data based on the data type and the editor class;
• setData() should be implemented in order to correctly set the data on the model, otherwise the new data won't be accessible;
• changes in the model structure (like creating a new row) should be done in the model class;

Here is a revised version of your code:

class Delegate(QItemDelegate):
    def __init__(self):
        QItemDelegate.__init__(self)
        self.type_items = ["1", "2", "3"]

    def createEditor(self, parent, option, index):
        if index.column() == 0:
            comboBox = QComboBox(parent)
            for text in self.type_items:
                comboBox.addItem(text, (index.row(), index.column()))
            return comboBox
        # no need to check for the other columns, as Qt automatically creates a
        # QLineEdit for string values and QTimeEdit for QTime values;
        return super().createEditor(parent, option, index)

    # no setEditorData() required


class TableModel(QAbstractTableModel):
    def __init__(self, data):
        super(TableModel, self).__init__()
        self._data = data

    def appendRowData(self, data):
        self.beginInsertRows(QModelIndex(), self.rowCount(), self.rowCount())
        self._data.append(data)
        self.endInsertRows()

    def data(self, index, role=Qt.DisplayRole):
        if role in (Qt.DisplayRole, Qt.EditRole):
            return self._data[index.row()][index.column()]

    def setData(self, index, value, role=Qt.EditRole):
        if role == Qt.EditRole:
            self._data[index.row()][index.column()] = value
            self.dataChanged.emit(index, index)
            return True
        return False

    def rowCount(self, index=None):
        return len(self._data)

    def columnCount(self, index=None):
        return len(self._data[0])

    def flags(self, index):
        # allow editing of the index
        return super().flags(index) | Qt.ItemIsEditable


class MainWindow(QMainWindow):
    # ...
    def addRow(self):
        row = self.model.rowCount()

        new_row_data = ["3", "Howdy", QTime(9, 0)]
        self.model.appendRowData(new_row_data)

        for i in range(self.model.columnCount()):
            index = self.model.index(row, i)
            self.table.openPersistentEditor(index)

Answered By - musicamante