QTreeView的QAbstractItemModel：我做错了什么？(QAbstractItemModel for QTreeView: what an I doing wrong?)

 我想创建一个QAbstractItemModel的子类，以便在QTreeView使用它。 起初，我决定制作一个没有支持任何层次结构的简约模型。 它应该为2×3表提供简单的文本数据（只读一个）。 
 
 唉，它没有崩溃，但没有显示任何数据：只有几个列标题（1,2）。 不能有人告诉我，我做错了什么？ 
 
import os, sys

from PyQt5 import QtWidgets, QtCore, QtGui, QtSvg

from PyQt5.QtCore import QPointF, QRectF
from PyQt5.QtWidgets import QGraphicsItem


from gui.graphic_items import *



class MegaModel(QtCore.QAbstractItemModel):
    def __init__(self, parent=None):
        super().__init__(parent)

        self._root_item = 7.40
        pass

    def columnCount(self, parent_index):
        if parent_index.isValid():
            return 0
        else:
            return 2

    def rowCount(self, parent_index):
        if parent_index.isValid():
            return 0
        else:
            return 3

    def data(self, index, role):
        if index.isValid():
            return QtCore.QVariant("Oy vey!")
        else:
            return None

    def index(self, row, column, parent=QtCore.QModelIndex()):
        print("index", row, column, parent)

        if parent.isValid():
            print("valid")
            return parent.internalPointer()
        else:
            print("invalid")
            return self.createIndex(row, column, self._root_item)

    def parent(self, index):
        return QtCore.QModelIndex()


if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)


    mega_view = QtWidgets.QTreeView()

    mega_model = MegaModel()

    mega_view.setModel(mega_model)

    mega_view.show()

    sys.exit(app.exec_())

I want to create a subclass a QAbstractItemModel to use it in QTreeView. At first, I decided to make a minimalistic model without any hierarchy supported. It should give a 2-by-3 table with simple text data (read-only one).
 
Alas, It does not crash but does not show any data: only a few column headers (1, 2). Cannot someone tell me, what am I doing wrong?
 
import os, sys

from PyQt5 import QtWidgets, QtCore, QtGui, QtSvg

from PyQt5.QtCore import QPointF, QRectF
from PyQt5.QtWidgets import QGraphicsItem


from gui.graphic_items import *



class MegaModel(QtCore.QAbstractItemModel):
    def __init__(self, parent=None):
        super().__init__(parent)

        self._root_item = 7.40
        pass

    def columnCount(self, parent_index):
        if parent_index.isValid():
            return 0
        else:
            return 2

    def rowCount(self, parent_index):
        if parent_index.isValid():
            return 0
        else:
            return 3

    def data(self, index, role):
        if index.isValid():
            return QtCore.QVariant("Oy vey!")
        else:
            return None

    def index(self, row, column, parent=QtCore.QModelIndex()):
        print("index", row, column, parent)

        if parent.isValid():
            print("valid")
            return parent.internalPointer()
        else:
            print("invalid")
            return self.createIndex(row, column, self._root_item)

    def parent(self, index):
        return QtCore.QModelIndex()


if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)


    mega_view = QtWidgets.QTreeView()

    mega_model = MegaModel()

    mega_view.setModel(mega_model)

    mega_view.show()

    sys.exit(app.exec_())

原文：https://stackoverflow.com/questions/42553972