qt - pyqt:试图了解 QAbstractDataModel 和 QTreeView 的插入行

Question

我正在使用 PyQt 来管理使用 QAbstractItemModel 的树 View 。到目前为止，我已经成功地实现了它，以便我可以加载数据、展开和折叠它以及编辑值。

但是，我无法做的一件事是将我的头围绕在插入和删除行上。

我正在尝试做的简短版本:

当用户编辑特定单元格时，我需要实际删除对象层次结构中的底层项目并将其替换为不同的项目。我在我的模型的 setData 方法中实现了这个。由于我不完全明白我在做什么，我似乎已经设置了它以便它出现段错误。

基本上，我只需要更好地理解数据模型如何与 QModelIndex 交互，但阅读和重新阅读文档似乎并没有启发我。任何帮助(或任何指向体面教程的链接 - 最好，但不一定，在 python 中 - 也将不胜感激)。

这是我正在使用的代码示例:

#---------------------------------------------------------------------------
def setData(self, index, value, role=QtCore.Qt.EditRole):
    """
    Sets the data. 
    """
    if index.isValid() and (0 <= index.row() < self.rowCount()):

        item = index.internalPointer()
        value = value.toString()
        if index.column() == 5:
            # rip out the current object and replace it with a new one of 
            # the correct datatype.

            #next 4 lines get info from my underlying hierarchy of objects
            dataType = str(value)
            parent = item.get_parent()
            name = item.get_name()
            row = parent.get_row_of_child(name)

            #assuming everything is ok, I now am trying to manage the
            #underlying objects
            if row != None:

                #I am calling this because I think I need to, but don't
                #really know if it is called for here or not
                self.beginInsertRows(self.parent(index), row, 1)

                #Next 3 lines create and initialize a new underlying 
                #object that will be inserted.
                newItem = self.root.create_template_param_obj(dataType, 
                                                              name, 
                                                              parent)
                newItem.set_index(row)
                newItem.set_default_value(item.get_default_value())

                #now I remove the old object from my underlying
                #hierarchy and insert the new one
                parent.remove_child_at_row(row)
                parent.insert_child_at_row(newItem, row)

                #this is where I get lost. I *think* I need to point to 
                #the new underlying object (i.e. rebuild the index)
                #so I am going to call the data model's index method.
                #But that needs the index of the parent, so first I
                #call the data model's parent method to get the index
                #of the parent. But this code segfaults (I think it 
                #is the treeview that actually freaks out because this
                #setData method completes properly before the whole thing
                #crashes. Does anyone have a pointer to a decent tutorial
                #that will explain how data models and mode indexes work?
                self.index(row, 5, self.parent(index))
                self.endInsertRows()

        self.emit(QtCore.SIGNAL("dataChanged(QModelIndex,QModelIndex)"), 
                                 index, index)
        return True

    #Ignore any role other than the edit role
    return False

#---------------------------------------------------------------------------
def index(self, row, column, parent):
    """
    Connect the data model to the actual object hierarchy.
    """
    if not self.hasIndex(row, column, parent):
        return QtCore.QModelIndex()

    if not parent.isValid():
        parentItem = self.root
    else:
        parentItem = parent.internalPointer()

    childItem = parentItem.get_child_at_row(row)
    if childItem:
        return self.createIndex(row, column, childItem)
    else:
        return QtCore.QModelIndex()


#---------------------------------------------------------------------------
def parent(self, index):
    """
    Returns a QModelIndex of the parent
    """
    if not index.isValid():
        return QtCore.QModelIndex()

    childItem = index.internalPointer()
    if not childItem:
        return QtCore.QModelIndex()

    parentItem = childItem.get_parent()

    if parentItem == self.root:
        return QtCore.QModelIndex()

    return self.createIndex(parentItem.get_index(), 0, parentItem)

Answer 1

我会试着给你一些提示，我记得当我不得不为我的应用程序实现它时，这部分也让我很兴奋!

因此，据我所知，您必须实现以下虚拟方法:

virtual bool insertRows(int Row, int Count, const QModelIndex& rParent);
virtual bool removeRows(int Row, int Count, const QModelIndex& rParent = QModelIndex());

bool SuperModel::insertRows(int Row, int Count, const QModelIndex& rParent)
{
 ...
    // On débute l'insertion des lignes.
    beginInsertRows(rParent, Row, Row + Count -1);
    // ... Perform insertion here, you'll have something like
    pParent->addChild(Row);
    endInsertRows();
}

bool SuperModel::removeRows(int Row, int Count, const QModelIndex& rParent)
{
    ...
    beginRemoveRows(rParent, Row, Row + Count -1);
    // ... Perform removing here, you'll have something like
    pParent->removeChild(Row);
    endRemoveRows();
}

更多信息:http://doc.qt.io/archives/qt-4.7/qabstractitemmodel.html#insertRows

我希望它会对你有所帮助......它不在 PyQt 中，但希望它会给你一些提示......