QTreeView/QAbstractItemModel delete导致异常

Question

我编写了一个从QAbstractModelItem派生的类。它在QTreeView上使用。遗憾的是，正式文档示例没有显示如何在模型上添加或删除项目。我以为这样做很容易，所以我用我的方式破解了它。问题是删除选定的对象会导致异常。示例：

用户单击QTreeView上的一行，并希望删除它的所有子行(如果有的话)。这是被执行的代码：

MyModel.cpp:

// This gets called with the QModelIndex of the currently selected row.
void MyModel::remove(const QModelIndex &index) {
    if (!index.isValid()) 
        return;
    MyItem * selectedItem = static_cast<MyItem*>(index.internalPointer());
    beginRemoveRows(index, index.row(), index.row());
    // Call the method on the selected row object that will delete itself and all its children:
    selectedItem->destroy();
    endRemoveRows();
}

MyItem.h:

// A pointer list with child items.
std::vector<MyItem*> children;

MyItem.cpp:

// Deletes all children of this object and itself.
void MyItem::destroy(bool isFirst) {
    if (children.size() > 0) {
        // Each child needs to run this function, to ensure that all nested objects are properly deleted:
        for each (auto child in children)
            child->destroy(false);
        // Now that the children have been deleted from heap memory  clear the child pointer list:
        children.clear();
    }
    // This boolean determines wether this object is the selected row/highest object in the row hierachy. Remove this object from the parent's pointer list:
    if(isFirst)
        parent->removeChild(this);
    // And lastly delete this instance:
    if(!isFirst) // This will cause a memory leak, but it is necessary
        delete this; // <- because this throws an exception if I run this on the first object.
}

// Removes a single child reference from this instance's pointer list.
void MyItem::removeChild(MyItem * child)
{
    auto it = std::find(children.begin(), children.end(), child);
    children.erase(it);
}

现在，如果我们不介意小内存泄漏的话，这就很好了。^^

但是，如果我试图对第一个/选定的row对象运行delete命令，那么就会出现两个例外之一：

1. 该行有子行:引发的异常：读取访问冲突。这是0xDDDDDDDD.
2. 该行没有子行:引发的异常：写入访问冲突。_Parent_proxy为0x64F30630.

我保持了代码的简短，但希望它包含我的错误。或者有人知道一个很好的QTreeView/QAbstractItemModel示例，它演示了如何添加/删除项？

向索拉问好

Answer 1

我认为MyModel::remove方法有一个错误。beginRemoveRows将父索引作为第一个参数，而不是索引本身。你必须用这句话代替这句话：

beginRemoveRows(index.parent(), index.row(), index.row());