如何使用QSortFilterProxyModel过滤只显示子节点及其父节点的树模型？
我有一个从 QAbstractItemModel 派生的工作树模型，我希望使用 QSortFilterProxyModel 子类对其进行过滤，以仅显示某些条件的子节点。例如，我有以下树：
A
- B
-- C1
-- C1
-- C1
--- C2
- D
- E
我想用节点名称 == C1 的条件来过滤此树，并仅显示具有 C1 的节点及其子节点，如下所示：
C1
C1
C1
- C2
我已经有一个重新实现了 filterAcceptsRow() 的子类可以部分完成我想要的操作，但它仍然会显示 C1 节点的父节点和祖父节点：
A
- B
-- C1
-- C1
-- C1
--- C2
我认为这是因为要考虑子节点，它们的父节点必须通过 filterAcceptsRow() 测试，对吗？如何实现 filterAcceptRows() 或其他方法，以便它可以执行我所描述的操作？
我曾在 qtcentre 和 qtforum 中问过这个问题，但没有得到任何有用的答复。我尝试直接使用 filterAcceptsRow() 内的 beginMoveRows 和 endMoveRows 移动 QSortFilterProxyModel 子类的索引，但这只会由于危险的 const_cast 而导致测试应用程序崩溃。
I have a working tree model derived from QAbstractItemModel and I wish to filter it using a QSortFilterProxyModel subclass to display only children nodes of certain criteria. For example I have the following tree:
A
- B
-- C1
-- C1
-- C1
--- C2
- D
- E
I want to filter this tree with the condition that the node has name == C1 and display only the nodes with C1 and their children like this:
C1
C1
C1
- C2
I already have a subclass with filterAcceptsRow() re-implemented that can partially do what I want but it will still show the parent and grandparent of C1 nodes:
A
- B
-- C1
-- C1
-- C1
--- C2
I think this is because for children nodes to even be considered, their parent has to pass the filterAcceptsRow() test, am I right? How can I implement filterAcceptRows() or other methods such that it can do what I have described?
I have asked this question sometime back in qtcentre and qtforum but did not get any useful reply. I tried to move the indices of the QSortFilterProxyModel subclass directly using beginMoveRows and endMoveRows inside filterAcceptsRow() but that just crashes the test application due to dangerous const_cast.
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好的，我找到了解决我的问题的方法。只需使用 QTreeView::setRootIndex() 并将索引 B 作为输入参数即可。索引 B 成为 QTreeView 的根索引，它是隐藏的，只有它的子项完整显示。
找到这个解决方案后我感到非常愚蠢。我猜我太专注于使用代理模型来修改数据的呈现方式，我完全忘记了 QTreeView。
Okay, I've found a solution to my problem. Just use QTreeView::setRootIndex() with index B as the input argument. Index B becomes the root index of the QTreeView, which is hidden and only its children are shown in full.
I felt really dumb after finding this solution. Guess I was too focused on using the proxy model to modify how the data is presented, I had totally forgotten about QTreeView.
我认为使用 QSortFilterProxyModel 不可能实现这一点。原因是此类仅过滤元素 - 因为它根据给定的条件隐藏（或不隐藏）某些元素。您想要做的是将树重组为新的树（从根子节点的任意位置选择元素）。这只能通过创建您自己的 QProxyModel 后代并实现自己的树重建以及在新旧树之间映射索引来实现。
准确描述如何做到这一点对于这里的答案来说有点长。
I dont think this is possible to achive using QSortFilterProxyModel. The reason for that is that this class only filters elements - menas it hides (or not) some elements, basing on given criteria. What you want to do is restructuring tree into new one (having choosen elements from arbitary position at root-children). This is only possible by creating your own QProxyModel descendant and implementing yourself tree-rebuilding, and mapping indexes between old and new tree.
Describing exactly how to do this is a bit long for an answer here.
当然 setRootIndex 是这种情况的解决方案，但如果您要寻找更复杂的模型操作，您可以考虑使用自定义代理模型，例如 http://lynxline.com/category/models/
Of course setRootIndex is the solution for this case, but if you will be looking for more complicated model manipulations you may consider using custom proxy models like http://lynxline.com/category/models/