QFileSystemModel() / QTreeView()：在视图扩展之前遍历模型文件系统树

Question

我想为使用 PyQt5 创建的应用程序创建一个小部件。我希望用户能够 select 指定目录下文件系统层次结构中文件的任何子集。我已经扩展了 QFileSystemModel 以允许大致按照此

检查模型中的元素

example.

我希望用户能够在检查目录时修改目录内容的检查状态——甚至在子目录展开之前。

这样：

...树视图中折叠节点的 'under the hood'：

我面临的问题是，QTreeView - 似乎是 QFileSystemModel - 各自或一起通过仅报告已经查看过的模型项目来优化性能。直到我手动展开View中的子目录，才无法遍历Model中的数据。

为了说明，我添加了一个打印回调，并将其传递给我的（递归）tree-traversal 例程 - 以打印任何索引有多少 children。（见附件代码。）在我通过 double-clicking 扩展树视图中的子目录之前，它报告没有 children： Image 1 当我报告以下内容时点击 'one':

tree clicked: /Users/caleb/dev/ML/cloudburst-ml/data/test_dir/one
traverseDirectory():
model printIndex(): /Users/caleb/dev/ML/cloudburst-ml/data/test_dir/one
|children|: 0

...但是如果我展开视图 - 如 Image 2，那么我会看到所有 children，如下所示：

tree clicked: /Users/caleb/dev/ML/cloudburst-ml/data/test_dir/one
traverseDirectory():
model printIndex(): /Users/caleb/dev/ML/cloudburst-ml/data/test_dir/one
|children|: 7
child[0]: recursing
traverseDirectory():
model printIndex(): /Users/caleb/dev/ML/cloudburst-ml/data/test_dir/one/one_f
|children|: 0
child[1]: recursing
traverseDirectory():
model printIndex(): /Users/caleb/dev/ML/cloudburst-ml/data/test_dir/one/one_e
|children|: 0
child[2]: recursing
traverseDirectory():
model printIndex(): /Users/caleb/dev/ML/cloudburst-ml/data/test_dir/one/one_d
|children|: 0
child[3]: recursing
traverseDirectory():
model printIndex(): /Users/caleb/dev/ML/cloudburst-ml/data/test_dir/one/one_c
|children|: 0
child[4]: recursing
traverseDirectory():
model printIndex(): /Users/caleb/dev/ML/cloudburst-ml/data/test_dir/one/one_b
|children|: 0
child[5]: recursing
traverseDirectory():
model printIndex(): /Users/caleb/dev/ML/cloudburst-ml/data/test_dir/one/one_a
|children|: 6
child[0]: recursing
traverseDirectory():
model printIndex(): /Users/caleb/dev/ML/cloudburst-ml/data/test_dir/one/one_a/tfd
|children|: 0
child[1]: recursing
traverseDirectory():
model printIndex(): /Users/caleb/dev/ML/cloudburst-ml/data/test_dir/one/one_a/sgl
|children|: 0
child[2]: recursing
traverseDirectory():
model printIndex(): /Users/caleb/dev/ML/cloudburst-ml/data/test_dir/one/one_a/kjh
|children|: 0
child[3]: recursing
traverseDirectory():
model printIndex(): /Users/caleb/dev/ML/cloudburst-ml/data/test_dir/one/one_a/jyk
|children|: 0
child[4]: recursing
traverseDirectory():
model printIndex(): /Users/caleb/dev/ML/cloudburst-ml/data/test_dir/one/one_a/dgj
|children|: 0
child[5]: recursing
traverseDirectory():
model printIndex(): /Users/caleb/dev/ML/cloudburst-ml/data/test_dir/one/one_a/..
|children|: 0
child[6]: recursing
traverseDirectory():
model printIndex(): /Users/caleb/dev/ML/cloudburst-ml/data/test_dir/one/..
|children|: 0

我如何诱导子目录的加载，或模型对实际文件系统的反映的扩展？如何在用户单击视图小部件之前遍历 QFileSystemModel 的根路径？

这是我的代码：

import sys
from PyQt5 import QtWidgets, QtCore, QtGui


class FileTreeSelectorModel(QtWidgets.QFileSystemModel):
    def __init__(self, parent=None, rootpath='/'):
        QtWidgets.QFileSystemModel.__init__(self, None)
        self.root_path      = rootpath
        self.checks         = {}
        self.nodestack      = []
        self.parent_index   = self.setRootPath(self.root_path)
        self.root_index     = self.index(self.root_path)

        self.setFilter(QtCore.QDir.AllEntries | QtCore.QDir.Hidden | QtCore.QDir.NoDot)
        self.directoryLoaded.connect(self._loaded)

    def _loaded(self, path):
        print('_loaded', self.root_path, self.rowCount(self.parent_index))

    def data(self, index, role=QtCore.Qt.DisplayRole):
        if role != QtCore.Qt.CheckStateRole:
            return QtWidgets.QFileSystemModel.data(self, index, role)
        else:
            if index.column() == 0:
                return self.checkState(index)

    def flags(self, index):
        return QtWidgets.QFileSystemModel.flags(self, index) | QtCore.Qt.ItemIsUserCheckable

    def checkState(self, index):
        if index in self.checks:
            return self.checks[index]
        else:
            return QtCore.Qt.Checked

    def setData(self, index, value, role):
        if (role == QtCore.Qt.CheckStateRole and index.column() == 0):
            self.checks[index] = value
            print('setData(): {}'.format(value))
            return True
        return QtWidgets.QFileSystemModel.setData(self, index, value, role)

    def traverseDirectory(self, parentindex, callback=None):
        print('traverseDirectory():')
        callback(parentindex)
        if self.hasChildren(parentindex):
            print('|children|: {}'.format(self.rowCount(parentindex)))
            for childRow in range(self.rowCount(parentindex)):
                childIndex = parentindex.child(childRow, 0)
                print('child[{}]: recursing'.format(childRow))
                self.traverseDirectory(childIndex, callback=callback)
        else:
            print('no children')

    def printIndex(self, index):
        print('model printIndex(): {}'.format(self.filePath(index)))


class FileTreeSelectorDialog(QtWidgets.QWidget):
    def __init__(self):
        super().__init__()

        self.root_path      = '/Users/caleb/dev/ML/cloudburst-ml/data/test_dir/'

        # Widget
        self.title          = "Application Window"
        self.left           = 10
        self.top            = 10
        self.width          = 1080
        self.height         = 640

        self.setWindowTitle(self.title)         #TODO:  Whilch title?
        self.setGeometry(self.left, self.top, self.width, self.height)

        # Model
        self.model          = FileTreeSelectorModel(rootpath=self.root_path)
        # self.model          = QtWidgets.QFileSystemModel()

        # View
        self.view           = QtWidgets.QTreeView()

        self.view.setObjectName('treeView_fileTreeSelector')
        self.view.setWindowTitle("Dir View")    #TODO:  Which title?
        self.view.setAnimated(False)
        self.view.setIndentation(20)
        self.view.setSortingEnabled(True)
        self.view.setColumnWidth(0,150)
        self.view.resize(1080, 640)

        # Attach Model to View
        self.view.setModel(self.model)
        self.view.setRootIndex(self.model.parent_index)

        # Misc
        self.node_stack     = []

        # GUI
        windowlayout = QtWidgets.QVBoxLayout()
        windowlayout.addWidget(self.view)
        self.setLayout(windowlayout)

        QtCore.QMetaObject.connectSlotsByName(self)

        self.show()

    @QtCore.pyqtSlot(QtCore.QModelIndex)
    def on_treeView_fileTreeSelector_clicked(self, index):
        print('tree clicked: {}'.format(self.model.filePath(index)))
        self.model.traverseDirectory(index, callback=self.model.printIndex)


if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)
    ex = FileTreeSelectorDialog()
    sys.exit(app.exec_())

我在这里查看了几个链接

- 这并没有改变行为

[2] - 这提出了一个替代解决方案，但不适用于我的目的

[3] - 这处理了相同的类，但不是同一个问题

Answer 1

根据设计 QFileSystemModel 不会加载所有项目，因为该任务非常繁重，另一方面 hasChildren() 表示它是否有子目录或文件，但仅 rowCount() returns 由于设计问题可见的子项，已在 this report 中讨论。

所以你不应该使用 rowCount() 而是使用 QDirIterator:

来完成目录迭代的任务

def traverseDirectory(self, parentindex, callback=None):
    print('traverseDirectory():')
    callback(parentindex)
    if self.hasChildren(parentindex):
        path = self.filePath(parentindex)
        it = QtCore.QDirIterator(path, self.filter()  | QtCore.QDir.NoDotAndDotDot)
        while it.hasNext():
            childIndex =  self.index(it.next())
            self.traverseDirectory(childIndex, callback=callback)
    else:
        print('no children')

如果您的模型有很多关卡，我建议您在另一个线程中执行该任务，因为它会冻结 GUI。

QFileSystemModel() / QTreeView()：在视图扩展之前遍历模型文件系统树

QFileSystemModel() / QTreeView(): traverse model filesystem tree prior to view expansion

python

pyqt

qtreeview

qfilesystemmodel

pyqt5