CODEWITHSUNDEEP
pythonqtpython-2.7qt4pyqt4
sdaau
sdaau

Reputation: 38629

Getting the path to changed file with QFileSystemWatcher?

From the snippet in How do I watch a file for changes?:

...
@QtCore.pyqtSlot(str)
def file_changed(path):
    print('File Changed!!!')
...

I've assumed that the argument path of the handler would be, well, the path of the file that changed (http://doc.qt.io/qt-4.8/qfilesystemwatcher.html doesn't really say what should be expected says "fileChanged ... signal is emitted when the file at the specified path is modified, renamed or removed from disk."). But, then I run the following example (ubuntu 14.04, python 2.7.6, corresponding py-qt4):

import sys, os
from PyQt4 import QtGui, QtCore
from PyQt4.QtCore import SIGNAL
from PyQt4 import Qt

mydir = os.path.dirname( os.path.realpath(__file__) )
myfile = os.path.join( mydir, "file.dat" )
print("myfile", myfile)

with open(myfile,"a+") as f:
  f.write("line 1\n")

class MyWindow(QtGui.QWidget):
  def __init__(self):
    global myfile
    QtGui.QWidget.__init__(self)
    self.button = QtGui.QPushButton('Test', self)
    self.button.clicked.connect(self.handleButton)
    layout = QtGui.QVBoxLayout(self)
    layout.addWidget(self.button)
    self.fs_watcher = QtCore.QFileSystemWatcher( [myfile] )
    self.fs_watcher.connect(self.fs_watcher, QtCore.SIGNAL('fileChanged(const QString &)'), self.file_changed) # or just 'fileChanged(QString)'
  def handleButton(self):
    print ('Hello World')
  @QtCore.pyqtSlot(str) #
  def file_changed(path):
    print('File Changed!!!' + str(path)) #

if __name__ == '__main__':
  app = QtGui.QApplication(sys.argv)
  window = MyWindow()
  # try to trigger file change here:
  with open(myfile,"a+") as f:
    f.write("line 2\n")
  window.show()
  sys.exit(app.exec_())

... and it outputs:

...
File Changed!!!<__main__.MyWindow object at 0xb5432b24>
...

So, that argument seems not to receive the path of the changed file, but instead a reference to the encompassing class?!

So how do I get the path to the file that changed?

Upvotes: 1

Views: 592

Answers (1)

ekhumoro
ekhumoro

Reputation: 120618

The file_changed slot needs a self parameter if it is to be a method of MyWindow:

    @QtCore.pyqtSlot(str)
    def file_changed(self, path):
        print('File Changed!!!' + str(path))

Upvotes: 1

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