Using a File to Update the Log Viewer Window Using PyQt4

Question

I implemented a very simple log viewer in Python using PyQt4.

I am interested in using it to run a program, so the list view should be updated when a new line is added to the log file.

Here is my implementation (without hours):

import sys
from PyQt4.QtCore import *
from PyQt4.QtGui import *

class LogEntryModel(QAbstractListModel):
    def __init__(self, logfile, parent=None):
        super(LogEntryModel, self).__init__(parent)
        self.slurp(logfile)

    def rowCount(self, parent=QModelIndex()):
        return len(self.entries)

    def data(self, index, role):
        if index.isValid() and role == Qt.DisplayRole:
            return QVariant(self.entries[index.row()])
        else:
            return QVariant()        

    def slurp(self, logfile):
        self.entries = []        
        with open(logfile, 'rb') as fp:
            for line in fp.readlines():
                tokens = line.strip().split(' : ')
                sender = tokens[2]
                message = tokens[4]
                entry = "%s %s" % (sender, message)
                self.entries.append(entry)

class LogViewerForm(QDialog):
    def __init__(self, logfile, parent=None):
        super(LogViewerForm, self).__init__(parent)

        # build the list widget
        list_label = QLabel(QString("<strong>MoMo</strong> Log Viewer"))
        list_model = LogEntryModel(logfile)        
        self.list_view = QListView()
        self.list_view.setModel(list_model)
        list_label.setBuddy(self.list_view)

        # define the layout
        layout = QVBoxLayout()
        layout.addWidget(list_label)
        layout.addWidget(self.list_view)
        self.setLayout(layout)

if __name__ == "__main__":
    app = QApplication(sys.argv)
    form = LogViewerForm(sys.argv[1])
    form.show()
    app.exec_()

As shown, the application works as expected: open the file, analyze the contents (split into ' : 'and create a list) and display the list with QListView.

There is a class QFileSystemWatcherthat emits a signal fileChanged, but I don’t know where it is connect, and how to cause the row to be added to the data and update the view event.

Any help?

Thank.

Answer 1

python pyqt, "" :

import sys
from PyQt4.QtCore import *
from PyQt4.QtGui import *

class LogEntryModel(QAbstractListModel):
    def __init__(self, logfile, parent=None):
        super(LogEntryModel, self).__init__(parent)
        self.slurp(logfile)
        self.logfile = logfile

    def rowCount(self, parent=QModelIndex()):
        return len(self.entries)

    def data(self, index, role):
        if index.isValid() and role == Qt.DisplayRole:
            return QVariant(self.entries[index.row()])
        else:
            return QVariant()

    def slurp(self, logfile):
        self.entries = []
        with open(logfile, 'rb') as fp:
            for line in fp.readlines():
                tokens = line.strip().split(' : ')
                sender = tokens[2]
                message = tokens[4]
                entry = "%s %s" % (sender, message)
                self.entries.append(entry)

class LogViewerForm(QDialog):
    def __init__(self, logfile, parent=None):
        super(LogViewerForm, self).__init__(parent)

        self.watcher = QFileSystemWatcher([logfile], parent=None)
        self.connect(self.watcher, SIGNAL('fileChanged(const QString&)'), self.update_log)

        # build the list widget
        list_label = QLabel(QString("<strong>MoMo</strong> Log Viewer"))
        list_model = LogEntryModel(logfile)
        self.list_model = list_model
        self.list_view = QListView()
        self.list_view.setModel(self.list_model)
        list_label.setBuddy(self.list_view)

        # define the layout
        layout = QVBoxLayout()
        layout.addWidget(list_label)
        layout.addWidget(self.list_view)
        self.setLayout(layout)

    def update_log(self):
        print 'file changed'
        self.list_model.slurp(self.list_model.logfile)
        self.list_view.updateGeometries()


if __name__ == "__main__":
    app = QApplication(sys.argv)
    form = LogViewerForm(sys.argv[1])
    form.show()
    app.exec_()

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