Message printing to a console widget not working properly

[wjassim]

Hello,

When I attempt to publish a message to a console widget with style='output,' an error occurs:

File ~\site-packages\pyqtgraph\console\repl_widget.py:139 in write
    if style == 'output' and row == self._lastCommandRow + 1:

TypeError: unsupported operand type(s) for +: 'NoneType' and 'int'`

However, when we set style='command,' the code functions perfectly. Any suggestions?

Below is a minimal working example:

import sys
from PySide6 import QtWidgets
import pyqtgraph as pg
from pyqtgraph.dockarea import DockArea, Dock
from pyqtgraph.console import ConsoleWidget

class MainWindow(QtWidgets.QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle('PyQtGraph Console Dock Example')

        # Create the dock area
        self.dock_area = DockArea()
        self.setCentralWidget(self.dock_area)

        # Create and add console dock
        self.console_dock = Dock("Console", size=(1, 1))
        self.console_widget = ConsoleWidget()
        self.console_dock.addWidget(self.console_widget)
        self.dock_area.addDock(self.console_dock, 'bottom')

        # Print some messages to the console
        self.print_to_console("Message 1")
        

    def print_to_console(self, message):
        """Print a message to the console widget"""
        self.console_widget.repl.write(message + '\n', style='output')
        #self.console_widget.repl.write(message + '\n', style='command')

if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    main_window = MainWindow()
    main_window.show()
    sys.exit(app.exec())

Thank you...

[mohass98]

Hello @wjassim.
The problem you are experiencing is due to this If-Statement.

        if style == 'output' and row == self._lastCommandRow + 1:
            # adjust style for first line of output
            firstLine, endl, strn = strn.partition('\n')
            self._setTextStyle('output_first_line')
            self.output.insertPlainText(firstLine + endl)

Within the condition, an attempt is made to add a 1 to the variable self._lastCommandRow. However, the variable is set to None by default. For this reason, the exception is raised, as None and Int cannot be added together. Only if style == 'command' is passed to the function, the variable self._lastCommandRow will be overwritten with the value of row.
I have tried to add an additional If statement within the write-method in repl_widget.py.

        row = cursor.blockNumber()
        if style == 'command':
            self._lastCommandRow = row

        if self._lastCommandRow is None:
            self._lastCommandRow = 0

        if style == 'output' and row == self._lastCommandRow + 1:
            # adjust style for first line of output
            firstLine, endl, strn = strn.partition('\n')
            self._setTextStyle('output_first_line')
            self.output.insertPlainText(firstLine + endl)

Then it also worked for me with style = 'output'. Please try it out and give feedback on whether you were able to achieve the desired behaviour. I hope that I have been able to help you with this.

[wjassim]

Hi @mohass98,

Thank you for your reply.

I have updated these lines in repl_widget.py according to your great note, and the updated code works perfectly. It is now valid for both 'command' and 'output' styles.

I am not sure how to inform the developers of pyqtgraph about this issue so they can modify the code. I can close this issue as the problem has been solved.

Thanks a million!
Best regards.