Python: OSError: [Errno 9] 尝试写入 csv 时出现错误的文件描述符

Question

I'm a beginner in programming and I tried all my best to solve this error by my own. In the Code below I try to write something to a.csv file with only writing the name of the file once (in Line 7), to make it a more sustainable code.

But with the code below I get an "Bad file descriptor occurs" error. I already figured out that the error occurs because probably the.csv file gets closed too early. I don't know why because I don't call close() anywhere. As a workaround I can change the variable data to "NewFile.csv" everywhere in the code.

I really would appreciate a helping hand here to improve my programming.

Thanks for your help!

import sys
import csv
from qtpy import QtWidgets
from UI.mainwindow import Ui_MainWindow

#Dateiname/-pfad an Variable vergeben
data = "NewFile.csv"

app = QtWidgets.QApplication(sys.argv)

class MainWindow(QtWidgets.QMainWindow):

    def __init__(self, parent = None, data=data):
        super().__init__(parent)

        self.ui = Ui_MainWindow()
        self.ui.setupUi(self)
        self.setWindowTitle("Studentenverwaltung")

        self.ui.NewButton.clicked.connect(self.onNewButtonClick)
        self.loadTable(data)
        self.ui.SaveButton.clicked.connect(self.onSaveButtonClick)

    def loadTable(self, filename):
        self.ui.tableWidget.setRowCount(0)

        with open(filename, "r", newline="") as file:
            filereader = csv.reader(file, delimiter=";", quotechar='"')

            for row in filereader:
                first = row[0]
                last = row[1]
                subject = row[2]
                print(first + " " + last)

                newRow = self.ui.tableWidget.rowCount()

                self.ui.tableWidget.insertRow(newRow)
                self.ui.tableWidget.setItem(newRow, 0, QtWidgets.QTableWidgetItem(first))
                self.ui.tableWidget.setItem(newRow, 1, QtWidgets.QTableWidgetItem(last))
                self.ui.tableWidget.setItem(newRow, 2, QtWidgets.QTableWidgetItem(subject))

    def onSaveButtonClick(self, data):
        with open(data, "w", encoding="utf-8") as file:
            filewriter = csv.writer(file, delimiter=";", quotechar='"')

            totalRows = self.ui.tableWidget.rowCount()
            totalColumns = self.ui.tableWidget.columnCount()

            for row in range(totalRows):
                rowdata = []
                for column in range(totalColumns):
                    item = self.ui.tableWidget.item(row, column)
                    if item is not None:
                        rowdata.append(item.text())
                    else:
                        rowdata.append('')
                filewriter.writerow(rowdata)
                print(rowdata)

    def onNewButtonClick(self):
        newRow = self.ui.tableWidget.rowCount()
        self.ui.tableWidget.insertRow(newRow)
        self.ui.tableWidget.setItem(newRow, 0, QtWidgets.QTableWidgetItem(""))
        self.ui.tableWidget.setItem(newRow, 1, QtWidgets.QTableWidgetItem(""))
        self.ui.tableWidget.setItem(newRow, 2, QtWidgets.QTableWidgetItem(""))

        # Cursor auf neue Zelle setzen
        editingCell = self.ui.tableWidget.item(newRow, 0)
        self.ui.tableWidget.editItem(editingCell)

window = MainWindow()
window.show()

sys.exit(app.exec_())

Error Message:

OSError: [Errno 9] Bad file descriptor

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/User/Desktop/Coding/Python/PyQt/main.py", line 57, in onSaveButtonClick
    print(rowdata)
OSError: [Errno 9] Bad file descriptor

Process finished with exit code 134 (interrupted by signal 6: SIGABRT)

Answer 1

Remove the data parameter from the parameter list of onSaveButtonClick .

    def onSaveButtonClick(self):

When the function is called by Qt, it doesn't pass the filename as an argument. You want to use the global variable for that, and declaring a parameter shadows that.