对 PyQt5 QFileDialog 感到困惑

Question

我正在尝试使用 GUI 文件选择对话框编写一个简单的脚本，并将选定的文件名返回给主程序代码。我在网上查找了一些想法，但我对这一切如何运作感到困惑。我有以下代码：

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QInputDialog, QLineEdit, QFileDialog, QMessageBox
from PyQt5.QtGui import QIcon

class App(QWidget):

    def __init__(self):
        super().__init__()
        self.title = 'Bla'
        self.left = 10
        self.top = 10
        self.width = 640
        self.height = 480
        self.initUI()

    def initUI(self):
        self.setWindowTitle(self.title)
        self.setGeometry(self.left, self.top, self.width, self.height)

        self.openFileNameDialog()

        self.show()

    def openFileNameDialog(self):
        options = QFileDialog.Options()
        options |= QFileDialog.DontUseNativeDialog
        fileName, _ = QFileDialog.getOpenFileName(self,"QFileDialog.getOpenFileName()", "","All Files (*);;Python Files (*.py)", options=options)

        return(fileName)


if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = App()
    alert = QMessageBox()
    alert.setText(f'selected file {ex}')
    alert.exec_()    
    sys.exit(app.exec_())

我添加了一个消息框来查看文件选择是否正常，但如果我运行它，消息框会显示：

selected file <_main_.App object at 0x0000000002EA9288>

同时，当我将消息框放入 openFileNameDialog 时，一切正常：

~snip~

def openFileNameDialog(self):
        options = QFileDialog.Options()
        options |= QFileDialog.DontUseNativeDialog
        fileName, _ = QFileDialog.getOpenFileName(self,"QFileDialog.getOpenFileName()", "","All Files (*);;Python Files (*.py)", options=options)

        alert = QMessageBox()
        alert.setText(f'selected file {fileName}')
        alert.exec_()

~snip~

所以问题是如何正确地将文件名返回给主程序？提前感谢您的帮助！

Answer 1

• ex是什么？它是一个代表小部件的变量，它不是文件名。
• 什么返回 openFileNameDialog 保存在某个变量中？ 不，那么该信息就丢失了。如果您想获取在某些方法中创建的信息，那么另一种方法是将其保存为类的属性。

综合以上，解决办法是：

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QFileDialog, QMessageBox


class App(QWidget):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.fileName = ""
        self.initUI()

    def initUI(self):
        self.setWindowTitle("Bla")
        self.setGeometry(10, 10, 640, 480)
        self.openFileNameDialog()
        self.show()

    def openFileNameDialog(self):
        options = QFileDialog.Options()
        options |= QFileDialog.DontUseNativeDialog
        fileName, _ = QFileDialog.getOpenFileName(
            self,
            "QFileDialog.getOpenFileName()",
            "",
            "All Files (*);;Python Files (*.py)",
            options=options,
        )
        self.fileName = fileName


if __name__ == "__main__":
    app = QApplication(sys.argv)
    ex = App()
    alert = QMessageBox()
    alert.setText(f"selected file {ex.fileName}")
    alert.exec_()
    sys.exit(app.exec_())