关于python：如何从PySide访问QML \\ QtQuick控件？

How to access QML\QtQuick controls from PySide?

我正在尝试从启动QQmlApplication引擎的python文件访问FileDialog控件，以便检索文件路径属性。我已经在.qml文件中设置了信号，但是无法通过python文件中的id访问文件对话框来设置插槽。 application.py中的findChild方法返回None。这是代码：

application.py

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import sys
from PySide2.QtGui import QGuiApplication
from PySide2.QtQml import QQmlApplicationEngine, QQmlFileSelector

sys_argv = sys.argv
sys_argv += ['--style', 'material']
app = QGuiApplication(sys_argv)

window = QQmlApplicationEngine()
window.load("QML/main.qml")

fileDialog = window.findChild(QQmlFileSelector,"fileDialog")
print(fileDialog)

app.exec_()

Page1.qml

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import QtQuick 2.9
import QtQuick.Controls 2.2
import QtQuick.Dialogs 1.2

Page {
width: 600
height: 400

header: Label {
text: qsTr("Prepare Data")
horizontalAlignment: Text.AlignHCenter
font.pixelSize: Qt.application.font.pixelSize * 2
padding: 10
}

Button {
text: qsTr("Load data")
anchors.centerIn: parent
onClicked: fileDialog.visible = true
padding: 10
}

signal folderSelected()

FileDialog {
id: fileDialog
selectFolder: true
title: qsTr("Select the data directory")
folder: shortcuts.home
onAccepted: {
parent.folderSelected()
}
}
}

main.qml

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import QtQuick 2.0
import QtQuick.Controls 2.12
import QtQuick.Controls.Material 2.12

ApplicationWindow{
visible: true
title: qsTr("Main window")
width: 1000
height: 800

Material.theme: Material.Light
Material.accent: Material.Orange

SwipeView {
id: swipeView
anchors.fill: parent

Page1 {
}

Page2 {
}

Page3 {
}

}
}

在"将引用推送到QML"部分中的一个旧答案中，解释了如何从QML更新某些python对象，该方法是Qt建议的方法，并且是现在应使用的方法。使用当前方法，您需要建立一个在许多情况下可能有问题的对象名。

因此解决方案是创建一个导出到QML的QObject并更新qproperty，这将发出一个信号，该信号连接到我们可以执行所需逻辑的插槽。另一方面，FileDialog返回一个URL，因此该属性必须为QUrl：

main.qml

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import os
import sys
from PySide2 import QtCore, QtGui, QtQml

class FileManager(QtCore.QObject):
file_url_Changed = QtCore.Signal(QtCore.QUrl)

def __init__(self, parent=None):
super(FileManager, self).__init__(parent)
self._file_url = QtCore.QUrl()

def get_file_url(self):
return self._file_url

def set_file_url(self, file_url):
if self._file_url != file_url:
self._file_url = file_url
self.file_url_Changed.emit(self._file_url)

file_url = QtCore.Property(QtCore.QUrl, fget=get_file_url, fset=set_file_url, notify=file_url_Changed)

@QtCore.Slot(QtCore.QUrl)
def on_file_url_changed(file_url):
print(file_url.toLocalFile())

if __name__ == '__main__':
sys.argv += ['--style', 'material']
app = QtGui.QGuiApplication(sys.argv)

file_manager = FileManager()
file_manager.file_url_Changed.connect(on_file_url_changed)

engine = QtQml.QQmlApplicationEngine()
engine.rootContext().setContextProperty("file_manager", file_manager)
file = os.path.join(os.path.dirname(os.path.realpath(__file__)),"QML","main.qml")
engine.load(QtCore.QUrl.fromLocalFile(file))
if not engine.rootObjects():
sys.exit(-1)
sys.exit(app.exec_())

Page1.qml

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import QtQuick 2.9
import QtQuick.Controls 2.2
import QtQuick.Dialogs 1.2

Page {
width: 600
height: 400

header: Label {
text: qsTr("Prepare Data")
horizontalAlignment: Text.AlignHCenter
font.pixelSize: Qt.application.font.pixelSize * 2
padding: 10
}

Button {
text: qsTr("Load data")
anchors.centerIn: parent
onClicked: fileDialog.visible = true
padding: 10
}

FileDialog {
id: fileDialog
selectFolder: true
title: qsTr("Select the data directory")
folder: shortcuts.home
onAccepted: {
file_manager.file_url = fileDialog.fileUrl // <---
}
}
}