Linking QML file to Python file to retrive infomation from user input?

404Developer

I have never worked with GUI for python before and now I needed to and was looking for a GUI lib that didn't look like something from windows ME. So I found this and gave it a go, So I have my .qml file where I made my layout, and my .py file where I call the front end and start the application. Thats as far as I was able to get, I cant get info from my combo-box, I cant get the directory path from my browse button. I would like to know how to get this info. Any insight on how I can do this would be great!

.py file:

import sys
import os

# Import Modules
from PySide6.QtGui import QGuiApplication
from PySide6.QtQml import QQmlApplicationEngine
from PySide2.QtCore import QStringListModel, QObject, Slot

# Instance Class
if __name__ == "__main__":
    app = QGuiApplication(sys.argv)
    engine = QQmlApplicationEngine()
    engine.load(os.path.join(os.path.dirname(__file__), "qml/main.qml"))

    comportComboModel = ['Roll Size 1','Roll Size 2','Roll Size  3','Roll Size  4','Roll Size  5']
    engine.rootContext().setContextProperty("comModel", comportComboModel)

    # Close application
    if not engine.rootObjects():
        sys.exit(-1)
    sys.exit(app.exec_())

.qml file:

import Qt.labs.platform 1.1
import QtQuick 2.15
import QtQuick.Window 2.15
import QtQuick.Controls 2.15
import QtQuick.Controls.Material 2.15

ApplicationWindow{
    id: window
    width: 800
    height: 500
    visible: true
    title: qsTr("Darwill Roll Tool")

    // Set Flags
    flags: Qt.WindowCloseButtonHint | Qt.WindowMinimizeButtonHint | Qt.CustomizeWindowHint | Qt.MSWindowsFixedSizeDialogHint | Qt.WindowTitleHint

    // Set material Style
    Material.theme: Material.Dark
    Material.accent: Material.LightBlue
    
    Image {
        id: image
        width: 179
        height: 47
        source: "../imgs/darwill-logo-header-sml_0.png"
        anchors.left: parent.left
        anchors.top: parent.top
        anchors.margins: 30
    }

    Button {
        text: "Browse"
        onClicked: folderDialog.open()
        anchors.right: parent.right
        anchors.top: parent.top
        anchors.rightMargin: 240
        anchors.topMargin: 30
    }

    Button {
        text: "Create PDFs"
        onClicked: folderDialog.open()
        anchors.right: parent.right
        anchors.bottom: parent.bottom
        anchors.margins: 30
    }

    TextField {
        id: pathField
        width: 300
        text: qsTr("")
        selectByMouse: true
        placeholderText: qsTr("Path to PDF files")
        readOnly: true
        anchors.right: parent.right
        anchors.top: parent.top
        anchors.rightMargin: 320
        anchors.topMargin: 36
    }

    Label {
        text: "<strong>Created</strong>: jkuzera@darwill.com"
        anchors.right: parent.right
        anchors.bottom: parent.bottom
        anchors.margins: 10
    }

    ComboBox {
        id: comBox
        width: 200
        model: comModel
        anchors.right: parent.right
        anchors.top: parent.top
        anchors.margins: 30
    }

    Dialog {
        FolderDialog {
            id: folderDialog
            currentFolder: viewer.folder
            folder: StandardPaths.standardLocations(StandardPaths.PicturesLocation)[0]
            onAccepted: {
                console.log("You chose: " + folderDialog.folder)
            }
        }
    }
}

eyllanesc

@404Developer Before pointing out what you need, I must point out that you have made a mistake that can cause silence bugs: Use PySide6 together with PySide2. Do not do it.

You must bear in mind that:

If you want to use FolderDialog then the eventloop must be QApplication as indicated in the docs.
If you want to send information from QML to python then you must implement a QObject where a slot receives the information.

*.py

import sys
import os

# Import Modules
from PySide6.QtWidgets import QApplication
from PySide6.QtQml import QQmlApplicationEngine
from PySide6.QtCore import QObject, Slot


class Backend(QObject):
    @Slot(str)
    def foo(self, text):
        print(text)


# Instance Class
if __name__ == "__main__":
    app = QApplication(sys.argv)
    engine = QQmlApplicationEngine()

    backend = Backend(app)
    comportComboModel = [
        "Roll Size 1",
        "Roll Size 2",
        "Roll Size  3",
        "Roll Size  4",
        "Roll Size  5",
    ]
    engine.rootContext().setContextProperty("comModel", comportComboModel)
    engine.rootContext().setContextProperty("backend", backend)

    engine.load(os.path.join(os.path.dirname(__file__), "qml/main.qml"))

    # Close application
    if not engine.rootObjects():
        sys.exit(-1)
    sys.exit(app.exec())

*.qml

import Qt.labs.platform 1.1
import QtQuick 2.15
import QtQuick.Controls 2.15
import QtQuick.Controls.Material 2.15
import QtQuick.Window 2.15

ApplicationWindow {
    id: window

    width: 800
    height: 500
    visible: true
    title: qsTr("Darwill Roll Tool")
    // Set Flags
    flags: Qt.WindowCloseButtonHint | Qt.WindowMinimizeButtonHint | Qt.CustomizeWindowHint | Qt.MSWindowsFixedSizeDialogHint | Qt.WindowTitleHint
    // Set material Style
    Material.theme: Material.Dark
    Material.accent: Material.LightBlue

    Image {
        id: image

        width: 179
        height: 47
        source: "../imgs/darwill-logo-header-sml_0.png"
        anchors.left: parent.left
        anchors.top: parent.top
        anchors.margins: 30
    }

    Button {
        text: "Browse"
        onClicked: folderDialog.open()
        anchors.right: parent.right
        anchors.top: parent.top
        anchors.rightMargin: 240
        anchors.topMargin: 30
    }

    Button {
        text: "Create PDFs"
        onClicked: folderDialog.open()
        anchors.right: parent.right
        anchors.bottom: parent.bottom
        anchors.margins: 30
    }

    TextField {
        id: pathField

        width: 300
        text: qsTr("")
        selectByMouse: true
        placeholderText: qsTr("Path to PDF files")
        readOnly: true
        anchors.right: parent.right
        anchors.top: parent.top
        anchors.rightMargin: 320
        anchors.topMargin: 36
    }

    Label {
        text: "<strong>Created</strong>: jkuzera@darwill.com"
        anchors.right: parent.right
        anchors.bottom: parent.bottom
        anchors.margins: 10
    }

    ComboBox {
        id: comBox

        width: 200
        model: comModel
        anchors.right: parent.right
        anchors.top: parent.top
        anchors.margins: 30
        onCurrentTextChanged: backend.foo(comBox.currentText)
    }

    FolderDialog {
        id: folderDialog

        folder: StandardPaths.standardLocations(StandardPaths.PicturesLocation)[0]
        onAccepted: {
            console.log("You chose: " + folderDialog.folder);
        }
    }

}

404Developer

OK, I dont really follow as to what you mean by silence bugs. I want a way for the user to browse for a folder and select it and have it return the path which that does. I dont know any other way to do it. Do you have a suggestion on how to fix the issue you point out and maybe what a silence bug is?

eyllanesc

@404Developer It seems that you have not understood my comment.

A silent bug is one that initially does not cause problems but as the application progresses something fails, and by its nature is difficult to track. Those bugs are the worst.
The code from my previous comment is the solution, have you tested it?

404Developer

Ahhh I see! That makes sense. Now another question I have while I have someone clearly knowledge here, is it effective to keep grabbing the combo-box as its changed or only as I need it? Because I really only need all the data from the browse button, the combo-box after the create PDFs button is clicked. Is there a way I can set it up so that when the create PDFs button is clicked the data from browse, as well as the combo-box is passed to my python code?

eyllanesc

@404Developer Recommendation: Don't just copy code but understand it.

The logic is similar:

class Backend(QObject):
    @Slot(str, QUrl)
    def foo(self, combo, folder):
        print(combo, folder.toLocalFile())

onAccepted: {
    backend.foo(comBox.currentText, folderDialog.folder);
}

Note: remove onCurrentTextChanged: backend.foo(comBox.currentText)

404Developer

@eyllanesc said in Linking QML file to Python file to retrive infomation from user input?:

@Slot(str, QUrl)

Can you run down what the @Slot is for please? That as well as QUrl errors for me.

eyllanesc

@404Developer Precisely Slot is a decorator that allows to expose function to QML. I recommend you review some manuals or examples like https://qmlbook.github.io/. Unfortunately I am not a tutor so I will not respond anymore since in my opinion the problem has already been solved. Goodbye.

Have you imported QUrl: from PySide6.QtCore import QObject, Slot, QUrl? Trivial and obvious things I don't usually point out as I assume the OP has minimal knowledge of the tool.

404Developer

This post is deleted!

eyllanesc

@404Developer Okay, it was a mistake on my part, change:

    Button {
        text: "Create PDFs"
        onClicked: backend.foo(comBox.currentText, folderDialog.folder);
        anchors.right: parent.right
        anchors.bottom: parent.bottom
        anchors.margins: 30
    }

404Developer

@eyllanesc Ahh gotcha, Thank you for taking the time to help me out man. Very much appreciated!