PyQT5: why does my file window open immediately?

Question

This will probably be an easy one, but I have just started learning python, so please bear with me. The following class is supposed to generate the form fields I want :

import PyQt5
from PyQt5 import QtWidgets, QtCore
from PyQt5.QtWidgets import QFormLayout, QLabel, QFileDialog, QPushButton


def create_file_window():
    print("file dialog wanted")
    fileName, _ = QtWidgets.QFileDialog.getOpenFileName(None, 'Select Image', '', 'Image Files (*.png *.jpg '
                                                                                  '*.jpeg *.bmp)')
    if fileName:
        print(fileName)


class CreateFormElements(QtWidgets.QWidget):
    def __init__(self, *args, **kwargs):
        super(CreateFormElements, self).__init__(*args, **kwargs)

    def create_form_row(self, label, fieldType, *args, **kwargs):
        layout = QFormLayout()
        layout.addRow(QLabel(label), fieldType)
        self.setLayout(layout)
        # this arguments will tell me if I want a button, and if the button should open a file window
        connectType = kwargs.get('connectType', None)
        _fieldType = kwargs.get('_fieldType', None)
        # if this is a button that should open up a file window, call the create_file_window() function to make a
        # file window. currently no button is visible and the file window is opening up directly.
        if connectType == 'file' and _fieldType == 'button':
            print(fieldType)
            fieldType.setText("Upload new image")
            print('generate file')
            fieldType.clicked.connect(create_file_window())

Problem is, the file window does not wait for the button to be visible, instead, it opens up as soon as I run my main window. The code for the main window is given below:

import sys

from PyQt5 import QtWidgets
from PyQt5.QtWidgets import QApplication, QLabel, QMainWindow, QWidget, QVBoxLayout, QLineEdit, QFormLayout, \
    QFileDialog, QPushButton
from lib.create_form_elements import CreateFormElements


# view
# Subclass QMainWindow to customise your application's main window
class MainWindow(QMainWindow):

    def __init__(self, *args, **kwargs):
        super(MainWindow, self).__init__(*args, **kwargs)
        self.myWindow()

    def myWindow(self):
        self.setWindowTitle("My Awesome App")
        sizeObject = QtWidgets.QDesktopWidget().screenGeometry(-1)
        print(" Screen size : " + str(sizeObject.height()) + "x" + str(sizeObject.width()))

        self.width = 600
        self.height = 480
        self.left = 0
        self.top = 0
        self.setGeometry(self.left, self.top, self.width, self.height)
        layout = QVBoxLayout()
        elm = CreateFormElements()
        elm.create_form_row("Object Name: ", QPushButton(), connectType='file', _fieldType='button')
        layout.addWidget(elm)
        widget = QWidget()
        widget.setLayout(layout)
        self.setCentralWidget(widget)


app = QApplication(sys.argv)

window = MainWindow()
window.show()

app.exec_()

What am I doing wrong? How can I make it wait for the button click before opening up the file window? Thanks in advance for the help.

Answer 1

 fieldType.clicked.connect(create_file_window()) 

This creates the file window immediately because create_file_window is called. You need to pass the function to clicked.connect(...) without calling it:

fieldType.clicked.connect(create_file_window)

It will then be called when the clicked event is triggered.