[FIXED] How do I get the text of an QLineEdit into a method?

Issue

I'm still not able to understand how to properly connect Qt_pushButton or Qt_LineEdit to methods. I would be so glad to get a explanation which even I do truly understand...

I've put together a pretty basic UI with Qt Designer. It contains a lineEdit called "lineEditTest" which I can indeed change by typing

self.lineEditTest.setText("changed Text")

However, I'm totally stuck with getting the text which the user entered back into my program. I would like to automatically submit the entered text into my function which sets a var to this value and returns it into my UI class. QLineEdit's signal editingFinished sounds perfect for that I guess? But it won't pass the text which the user entered into my function.

QLineEdit does have a property called "text" right? So it seems logical to me that I just have to pass another arg - apart from self - to my function called text.

My code does look like this but it obviously won't work at all:

from PyQt5 import QtWidgets, uic
import sys


class Ui(QtWidgets.QMainWindow):
    def __init__(self):
        super(Ui, self).__init__()
        uic.loadUi('test.ui', self)

        self.lineEditTest.setText("test")
        self.lineEditTest.editingFinished.connect(self.changeText(text))
        self.show()

    def changeText(self):
        currentText = text
        print (currentText)
        return currentText

app = QtWidgets.QApplication(sys.argv)
window = Ui()
app.exec_()

This will just crash with:

NameError: name 'text' is not defined`

Solution

The problem seems to be that the OP doesn't understand the logic of the signals and slots (I recommend you check here). The signals are objects that emit information, and the slots are functions (generally callable) that are connected to the signals to receive that information. And the information transmitted by the signal depends on each case, for example if you check the docs of editingFinished signal:

void QLineEdit::editingFinished()
This signal is emitted when the Return or Enter key is pressed or the line edit loses focus. Note that if there is a validator() or inputMask() set on the line edit and enter/return is pressed, the editingFinished() signal will only be emitted if the input follows the inputMask() and the validator() returns QValidator::Acceptable.

That signal does not send any information so do not expect to receive any information except knowing that the edition has ended by the user. So how can I get the text? Well, through the text() method of QLineEdit:

class Ui(QtWidgets.QMainWindow):
    def __init__(self):
        super(Ui, self).__init__()
        uic.loadUi("test.ui", self)

        self.lineEditTest.setText("test")
        self.lineEditTest.editingFinished.connect(self.changeText)
        self.show()

    def changeText(self):
        text = self.lineEditTest.text()
        print(text)

And how to do if the signal sends information? Then the slot (the function) that this connected will have as arguments to that information, for example if you use the textChanged signal that is emitted every time the text of the QLineEdit is changed, it should be as follows:

class Ui(QtWidgets.QMainWindow):
    def __init__(self):
        super(Ui, self).__init__()
        uic.loadUi("test.ui", self)

        self.lineEditTest.setText("test")
        self.lineEditTest.textChanged.connect(self.changeText)
        self.show()

    def changeText(self, text):
        print(text)
        # or
        # text = self.lineEditTest.text()
        # print(text)

Answered By - eyllanesc