The QLineEdit class is a single line text box control that can enter a single line string.

QLineEdit allows users to enter and edit single lines of plain text and provides many useful editing features, including: undo and redo, cut and paste, and drag and drop (see setDragEnabled()).

By changing the echoMode() of the input box, it can also be set to a “write only” field for entering passwords, etc.

The length of the text can be limited to maxLength(), which can be arbitrarily limited using a validator() or inputMask(). When toggling validator and input mask in the same input box, it is best to clear the validator or input mask to prevent uncertain behavior.

Book: Create Desktop Apps with Python PyQt5

QLineEdit example

The 1st text box: shows text using custom fonts, right alignment, and allowing integer entries.

The 2nd text box: restricts entry to two decimal places.

The 3rd text box: set the mask input format and the input mask should be used for the phone number.

The 4th text box: which needs to transmit the signal textChanged, is connected to the slot function textchanged().

The 5th text box: set the display mode to Password.

The 6th text box: showing a default text that cannot be edited, is set to read-only.

from PyQt5.QtWidgets import QApplication,QLineEdit,QWidget,QFormLayout
from PyQt5.QtGui import QIntValidator,QDoubleValidator,QFont
from PyQt5.QtCore import Qt
import sys

class lineEditDemo(QWidget):
        def __init__(self,parent=None):
                super().__init__(parent)
                e1 = QLineEdit()
                e1.setValidator(QIntValidator())
                e1.setMaxLength(4)
                e1.setAlignment(Qt.AlignRight)
                e1.setFont(QFont("Arial",20))

                e2 = QLineEdit()
                e2.setValidator(QDoubleValidator(0.99,99.99,2))
                e3 = QLineEdit()
                e3.setInputMask("+99_9999_999999")

                e4 = QLineEdit()
                e4.textChanged.connect(self.textchanged)

                e5 = QLineEdit()
                e5.setEchoMode(QLineEdit.Password)

                e6 = QLineEdit("Hello PyQt5")
                e6.setReadOnly(True)
                e5.editingFinished.connect(self.enterPress)

                flo = QFormLayout()
                flo.addRow("integer validator",e1)
                flo.addRow("Double validator",e2)
                flo.addRow("Input Mask",e3)
                flo.addRow("Text changed",e4)
                flo.addRow("Password",e5)
                flo.addRow("Read Only",e6)

                self.setLayout(flo)
                self.setWindowTitle("QLineEdit Example")

        def textchanged(self,text):
                print("Changed: " + text)

        def enterPress(self):
                print("Enter pressed")

if __name__ == "__main__":
        app = QApplication(sys.argv)
        win = lineEditDemo()
        win.show()
        sys.exit(app.exec_())