Question

I’m having a problem trying to do a very simple user interface. I made my UI with Qt Designer, and then with pyuic4 I got my python code. Then I programmed the function I needed, and compiled with Eclipse IDE.

The code I got from pyuic4 is:

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'Dni.ui'
#
# Created: Sat Apr 14 02:44:34 2012
#      by: PyQt4 UI code generator 4.9.1
#
# WARNING! All changes made in this file will be lost!
from PyQt4 import QtCore, QtGui
try:
    _fromUtf8 = QtCore.QString.fromUtf8
except AttributeError:
    _fromUtf8 = lambda s: s

class Ui_Dialog(object):
    def setupUi(self, Dialog):
        Dialog.setObjectName(_fromUtf8("Dialog"))
        Dialog.resize(371, 217)
        Dialog.setMinimumSize(QtCore.QSize(371, 217))
        self.layoutWidget = QtGui.QWidget(Dialog)
        self.layoutWidget.setGeometry(QtCore.QRect(30, 30, 311, 151))
        self.layoutWidget.setObjectName(_fromUtf8("layoutWidget"))
        self.gridLayout = QtGui.QGridLayout(self.layoutWidget)
        self.gridLayout.setMargin(0)
        self.gridLayout.setObjectName(_fromUtf8("gridLayout"))
        self.horizontalLayout = QtGui.QHBoxLayout()
        self.horizontalLayout.setObjectName(_fromUtf8("horizontalLayout"))
        self.label = QtGui.QLabel(self.layoutWidget)
        self.label.setObjectName(_fromUtf8("label"))
        self.horizontalLayout.addWidget(self.label)
        self.entrada = QtGui.QLineEdit(self.layoutWidget)
        self.entrada.setObjectName(_fromUtf8("entrada"))
        self.horizontalLayout.addWidget(self.entrada)
        self.gridLayout.addLayout(self.horizontalLayout, 0, 0, 1, 1)
        self.boton = QtGui.QPushButton(self.layoutWidget)
        self.boton.setObjectName(_fromUtf8("boton"))
        self.gridLayout.addWidget(self.boton, 1, 0, 1, 1)
        self.horizontalLayout_2 = QtGui.QHBoxLayout()
        self.horizontalLayout_2.setObjectName(_fromUtf8("horizontalLayout_2"))
        self.label_3 = QtGui.QLabel(self.layoutWidget)
        self.label_3.setObjectName(_fromUtf8("label_3"))
        self.horizontalLayout_2.addWidget(self.label_3)
        self.salida = QtGui.QLineEdit(self.layoutWidget)
        self.salida.setObjectName(_fromUtf8("salida"))
        self.horizontalLayout_2.addWidget(self.salida)
        self.gridLayout.addLayout(self.horizontalLayout_2, 2, 0, 1, 1)
        self.retranslateUi(Dialog)
        QtCore.QMetaObject.connectSlotsByName(Dialog)

    def retranslateUi(self, Dialog):
        Dialog.setWindowTitle(QtGui.QApplication.translate("Dialog", "Dialog", None, QtGui.QApplication.UnicodeUTF8))
        self.label.setText(QtGui.QApplication.translate("Dialog", "Introduzca su DNI", None, QtGui.QApplication.UnicodeUTF8))
        self.boton.setText(QtGui.QApplication.translate("Dialog", "Hallar NIF", None, QtGui.QApplication.UnicodeUTF8))
        self.label_3.setText(QtGui.QApplication.translate("Dialog", "NIF:", None, QtGui.QApplication.UnicodeUTF8))


if __name__ == "__main__":
    import sys
    app = QtGui.QApplication(sys.argv)
    Dialog = QtGui.QDialog()
    ui = Ui_Dialog()
    ui.setupUi(Dialog)
    Dialog.show()
    sys.exit(app.exec_())

And the code I made with the function I need:

from Dni import Ui_Dialog
from PyQt4 import QtCore, QtGui

LETRADNI = {0:'T', 1:'R', 2:'W', 3:'A', 4:'G', 5:'M', 6:'Y', 7:'F', 8:'P', 9:'D', 10:'X', 11:'B', 12:'N',
            13: 'J', 14:'Z', 15:'S', 16:'Q', 17:'V', 18:'H', 19:'L', 20:'C', 21:'K', 22:'E'}


# Se hereda de la clase QtGui.QMainWindow
class Principal(QtGui.QMainWindow):
    # Se define el constructor de la clase __init__
    def __init__(self):
        # Se llama al constructor de la clase padre
        QtGui.QMainWindow.__init__(self)

        # Se crea la instancia de Ui_Dialog
        self.ventana = Ui_Dialog()
        self.ventana.setupUi(self)

        # Se conectan las señales con los slots
        self.connect(self.ventana.boton,QtCore.SIGNAL('clicked()'), self.letradni)


def Calcula_letra_dni(dni):
    '''Función Calcula_letra_dni:

        Funcionamiento:

            La función recibe el valor entero dni. Posteriormente calculará el resto de la división
            por 23. Éste número se buscará en el diccionario 'LETRADNI' para obtener la letra correspondiente
            a ese DNI.

        Argumentos

            dni -- número del documento nacional de identidad (int)

        Devuelve:

            Una cadena (string) -- DNI + letra preparado para salida por pantalla
    '''
    #if len(str(dni))>8 & len(str(dni))<7:
    #    raise ValueError('El dni debe tener entre 7 y 8 cifras')

    num_letra = dni % 23.0

    letra = LETRADNI[num_letra]

    return '{0}-{1}'.format(dni,letra)


def letradni(self):
    self.ventana.salida.setText(Calcula_letra_dni(self.ventana.entrada.text()))

The first one compiles and runs, it shows my ui perfectly.

Compiling the second one I get an error that says:

Description                                 Resource  Path  Location   Type
Undefined variable from import: QString Dni.py    /Dni  line 18    PyDev Problem

Can anyone help me?

Thanks in advance.

Answer 1

First off, I think your actual listed problem is related to Eclipse, pydev, and your projects PYTHONPATH. Review this to make sure you have properly set up everything and included PyQt4 in your pythonpath:
http://popdevelop.com/2010/04/setting-up-ide-and-creating-a-cross-platform-qt-python-gui-application/

After that, you seem to have some problems with your code beyond what you have mentioned…

First you define Principal class, then a Calcula_letra_dni function, but then you are defining what looks like a class instance method letradni which should be part of Principal:

class Principal(QtGui.QMainWindow):
    # Se define el constructor de la clase __init__
    def __init__(self):
        ...

    def letradni(self):
        ...


def Calcula_letra_dni(dni):
    ...

Then it looks like you will raise an exception when you try to do math on a string (thanks @Avaris) and float:
num_letra = dni % 23.0

You should probably convert that string to a float first: num_letra = float(dni) % 23.0

And finally, I think you also forgot to define a main for your application. You have the one that is autogenerated in your Dni.py, but you didn’t write one for your actual entry point script:

if __name__ == "__main__":
    import sys
    app = QtGui.QApplication(sys.argv)
    form = Principal()
    form.show()
    sys.exit(app.exec_())