Develop Reference

How do I pass variables to a PyQt class?

Before writing the Python code, I already made a ui file to made QT designer. The UI file has one Qlabel containing the values. To output an external value, I've tried, but I never could never make it. This is the My QtCode
import sys
from PyQt5.QtWidgets import *
from PyQt5 import uic
form_class = uic.loadUiType("untitled.ui")[0]
class WindowClass(QMainWindow, form_class) :
def __init__(self) :
super().__init__()
self.setupUi(self)
self.InitUI()
def InitUI(self, name):
self.hello.setText("Hello. %s"%name)
if __name__ == "__main__" :
app = QApplication(sys.argv)
myWindow = WindowClass()
myWindow.show()
app.exec_()
I want to accept the name value in if__name__=="main_" and hand it over to the part that outputs the label of the Qt class. I am not that good at English.

Sending Data from Child to Parent Window in PyQt5

What I can't do
I'm not able to send data back from a child to a parent window.
What I have
I've got a complex GUI with several windows sendíng data to child windows. Each window represents a unique Python-script in the same directory. There was no need to explicitely specify parents and childs, as the communication was always unidirectional (parent to child). However, now I need to send back data from childs to parents and can't figure out how to do this as each window (i.e. each class) has its own file.
Example
Here's a minimal example showing the base of what I want to accomplish.
What it does: win01 opens win02 and win02 triggers func in win01.
# testfile01.py
import sys
from PyQt5.QtWidgets import *
import testfile02 as t02
class win01(QWidget):
def __init__(self, parent=None):
super(win01, self).__init__(parent)
self.win02 = t02.win02()
self.button = QPushButton("open win02", self)
self.button.move(100, 100)
self.button.clicked.connect(self.show_t02)
def initUI(self):
self.center
def show_t02(self):
self.win02.show()
def func(self):
print("yes!")
if __name__ == '__main__':
app = QApplication(sys.argv)
ex = win01()
ex.show()
sys.exit(app.exec_())
##########################################################################
# testfile02.py
from PyQt5.QtWidgets import *
import testfile01 as t01
class win02(QWidget):
def __init__(self, parent=None):
super(win02, self).__init__(parent)
self.win01 = t01.win01()
self.button = QPushButton()
self.button.clicked.connect(self.win01.func)
def initUI(self):
self.center()
What I tried
Importing testfile01 in the second window always leads to the error:
RecursionError: maximum recursion depth exceeded.
Then, I tried the following approaches, but they didn't work either:
Not importing testfile01 in win02 and adjusting parent=None to different other objects
Importing testfile01 within the __init__ call of win02
Creating a signal in win02 to trigger func in win01
The Question
Is there a solution how to properly trigger func in win01 from win02?

Why are you getting RecursionError: maximum recursion depth exceeded?
You are getting it because you have a circular import that generates an infinite loop, in testfile01 you are importing the file testfile02, and in testfile02 you are importing testfile01, .... So that is a shows of a bad design.
Qt offers the mechanism of signals for objects to communicate information to other objects, and this has the advantage of non-dependence between classes that is a great long-term benefit (as for example that avoids circular import), so for that reason I think it is the most appropriate.
For this I will create the clicked signal in the class win02 that will be triggered by the clicked signal of the button, and make that clicked signal call the func:
testfile01.py
import sys
from PyQt5.QtWidgets import QWidget, QPushButton, QApplication
import testfile02 as t02
class win01(QWidget):
def __init__(self, parent=None):
super(win01, self).__init__(parent)
self.win02 = t02.win02()
self.win02.clicked.connect(self.func)
self.button = QPushButton("open win02", self)
self.button.move(100, 100)
self.button.clicked.connect(self.show_t02)
def show_t02(self):
self.win02.show()
def func(self):
print("yes!")
if __name__ == "__main__":
app = QApplication(sys.argv)
ex = win01()
ex.show()
sys.exit(app.exec_())
testfile02.py
from PyQt5.QtCore import pyqtSignal
from PyQt5.QtWidgets import QWidget, QPushButton, QVBoxLayout
class win02(QWidget):
clicked = pyqtSignal()
def __init__(self, parent=None):
super(win02, self).__init__(parent)
self.button = QPushButton("call to func")
self.button.clicked.connect(self.clicked)
lay = QVBoxLayout(self)
lay.addWidget(self.button)
I recommend you read:
https://doc.qt.io/qt-5/signalsandslots.html

Both the Widgets are independent and have no link in between.
Set win01 parent of win02.
In class win01
Replace :
self.win01 = t02.win02()
#and
self.win02.show()
with:
self.win01 = t02.win02(self)
#and
self.win01.show()
and in class win02
Replace:
self.win02 = t01.win01()
#and
self.button.clicked.connect(self.win01.func)
with:
self.win02 = self.parent()
#and
self.button.clicked.connect(self.win02.func)

pyqt5 custom dialog input popup within main window

I need to generate a custom popup input window triggered by clicking a QPushButton in my app (via clicked). It needs to get several inputs from the user of different types and then return them to the calling function inside the main window app. I have found built in functions such as QInputDialog that can do this for single specific inputs, but I can't figure out how to do this in the case of a popup that asks for several inputs of different types at once (preferably in a window designed in Qt Designer). Does anyone know how to do this?
import sys
import os
from PyQt5.QtWidgets import QMainWindow, QApplication
from PyQt5 import uic
path = os.path.dirname(__file__) #uic paths from itself, not the active dir, so path needed
qtCreatorFile = "NAME.ui" #Ui file name, from QtDesigner
Ui_MainWindow, QtBaseClass = uic.loadUiType(path + qtCreatorFile) #process through pyuic
class MyApp(QMainWindow, Ui_MainWindow): #gui class
def __init__(self):
#Set up the gui via Qt
super(MyApp, self).__init__()
self.ui = Ui_MainWindow()
self.ui.setupUi(self)
self.ui.add_button.clicked.connect(self.add_row) #add_button is QPushButton
def add_row(self):
data1, data2, data3 = #popup form to get data (types are not the same)
#do stuff with data
pass
#start app
if __name__ == "__main__":
app = QApplication(sys.argv) #instantiate a QtGui (holder for the app)
window = MyApp()
window.show()
sys.exit(app.exec_())

There is no single solution but I will give you a guide to do what you want.
If you want to get a widget with the behavior of QInputDialog you must first choose the right template, in this case a good option is Dialog with Buttons Bottom or Dialog with Buttons Right, add the components you want, position it, etc.
Then as you show your code you create a class that inherits from QDialog and then create a method where you get the results but to do so do not use show() but exec_()
path = os.path.dirname(__file__)
qtCreatorFile = "some_dialog.ui"
Ui_Dialog, _ = uic.loadUiType(os.path.join(path,qtCreatorFile))
class CustomDialog(QDialog, Ui_Dialog):
def __init__(self):
super(CustomDialog, self).__init__()
self.setupUi(self)
# set initials values to widgets
def getResults(self):
if self.exec_() == QDialog.Accepted:
# get all values
val = self.some_widget.some_function()
val2 = self.some_widget2.some_another_function()
return val1, val2, ...
else:
return None
And then use it in your function:
class MyApp(QMainWindow, Ui_MainWindow): #gui class
def __init__(self):
#Set up the gui via Qt
super(MyApp, self).__init__()
self.setupUi(self)
self.add_button.clicked.connect(self.add_row) #add_button is QPushButton
def add_row(self):
w = CustomDialog()
values = w.getResults()
if values:
data1, data2, data3 = values

I can't get my GUI to load and recognize buttons using PySide

Here is the error I am getting, which I am really confused about. My UI file which I am loading has this button name and it matches. But for some reason it doesn't seem to recognize and load it. I just tried converting this code over to PySide (it was originally PyQt). Am I doing something wrong in translating it?
Error: AttributeError: file line 25: 'swapRefGUI' object has no attribute 'swapRefBtn' #
from PySide import QtCore, QtGui, QtUiTools
import maya.cmds as cmds
class swapRefGUI(QDialog):
def __init__(self, parent=None):
QDialog.__init__(self, parent)
loader = QtUiTools.QUiLoader()
uifile = QtCore.QFile('C:\Scripts\swapRef.ui')
uifile.open(QtCore.QFile.ReadOnly)
ui = loader.load(uifile, parent)
uifile.close()
self.setFixedSize(400, 300)
self.swapRefBtn.clicked.connect(self.swapRefBtn_clicked)
self.closeBtn.clicked.connect(self.close)
def swapRefBtn_clicked(self):
pass
if __name__ == "__main__":
#app = QApplication(sys.argv)
app = QApplication.instance()
if app is None:
app = QApplication(sys.argv)
myGUI = swapRefGUI(None)
myGUI.show()
sys.exit(app.exec_())

Right now you are trying to access swapRefBtn through the class instance swapRefGUI, but you actually need to access it through the ui variable where you load. The 2nd argument of loader.load should also be self to display the qt gui in your window. There's also a few instances where you are trying to access objects from PySide like QDialog, when it should be QtGui.QDialog (because of the way you imported PySide module).
Here's some code that worked with a ui file.
from PySide import QtCore, QtGui, QtUiTools
import maya.cmds as cmds
class swapRefGUI(QtGui.QDialog):
def __init__(self, parent=None):
QtGui.QDialog.__init__(self, parent)
loader = QtUiTools.QUiLoader()
uifile = QtCore.QFile('C:\Scripts\swapRef.ui')
uifile.open(QtCore.QFile.ReadOnly)
self.ui = loader.load(uifile, self) # Qt objects are inside ui, so good idea to save the variable to the class, 2nd arg should refer to self
uifile.close()
self.setFixedSize(400, 300)
self.ui.swapRefBtn.clicked.connect(self.swapRefBtn_clicked) # Need to access button through self.ui
#self.ui.closeBtn.clicked.connect(self.close) # This needs to have an existing function in the class or it will crash when executing
def swapRefBtn_clicked(self):
print 'WORKS'
myGUI = swapRefGUI()
myGUI.show()

To show PyQt main window inside a function

I am trying to write a python script to an application like matplotlib.
I need a function call to show the Qt main window. How do I do this?
class MainWindow(QtGui.QMainWindow):
def __init__(self,parent=None):
super(MainWindow, self).__init__(parent)
self.setupUi(self)
self.numbers = 4
...
app = QtGui.QApplication(sys.argv)
dmw = DesignerMainWindow()
dmw.show()
sys.exit(app.exec_()) #this works, but pops the window right away
I want to be able to call the window when I wish instead. (Something like this)
def newWin():
app = QtGui.QApplication(sys.argv)
dwm = MainWindow()
sys.exit(app.exec_())
return dwn
a = newWin() # application is created now
a.numbers = 10 # do something
a.show() # should pop me the window now
EDIT : Pasting solution thanks to jadkik94
class App(QtGui.QApplication):
def __init__(self, args):
QtGui.QApplication.__init__(self,args)
self.window = MainWindow()
def doSomething(self, ii):
self.window.numbers = ii
def show(self):
self.window.show()
sys.exit(self.exec_())
a = App(sys.argv)
a.doSomething(12) #updates numbers alternately a.window.numbers = 12
a.show() #pops the window!

When used inside a function, the window does not show. The problem is simple: the window is garbage collected because it is defined inside the scope of the function, and then not used anymore, so Python sees it as "garbage" and deletes the object.
The best way I found of avoiding that is having an application class that will hold references to all the windows you want to show. So you can either have a regular class do that for you, or subclass the QtGui.QApplication if you can make use of it otherwise too. I would go for the second option.
Another option, if you really don't want to be using a class, is to set it to a global variable, and that will usually prevent it from being garbage-collected by Python.

Is this what you want:
import sys
from PyQt4 import QtGui
class Example(QtGui.QWidget):
def __init__(self):
super(Example, self).__init__()
self.initUI()
def initUI(self):
self.setGeometry(300, 300, 250, 150)
self.setWindowTitle('Icon')
self.show()
def main():
app = QtGui.QApplication(sys.argv)
ex = Example()
sys.exit(app.exec_())
a = main()
a.show()