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PyQt5 Controller cannot access children names

for a python program I created a gui with QtDesigner. Inside my program the gui is initiated and calls the .ui-file to implement content.
The gui class object is than given to a Controller, and here it gets tricky:
Instead of one Controller, there are a main controller and some sub-controller for different parts of the gui. The main Controller does one or two general things and than hands over different parts of the gui to different sub controller.
See the following example for better understanding:
import Controller # import the folder with the controller
def __init__(self, window):
self.window = window # self.window is the handed over gui
self.sub_controls()
def sub_controls(self):
Controller.Sub_Controller_1(window = self.window.part_1)
Controller.Sub_Controller_2(window = self.window.part_2)
Controller.Sub_Controller_3(window = self.window.part_3)
...
The sub-Controller is set up like this:
def __init__(self, window):
self.window = window
... # do stuff:
-----------------------------------------
by trying to call a widget in this Sub-Controller (lets say its a label called timmy), i get an error:
self.window.timmy.setVisible(False)
AttributeError: 'QWidget' object has no attribute 'timmy'
but by using the children()-Method, which returns a list of all children in the gui, I may access this label:
self.window.children()[1].setVisible(False)
This works well and hides timmy.
By trying to do this in the main Controller, it works fine as usual:
self.window.timmy.setVisible(False) # works fine here
I also tried to save the sub-controller object like this:
def sub_controls(self):
self.save_part_1 = Controller.Sub_Controller_1(window = self.window.part_1)
but this doesn't work.
Does any one have a suggestion, how I could solve this Problem?
Sure, I couldt access just all widgets with the children()-method-list, but this is laborious because of the great amount of widgets. Same thing applies to reassigning every child.
PS:
Unfortunately I cannot show you the original Code due to company guidelines.

Ok so I figured out, that the tree Structure of in each other nested widgets has nothing to do with the naming of the widgets. For example:
MainWindow
->centralWidget
->otherWidget
->Button
In this you can address "Button" with self.Button, because (how I believe) the name is saved in MainWindow-Level. If you cut out "otherWidget", the QPushButton in it still exists, but cannot addressed by name.
So it's not possible to just hand over a part of your Gui to a Handler, at least if it's build with QtDesigner.
My Solution for me to the original Problem is to hand over the complete Gui to every sub handler:
def __init__(self, window):
self.window = window # self.window is the handed over gui
self.sub_controls()
def sub_controls(self):
Controller.Sub_Controller_1(window = self.window)
Controller.Sub_Controller_2(window = self.window)
# Controller.Sub_Controller_3(window = self.window.part_3) # before

Tkinter Widget References

I have a question about how to properly address widget attributes from outside the GUI main loop. Here is the gist of my project: I have an HMI, and it runs in its own thread. Outside of the HMI, there will be another thread that is collecting data and writing to hardware. I stripped out a bunch of stuff to create a basic example so you can see what I mean. It consists of a main window, a frame where the operator can select manual or auto, and a notebook that will display temperature probe data. In the real world, there will be varying numbers of probes and additional attributes, which is why I instantiate the probes at the top of the script. In real life, this would come from a SQL database and the GUI would be built dynamically based on database properties.
from tkinter import *
import tkinter as tk
from tkinter import ttk
from threading import Thread
from time import sleep
import random
wProbes= {1: {'Title': 'Indoors','Temperature':0,'MainObject':'','TempLabel':''},2: {'Title': 'Outdoors','Temperature':0,'Object':''}}
controlTemplate={'State':0,'On':0, 'Off':0}
systemControl = {'Auto':controlTemplate,'Manual':controlTemplate}
def gui():
class SystemOperation(tk.LabelFrame):
def __init__(self,parent):
super().__init__(parent)
self.config(text='System Operation',labelanchor='n',bd=2,highlightbackground='black',relief= 'solid',font=("arial", 20))
self.place(width=500, height=900,x=150,y=100)
def autoModeClick():
self.bAutoMode.configure(background='green')
self.bManualMode.configure(background='white')
systemControl['Auto']['State'] = 1
systemControl['Manual']['State'] = 0
def manualModeClick():
self.bManualMode.configure(background='green')
self.bAutoMode.configure(background='white')
systemControl['Auto']['State'] = 0
systemControl['Manual']['State'] = 1
self.bAutoMode = Button(self, text='Auto', background='green', command=autoModeClick)
self.bAutoMode.place(x=100, y=100, width=70)
self.bManualMode = Button(self, text='Manual', command=manualModeClick)
self.bManualMode.place(x=100, y=150, width=70)
class TemperatureProbe(tk.LabelFrame):
def __init__(self,parent,inst):
super().__init__(parent)
self.config(text=wProbes[inst]['Title'],labelanchor='n',bd=2,highlightbackground='black',relief= 'solid',font=("arial", 20))
self.place(width=500, height=300)
self.currentTemp=0
self.actTemp=Label(self,text='Temperature= %d F'%self.currentTemp,width=20)
self.actTemp.place(relx=.5, y=20, anchor='center')
self.pack_propagate(0)
wProbes[inst]['TempLabel']=self.actTemp
class probeNotebook(ttk.Notebook):
def __init__(self,parent):
super().__init__(parent)
self.place(x=900,y=100,width=800,height=700)
for t in sorted(wProbes.keys()):
tabName = wProbes[t]['Title']
self.tabFrame = tk.Frame(self, width=700, height=900, bg='white', borderwidth=2, relief='solid')
self.add(self.tabFrame, text=' %s '%tabName)
self.pFB=TemperatureProbe(self.tabFrame,t)
self.pFB.place(x=100, y=20)
wProbes[t]['MainObject']=self.pFB
class MainWindow(tk.Tk):
def __init__(self):
super().__init__()
self.geometry("800x800")
self.title('Test Window')
SystemOperation(self)
probeNotebook(self)
if __name__=="__main__":
app=MainWindow()
app.mainloop()
threadGUI = Thread(target=gui)
threadGUI.start()
while 1:
#A bunch of stuff will be happening here that interfaces with external hardware
if wProbes[1]['MainObject']!='':
randInt=random.randint(10,200)
wProbes[1]['TempLabel'].config(text='Temperature= %d F'%randInt)
wProbes[2]['TempLabel'].config(text='Temperature= %d F' % (randInt+200))
sleep(.5)
So, you can see that a notebook is created, and the tabs are then created based on the number of probes in the probe dictionary. Also in the probe dictionary, I set a reference to the probe container, and then the probe temperature label. If you run the code, you can see the temperatures change correctly based on the probe instances with a test random int.
But what I was really hoping to do is just use the probe MainObject reference and address its child widgets that way, i.e. wProbes[1]['MainObject'].actTemp, because in reality the probe container will have more widgets such as limits and setpoints and warnings. But if creating individual references is the correct way, I'm good with that too. Am I on the right track?
Another thing I wondered about as I go forward is how I can separate the GUI from the process script completely. Imagine the GUI as a standalone app, and a second app that acts like a server and does the heavy lifting and communicates with the GUI. Any basic hints on doing this? I'll do the work in figuring it out, but if you push me in the right direction I'd appreciate it.
Also, if there are criticisms of my project approach in general, I'm all ears. I've done quite a bit of python programming, but this is my first tkinter attempt. Thanks!
(Note: I hope it formatted correctly. I just copied and pasted into my ide, and it was fine. Worst case would be that the indentation is wrong in a couple of places when copied, but give it a try.)

Delete all from TkInter Canvas and put new items while in mainloop

The goal is to achieve different "screens" in TkInter and change between them. The easiest to imagine this is to think of a mobile app, where one clicks on the icon, for example "Add new", and new screen opens. The application has total 7 screens and it should be able to change screens according to user actions.
Setup is on Raspberry Pi with LCD+touchscreen attached. I am using tkinter in Python3. Canvas is used to show elements on the screen.
Since I am coming from embedded hardware world and have very little experience in Python, and generally high-level languages, I approached this with switch-case logic. In Python this is if-elif-elif...
I have tried various things:
Making global canvas object. Having a variable programState which determines which screen is currently shown. This obviously didn't work because it would just run once and get stuck at the mainloop below.
from tkinter import *
import time
root = Tk()
programState = 0
canvas = Canvas(width=320, height=480, bg='black')
canvas.pack(expand=YES, fill=BOTH)
if(programState == 0):
backgroundImage = PhotoImage(file="image.gif")
canvas.create_image(0,0, image=backgroundImage, anchor=NW);
time.sleep(2)
canvas.delete(ALL) #delete all objects from canvas
programState = 1
elif(programState == 1):
....
....
....
root.mainloop()
Using root.after function but this failed and wouldn't show anything on the screen, it would only create canvas. I probably didn't use it at the right place.
Trying making another thread for changing screens, just to test threading option. It gets stuck at first image and never moves to second one.
from tkinter import *
from threading import Thread
from time import sleep
def threadFun():
while True:
backgroundImage = PhotoImage(file="image1.gif")
backgroundImage2 = PhotoImage(file="image2.gif")
canvas.create_image(0,0,image=backgroundImage, anchor=NW)
sleep(2)
canvas.delete(ALL)
canvas.create_image(0,0,image=backgroundImage2, anchor=NW)
root = Tk()
canvas = Canvas(width=320, height=480, bg='black')
canvas.pack(expand=YES, fill=BOTH)
# daemon=True kills the thread when you close the GUI, otherwise it would continue to run and raise an error.
Thread(target=threadFun, daemon=True).start()
root.mainloop()
I expect this app could change screens using a special thread which would call a function which redraws elements on the canvas, but this has been failing so far. As much as I understand now, threads might be the best option. They are closest to my way of thinking with infinite loop (while True) and closest to my logic.
What are options here? How deleting whole screen and redrawing it (what I call making a new "screen") can be achieved?

Tkinter, like most GUI toolkits, is event driven. You simply need to create a function that deletes the old screen and creates the new, and then does this in response to an event (button click, timer, whatever).
Using your first canvas example
In your first example you want to automatically switch pages after two seconds. That can be done by using after to schedule a function to run after the timeout. Then it's just a matter of moving your redraw logic into a function.
For example:
def set_programState(new_state):
global programState
programState = new_state
refresh()
def refresh():
canvas.delete("all")
if(programState == 0):
backgroundImage = PhotoImage(file="image.gif")
canvas.create_image(0,0, image=backgroundImage, anchor=NW);
canvas.after(2000, set_programState, 1)
elif(programState == 1):
...
Using python objects
Arguably a better solution is to make each page be a class based off of a widget. Doing so makes it easy to add or remove everything at once by adding or removing that one widget (because destroying a widget also destroys all of its children)
Then it's just a matter of deleting the old object and instantiating the new. You can create a mapping of state number to class name if you like the state-driven concept, and use that mapping to determine which class to instantiate.
For example:
class ThisPage(tk.Frame):
def __init__(self):
<code to create everything for this page>
class ThatPage(tk.Frame):
def __init__(self):
<code to create everything for this page>
page_map = {0: ThisPage, 1: ThatPage}
current_page = None
...
def refresh():
global current_page
if current_page:
current_page.destroy()
new_page_class = page_map[programstate]
current_page = new_page_class()
current_page.pack(fill="both", expand=True)
The above code is somewhat ham-fisted, but hopefully it illustrates the basic technique.
Just like with the first example, you can call update() from any sort of event: a button click, a timer, or any other sort of event supported by tkinter. For example, to bind the escape key to always take you to the initial state you could do something like this:
def reset_state(event):
global programState
programState = 0
refresh()
root.bind("<Escape>", reset_state)

Displaying only one frame at a time in tkinter

I've been struggling with this for a while. I think I'm missing some simple piece of information and I hope you guys can help clear this up for me.
I'm trying to get tkinter to display different frames which I will eventually place widgets inside of. Here's what I did:
I've made a class that is supposed to initialize the window and make all the different frames the program will run.
I've made a separate class for each frame(I'm intending to have variables associated with the different classes when the program is done), and assigned a variable that will start that class up and make it run it's init function
I ended the StartUp class by telling it to tkraise() the frame I want displayed, and that's where things stop working correctly.
I set each frame to a different color, so when you run this program you will see that they split the screen space up instead of one being raised to the top. What am I missing?
One last point, I am purposely trying to spell everything out in my program, I learn better that way. I left it so I have to type tkinter.blah-blah-blah in front of each tkinter command so I can recognize them easily, and I decided not to have my classes inherit Frame or Tk or anything. I'm trying to understand what I'm doing.
import tkinter
class StartUp:
def __init__(self):
self.root = tkinter.Tk()
self.root.geometry('300x300')
self.container = tkinter.Frame(master=self.root, bg='blue')
self.container.pack(side='top', fill='both', expand=True)
self.page1 = Page1(self)
self.page2 = Page2(self)
self.page1.main_frame.tkraise()
class Page1():
def __init__(self, parent):
self.main_frame = tkinter.Frame(master=parent.container, bg='green')
self.main_frame.pack(side='top', fill='both', expand=True)
class Page2():
def __init__(self, parent):
self.main_frame = tkinter.Frame(master=parent.container, bg='yellow')
self.main_frame.pack(side='top', fill='both', expand=True)
boot_up = StartUp()
boot_up.root.mainloop()

When you do pack(side='top', ...), top doesn't refer to the top of the containing widget, it refers to the top of any empty space in the containing widget. Page initially takes up all of the space, and then when you pack Page2, it goes below Page1 rather than being layered on top of it.
If you are using the strategy of raising one window above another, you need to either use grid or place to layer the widgets on top of each other. The layering is something pack simply can't do.
Your other choice is to call pack_forget on the current window before calling pack on the new windowl

tkinter and GUI programming methods

Hopefully this doesn't fall under "general discussion topic", since I'd like it to be more about resolving these issues in an efficient manner than a giant debate about which general approach to GUI programming is the absolute best.
So I've started some GUI programming with tkinter and long story short my code is getting pretty ugly pretty quickly. I'm trying to create a tile-based map editor for a video game. My main issues seem to be:
the inability of callbacks to return values.
the inability to transfer data between windows easily.
I assume that the reason I see these as issues is because I'm using functions a lot more than I'm using classes. For instance, my "load tileset" window is handled entirely functionally: Clicking the menu option in the main window calls the function that loads the new window. From within that window, I create an open file dialog when looking for the image, and modify the canvas displaying the image when I press the enter key (so that it draws the appropriate grid over the image). function function function.
What looks like really bad practice to me is the inclusion of extra arguments to compensate. For example, when I create a tileset, the instance of the TileSet class created should be sent back to the main window where the appropriate information can be displayed. I have a list of loaded tilesets as a global variable (even more bad practice: Everything dealing with my root window is in the global scope! yay!), and because callback functions don't return values, I pass that list as an argument to my "load tileset window" function, which then passes the argument to the create tileset function (called when you click the appropriate button in the window), where it's actually needed so that I can add my newly created tileset to the list. Passing arguments through a function 'hierarchy' like that seems like a horrible idea. It gets confusing, it's horrible for writing modular code, and just generally seems unnecessary.
My attempt at fixing the problem would be to write a class representing the whole GUI, and custom made window classes (that the GUI class can create and reference) that can actually store relevant data. That should take care of issues with transferring data between windows. Hopefully it would cut down on my gratuitous use of lambda functions in callbacks as well.
But I'm wondering: is this the best way? Or at least close? I'd rather not start rewriting and then end up with another system that's just sloppy and confusing in a different way. I know my methods are bad, but I don't really know what the best approach would be. I'm getting a lot of advice on how to do specific things, but none on how to structure the program as a whole. Any help would be greatly appreciated.

It sounds like you're trying to create a GUI that acts procedurally, which won't work. GUIs aren't procedural, their code doesn't run linearly where functions call callbacks which return values. What you're asking isn't unique to tkinter. This is the nature of event based GUI programming -- callbacks can't return anything because the caller is an event rather than a function.
Roughly speaking, you must use a global object of some sort to store your data. Typically this is called the "Model". It can be a global variable, or it might be a database, or it can be an object of some sort. In any case, it must exist "globally"; that is, it must be accessible to the whole GUI.
Often, this access is provided by a third component called a "Controller". It is the interface between the GUI (the "View") and the data (the "Model"). These three components make up what is called the model-view-controller pattern, or MVC.
The model, view and controller don't have to be three different objects. Often, the GUI and the controller are the same object. For small programs this works quite well -- the GUI components talk directly to your data model.
For example, you could have a class that represents a window which inherits from Tkinter.Toplevel. It can have an attribute that represents the data being edited. When the user selects "New" from a main window, it does something like self.tileset = TileSet(filename). That is, it sets the attribute named tileset of the GUI object named self to be an instance of the TileSet class specific to the given filename. Later functions that manipulate the data use self.tileset to access the object. For functions that live outside the main window object (for example, a "save all" function from the main window) you can either pass this object as an argument, or use the window object as the controller, asking it to do something to its tileset.
Here's a brief example:
import Tkinter as tk
import tkFileDialog
import datetime
class SampleApp(tk.Tk):
def __init__(self, *args, **kwargs):
tk.Tk.__init__(self, *args, **kwargs)
self.windows = []
menubar = tk.Menu(self)
self.configure(menu=menubar)
fileMenu = tk.Menu(self)
fileMenu.add_command(label="New...", command=self.new_window)
fileMenu.add_command(label="Save All", command=self.save_all)
menubar.add_cascade(label="Window", menu=fileMenu)
label = tk.Label(self, text="Select 'New' from the window menu")
label.pack(padx=20, pady=40)
def save_all(self):
# ask each window object, which is acting both as
# the view and controller, to save it's data
for window in self.windows:
window.save()
def new_window(self):
filename = tkFileDialog.askopenfilename()
if filename is not None:
self.windows.append(TileWindow(self, filename))
class TileWindow(tk.Toplevel):
def __init__(self, master, filename):
tk.Toplevel.__init__(self, master)
self.title("%s - Tile Editor" % filename)
self.filename = filename
# create an instance of a TileSet; all other
# methods in this class can reference this
# tile set
self.tileset = TileSet(filename)
label = tk.Label(self, text="My filename is %s" % filename)
label.pack(padx=20, pady=40)
self.status = tk.Label(self, text="", anchor="w")
self.status.pack(side="bottom", fill="x")
def save(self):
# this method acts as a controller for the data,
# allowing other objects to request that the
# data be saved
now = datetime.datetime.now()
self.status.configure(text="saved %s" % str(now))
class TileSet(object):
def __init__(self, filename):
self.data = "..."
if __name__ == "__main__":
app = SampleApp()
app.mainloop()