How to Properly Structure Python Functions with Qt Designer

Struggling to run functions in separate files using Qt Designer and Python? Discover how to resolve common issues and optimize your GUI development workflow with this comprehensive guide!
---

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Properly Structure Python Functions with Qt Designer: A Beginner's Guide

Creating a graphical user interface (GUI) can be an exciting journey, especially when using powerful tools like Qt Designer in combination with Python. However, as a beginner, you may face challenges, such as separating functionality into different files. One common problem is the error message: Ui_MainWindow' object has no attribute 'fillContactList'. This guide will guide you through the steps to effectively structure your code and avoid such errors.

Understanding the Problem

When designing a GUI with Qt Designer, you often end up with a generated code file. Any changes made to the design in Qt Designer can overwrite your custom code. Thus, it’s important to structure your application in a way that allows you to keep your function definitions separate from UI code.

In this case, you are trying to call a method (fillContactList) that is not found within the context of the UI object. This is likely due to a misunderstanding of how to properly instigate and interact with the UI class in PyQt/PySide.

The Solution: Code Structure Simplified

Let’s break down how to solve the problem step-by-step.

Step 1: Rename the Class

First, it’s essential to adopt proper naming conventions. Your main window class should be renamed from mainwindow to MainWindow. This aligns with Python's PEP 8 style guidelines which suggest using CapitalizedWords for class names.

Step 2: Subclassing Correctly

Your MainWindow class should only inherit from QMainWindow, not from both Ui_MainWindow and QMainWindow as done previously. The Ui_MainWindow class is not meant to be directly subclassed for the purpose of accessing its widgets.

Step 3: Setup the User Interface

Create an instance of Ui_MainWindow within your MainWindow class and set it up appropriately. The widgets designed in Qt Designer become attributes of this instance. The code should look as follows:

[[See Video to Reveal this Text or Code Snippet]]

This ensures that you are using the correct context to call UI elements.

Step 4: Accessing Widgets

[[See Video to Reveal this Text or Code Snippet]]

Step 5: Implement the Class

Here is a reorganized version of your code to illustrate these concepts:

[[See Video to Reveal this Text or Code Snippet]]

Final Thoughts and Additional Tips

Separate Logic from Interface: Keep business logic in separate functions or files when necessary.

Testing: Regularly test your application. Run your code after each structural change to catch errors early.

By following these steps, you can effectively structure your PyQt/PySide projects, avoid common pitfalls, and create a seamless experience in your app development journey. Happy coding!