CRUD for Python Objects

[Paul Hermans]

I am brand new to pyQt and so far finding it incredibly difficult to understand how to create a basic application that does the following:

1. Load a YAML file, storing data in python objects
2. Display the data in a TreeView and allow the user to Add/Edit/Delete the data
3. Write the Addes/Edited/Deleted data back out to the YAML file so it is available next time

I made a few python objects to represent the data.

Here are the python definitions of the classes that get used when reading the YAML file

class Student:
    def __init__(self, last_name, first_name, email):
        self.last_name = last_name
        self.first_name = first_name
        self.email = email

    def __str__(self):
        return self.last_name + ", " + self.first_name

    def __repr__(self):
        return self.__str__()

class Course():
    def __init__(self, name, teacher_dir, student_dir, root_dir):
        self.name = name
        self.teacher_dir = teacher_dir
        self.student_dir = student_dir
        self.root_dir = root_dir
        self.students = []

The specific properties of a Course and a Student don't really matter, except that a Course contains a list of Students.

How do I display this in a TreeView (or is there a better widget) and how do I make it so that a user can Add/Edit/Delete?

Add - I envision opening a dialog to add a class....would have basic properties and a way to subsequently add/edit/delete students

Edit - Same dialog as Add, just need to "connect" it to the original object and update that

Delete - Assume Course is selected and then delete button pressed.....so need to figure out which Course object to delete.

I tried reading about subclassing but couldn't find a clear explanation of which class to Subclass....and no real examples either.

Can someone help me get the ball rolling?

PS - I am using MacOsx

[JonB]

@Paul-Hermans
Indeed the most appropriate view for this would be QTreeView. This requires a backing model. Your Courses will be the nodes and your Students will be the leaves.

You should look at Qt examples: Simple Tree Model Example shows a simpler, non-editable example, while Editable Tree Model Example extends this to a fully editable model. That will provide the facilities you seek.

[Paul Hermans]

@JonB Thank you!
I somehow missed that editable example. It looks like it should get me going so I appreciate your pointing it out!

[Paul Hermans]

My C++ is pretty rusty so finding it hard to follow and wondering if there is a python version of that example?

Specifically, I think that both the TreeItem and TreeModel class are "custom" classes but the names mean nearly nothing to me. I get that they are used to store items in the tree etc, but I have no idea where the class that has actual properties that I want to use/display in the tree view is defined and what it is called. ....I am sure it is because I am brand new to Qt but finding this example very difficult to follow.

Any help would be welcome.

[JonB]

@Paul-Hermans
I don't think there is any Python version. https://doc.qt.io/qtforpython/overviews/qtwidgets-itemviews-editabletreemodel-example.html is that example in the PySide2 documentation, and as you can see the code is still in C++! :) I think that is the case for a lot of Qt examples.

Both TreeItem and TreeModel are indeed custom classes in that project. Indeed, if a class name does not start with Q... it's not a Qt-inbuilt! But the sample code reference page shows you all the code for them, and explains each bit.

You might Google for e.g. python custom qtreeview code. I came across https://stackoverflow.com/questions/17278182/qtreeview-with-custom-items. No idea if it's good/relevant, but I see it manipulates index.internalPointer(). Might help you to look at that Python code?