Django Rest Framework

Content description:
In this post I'll describe how to create a ModelViewSet based on the created Warehouse model. Then I'll describe how to create a serializer for the given model. I'll describe how to create custom permissions for the created ViewSet. Finally I'll make tests for the created API.

First, I make simple Warehouse model with foreign key - a client (the warehouse owner).

     
from django.db import models
from users.models import ContractUser


class Warehouse(models.Model):
    warehouse_name = models.CharField(max_length=15, unique=True)
    warehouse_info = models.TextField(max_length=100)
    client = models.ForeignKey(ContractUser, on_delete=models.CASCADE)

    def __str__(self):
        return self.warehouse_name

Django - new user model & manager

Content description:
In this post I'll describe how to create your own user model in Django.
Then I'll test the model and manager I created.

First, I create a new application called users.

     
python manage.py startapp users

In the models.py file, I create a custom user that inherits from the AbstractUser class. I add a checkbox in the profile so that a user can be a client or a contractor. A client issues delivery orders to warehouses, and a contractor accepts them.

Reportlab - creating PDF files

Content description:

Reportlab - generating a PDF on the server

Solved issue: How to generate a pdf file with order details and reservation barcode without saving the file to the server.

Car manager CRUD app - part IV

Content description:
This is the date picker class for the project.
You are free to use it in your projects (MIT license).

 

The date picker window is an instance of the tk.Toplevel class. I blocked the widgets in the parent window until the date picker window was closed (grab_set() function). The following lines describe the position of the date picker window relative to its parent window. Then an instance of the Calendar class is set up and dp_frame variable was set to hold an instance of the tk.Frame class. Finally, the create_cal_ui() method arranges the widgets in the window.

Car manager CRUD app - part III

Content description:
In the current post I am adding search box methods (for focus-in, focus-out and to handle text entered into the search box).
I define methods that display windows for creating a new car and for displaying repairs.

 

The methods for handling the search field are: on_entry_in(), on_entry_out() and on_entry_return().

Car manager CRUD app - part II

Content description:
In the current post, I create a GUI .
I define the main program window along with the menu bar, toolbar and search box.
I create methods to display all vehicles using a Treeview element, to remove a vehicle and to mark a car as sold.

 

The car_manager.py file contains the CarManager class. This is a class that inherits from the Frame class from the Tkinter library

When you create an instance of the CarManager class, an instance of the Helper class is created. Then the window name and application icon are set. A shortcut key for exiting the application has been set (Ctrl+x triggers the close_app() method).

Car manager CRUD app - part I

Content description:
In the current post, I create a Car class that describes the user's vehicles. The class method allows you to easily create instances using a list.
Additionally, I create a file containing SQL code that creates tables in the database and CRUD methods.

 

In this post, I will describe a simple Python GUI application for recording car repair notes.

No ORM, just simple Python classes with a Tkinter GUI and a bit of SQL (SQLite).

You can download the project code from my Github repository

First, I create a car.py file containing a class describing vehicles.

Abstract classes in Python

Abstract classes are intended to abstract functionality that will then be implemented in classes that inherit from the abstract class.

The following classes will inherit from the abstract Person class: Intern and Employee

Attempting to create an instance from the abstract Person class will result in a TypeError exception being thrown.

Additionally, not implementing all abstract methods in a child class causes a TypeError exception.

Property decorator

The concept of object-oriented programming is related to the concept of encapsulation, i.e. hiding class fields and making only public methods (public API) available to read or change the values of these fields.

Python does not support access modifiers. Using private variables like: _variable is just a matter of convention.
However, you can check the validity of the data using the property decorator.

Based on the Employee class code, let's assume that we want to verify the entered telephone number. We would like to check whether it has the appropriate number of digits and does not contain characters that are not digits.

Basics of Exception Handling in Python

Content description:

1. Python exception handling
2. Hierarchy of exceptions
3. Optional blocks: else and finally

 

Errors that show up during the execution of the program and are not syntax errors belong to the so-called exceptions.

You can handle these exceptions by putting code that can cause an exception in a try block, and the code to handle the exception in the except block: