Managing Payments and Orders

In the previous chapter, you created a basic online shop with a product catalog and a shopping cart. You learned how to use Django sessions and built a custom context processor. You also learned how to launch asynchronous tasks using Celery and RabbitMQ.

In this chapter, you will learn how to integrate a payment gateway into your site to let users pay by credit card. You will also extend the administration site with different features.

In this chapter, you will:

• Integrate the Stripe payment gateway into your project
• Process credit card payments with Stripe
• Handle payment notifications
• Export orders to CSV files
• Create custom views for the administration site
• Generate PDF invoices dynamically

The source code for this chapter can be found at https://github.com/PacktPublishing/Django-4-by-example/tree/main/Chapter09.

All Python packages used in this chapter are included in the requirements.txt...

Integrating a payment gateway

A payment gateway is a technology used by merchants to process payments from customers online. Using a payment gateway, you can manage customers’ orders and delegate payment processing to a reliable, secure third party. By using a trusted payment gateway, you won’t have to worry about the technical, security, and regulatory complexity of processing credit cards in your own system.

There are several payment gateway providers to choose from. We are going to integrate Stripe, which is a very popular payment gateway used by online services such as Shopify, Uber, Twitch, and GitHub, among others.

Stripe provides an Application Programming Interface (API) that allows you to process online payments with multiple payment methods, such as credit card, Google Pay, and Apple Pay. You can learn more about Stripe at https://www.stripe.com/.

Stripe provides different products related to payment processing. It can manage one-off payments, recurring...

Exporting orders to CSV files

Sometimes, you might want to export the information contained in a model to a file so that you can import it into another system. One of the most widely used formats to export/import data is Comma-Separated Values (CSV). A CSV file is a plain text file consisting of a number of records. There is usually one record per line and some delimiter character, usually a literal comma, separating the record fields. We are going to customize the administration site to be able to export orders to CSV files.

Adding custom actions to the administration site

Django offers a wide range of options to customize the administration site. You are going to modify the object list view to include a custom administration action. You can implement custom administration actions to allow staff users to apply actions to multiple elements at once in the change list view.

An administration action works as follows: a user selects objects from the administration object list...

Extending the administration site with custom views

Sometimes, you may want to customize the administration site beyond what is possible through configuring ModelAdmin, creating administration actions, and overriding administration templates. You might want to implement additional functionalities that are not available in existing administration views or templates. If this is the case, you need to create a custom administration view. With a custom view, you can build any functionality you want; you just have to make sure that only staff users can access your view and that you maintain the administration look and feel by making your template extend an administration template.

Let’s create a custom view to display information about an order. Edit the views.py file of the orders application and add the following code highlighted in bold:

from django.urls import reverse
from django.shortcuts import render, redirect, get_object_or_404
from django.contrib.admin.views.decorators...

Generating PDF invoices dynamically

Now that you have a complete checkout and payment system, you can generate a PDF invoice for each order. There are several Python libraries to generate PDF files. One popular library to generate PDFs with Python code is ReportLab. You can find information about how to output PDF files with ReportLab at https://docs.djangoproject.com/en/4.1/howto/outputting-pdf/.

In most cases, you will have to add custom styles and formatting to your PDF files. You will find it more convenient to render an HTML template and convert it into a PDF file, keeping Python away from the presentation layer. You are going to follow this approach and use a module to generate PDF files with Django. You will use WeasyPrint, which is a Python library that can generate PDF files from HTML templates.

Installing WeasyPrint

First, install WeasyPrint’s dependencies for your operating system from https://doc.courtbouillon.org/weasyprint/stable/first_steps.html....

Additional resources

The following resources provide additional information related to the topics covered in this chapter:

• Source code for this chapter – https://github.com/PacktPublishing/Django-4-by-example/tree/main/Chapter09
• Stripe website – https://www.stripe.com/
• Stripe Checkout documentation – https://stripe.com/docs/payments/checkout
• Creating a Stripe account – https://dashboard.stripe.com/register
• Stripe account settings – https://dashboard.stripe.com/settings/account
• Stripe Python library – https://github.com/stripe/stripe-python
• Stripe test API keys – https://dashboard.stripe.com/test/apikeys
• Stripe API keys documentation – https://stripe.com/docs/keys
• Stripe API version 2022-08-01 release notes – https://stripe.com/docs/upgrades#2022-08-01
• Stripe checkout session modes – https://stripe.com/docs/api/checkout/sessions/object#checkout_session_object...

Summary

In this chapter, you integrated the Stripe payment gateway into your project and created a webhook endpoint to receive payment notifications. You built a custom administration action to export orders to CSV. You also customized the Django administration site using custom views and templates. Finally, you learned how to generate PDF files with WeasyPrint and how to attach them to emails.

The next chapter will teach you how to create a coupon system using Django sessions and you will build a product recommendation engine with Redis.