Lesson 70: Building the Payment Page Foundation for Completed Auctions
Introduction
After successfully completing the auction lifecycle in the previous lessons, the next logical step is to allow auction winners to complete their purchase.
By the end of Lesson 69, Flipnzee Auctions was already capable of:
- Creating and managing auctions
- Automatically closing expired auctions
- Determining the winning bidder
- Recording transactions
- Displaying transactions in the WordPress admin
- Showing buyers their purchases
- Displaying purchase details
- Providing a Pay Now button for unpaid purchases
Although the Pay Now button existed, clicking it resulted in a 404 Page Not Found error because the payment page itself had not yet been implemented.
Lesson 70 focuses on solving this problem by creating the foundation of the payment workflow.
Why This Lesson Is Important
Every online marketplace requires a secure payment flow after an auction ends.
Instead of jumping directly into integrating a payment gateway like Stripe or PayPal, it is better to build the underlying architecture first.
This lesson concentrates on creating the page that receives the transaction, validates it, and displays the purchase before any actual payment processing takes place.
Building the foundation first makes later gateway integration much cleaner and easier.
Objectives
In this lesson we will:
- Create the Payment Page shortcode
- Build a dedicated Payment Page class
- Register the shortcode with the plugin loader
- Display transaction information
- Validate transaction IDs
- Handle missing or invalid transactions gracefully
- Prepare the page for future payment gateway integration
Planned Workflow
To keep development safe and manageable, this lesson will be completed in several small checkpoints.
Checkpoint 1
Create the Payment Page class.
Checkpoint 2
Register the payment shortcode.
Checkpoint 3
Display transaction information.
Checkpoint 4
Handle invalid transactions.
Checkpoint 5
Test the page using existing auction transactions.
Checkpoint 6
Commit the completed lesson to Git.
Expected User Flow
Auction Ends
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Winner Determined
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Transaction Created
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Buyer Visits "My Purchases"
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Clicks "Pay Now"
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Payment Page Opens
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Transaction Validated
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Ready for Payment Gateway
Development Strategy
One important improvement in our workflow is the use of small Git checkpoints.
At the beginning of this lesson, the entire project was restored to the stable Lesson 69 state and committed to GitHub. This provides a reliable rollback point before introducing the payment workflow.
Rather than implementing the complete payment system in one attempt, each stage will be developed, tested, and committed separately. This incremental approach reduces risk, simplifies debugging, and ensures that any issues can be isolated without affecting previously completed features.
What We’ll Build Next
By the end of Lesson 70, clicking the Pay Now button should no longer produce a 404 error. Instead, buyers will be taken to a dedicated payment page displaying the transaction details, confirming the amount due, and preparing the auction purchase for payment processing in the upcoming lessons.
Next Lesson: Implementing the Payment Page and Connecting the “Pay Now” Workflow.