After planning the architecture in Lesson 80, it was time to implement one of the most important structural improvements in the Flipnzee Auctions plugin.

Earlier versions of the plugin prevented duplicate auctions by updating the existing auction whenever the same listing was selected. While this solved duplicate auction creation, it also prevented maintaining a complete auction history.

This lesson redesigns the logic so that a listing can have unlimited historical auctions while ensuring that only one auction can remain active at any given time.

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The Problem

Originally, the plugin searched for any auction belonging to the listing.

$existing_auction = $wpdb->get_var(
    $wpdb->prepare(
        "SELECT id
        FROM {$table}
        WHERE listing_id = %d
        LIMIT 1",
        $listing_id
    )
);

If one existed, it was updated instead of creating a new auction.

Although simple, this approach caused a major limitation:

• historical auctions could never be preserved
• every new auction overwrote the previous one
• reporting and analytics became inaccurate

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New Design

Instead of checking whether the listing has ever been auctioned, the plugin now checks only for active auctions.

Conceptually the lookup becomes:

SELECT id
FROM wp_flipnzee_auctions
WHERE listing_id = ?
AND status = 'active'
LIMIT 1;

This small change completely changes the behaviour of the system.

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Behaviour Before

Listing 494

Auction ID	Status
15	Closed

Creating another auction resulted in:

Auction #15 being updated.

No historical record remained.

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Behaviour After

Listing 494

Auction ID	Status
15	Closed
21	Closed
27	Closed
35	Active

Each completed auction remains permanently stored.

Only one auction is active.

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Code Changes

The auction lookup logic was modified so only active auctions are considered duplicates.

If an active auction exists:

• update that active auction
• return its ID

Otherwise:

• insert a completely new auction record

This preserves auction history while still preventing multiple active auctions for the same listing.

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Testing Performed

Several scenarios were tested.

Test 1

Create first auction

Result:

• New auction created

✔ Passed

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Test 2

Create another auction while first auction is active

Result:

• Existing active auction updated

✔ Passed

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Test 3

Close auction

Result:

Auction status became Closed.

✔ Passed

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Test 4

Create a new auction for the same listing

Result:

A brand-new auction record was inserted.

Previous closed auction remained untouched.

✔ Passed

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Test 5

Verify All Auctions page

The administration screen correctly displayed:

Auction #35   Active
Auction #34   Closed

Both auctions belong to the same listing.

History is preserved.

✔ Passed

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Benefits

The redesigned architecture provides several advantages:

• Unlimited auction history
• One active auction per listing
• Cleaner reporting
• Better analytics
• Easier auditing
• Marketplace-style auction lifecycle
• Future support for auction history pages

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What Was Learned

A small SQL condition can dramatically change application behaviour.

Instead of asking:

“Has this listing ever had an auction?”

the system now asks:

“Does this listing currently have an active auction?”

This subtle change aligns the plugin with how professional marketplace platforms typically manage auction lifecycles.

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Source Code

The implementation focused primarily on:

• includes/class-auction-manager.php

Key improvements included:

• checking only for active auctions
• preserving closed auctions
• creating new records only when no active auction exists
• maintaining a single active auction per listing

Download Source Code

Download the starting version of the plugin before the lesson:

Download the completed version after this lesson:

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Final Result

Lesson 80 successfully redesigned the auction creation workflow.

The Flipnzee Auctions plugin now supports unlimited historical auctions while enforcing a single active auction per listing, providing a scalable foundation for future features such as auction archives, historical analytics, relisting workflows, and seller performance tracking.

• Category: Build Along