In the previous lesson, the Flipnzee Auctions plugin stopped displaying auctions immediately after they were closed. While that prevented further bidding, it also removed the auction from public view, making it impossible for visitors to see the final auction result.

In this lesson, the plugin was improved so that closed auctions remain visible. Instead of disappearing, they now display an “Auction Ended” status and prevent any further bids from being placed.

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Why This Change Was Needed

Previously, once an auction status became closed, the frontend shortcode only retrieved active auctions.

This caused several problems:

• Visitors could no longer view completed auctions.
• Final bid information disappeared.
• Buyers could not see that an auction had successfully concluded.
• There was no indication that bidding had ended.

A completed auction is still valuable information, so it should remain publicly visible.

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Step 1: Update the Auction Query

Open:

includes/class-auction-manager.php

Locate the method:

public static function get_active_auctions()

Replace the query with:

public static function get_active_auctions() {

	global $wpdb;

	$table = $wpdb->prefix . 'flipnzee_auctions';

	return $wpdb->get_results(
		"SELECT *
		FROM {$table}
		WHERE status IN ('active', 'closed')
		ORDER BY auction_end ASC",
		ARRAY_A
	);
}

Instead of returning only active auctions, the method now also retrieves closed auctions.

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Step 2: Detect Whether an Auction Has Ended

Inside:

includes/class-shortcodes.php

After loading the auction information, determine its current state:

$current_time = current_time( 'timestamp' );
$end_time     = strtotime( $auction['auction_end'] );

if ( $end_time <= $current_time ) {

	$status       = 'ended';
	$status_label = '🔴 Auction Ended';

} elseif ( ( $end_time - $current_time ) <= DAY_IN_SECONDS ) {

	$status       = 'ending';
	$status_label = '🟡 Ending Soon';

} else {

	$status       = 'live';
	$status_label = '🟢 Live Auction';

}

This allows the auction card to dynamically display whether the auction is live, ending soon, or has already ended.

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Step 3: Display the Auction Status Badge

Above the auction title, output the status label:

<div class="flipnzee-auction-status <?php echo esc_attr( $status ); ?>">
	<?php echo esc_html( $status_label ); ?>
</div>

Visitors can now instantly recognise the auction state.

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Step 4: Prevent Further Bidding

Hide the bidding form after the auction has ended.

Example:

<?php if ( $status !== 'ended' ) : ?>

	<!-- Bid form -->

<?php else : ?>

	<div class="flipnzee-auction-closed">
		<strong>🏁 Auction Closed</strong><br>
		This auction has ended. No further bids are accepted.
	</div>

<?php endif; ?>

This ensures the auction remains visible while preventing additional bids.

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Step 5: Style the Closed Auction Notice

In:

assets/css/frontend.css

Add:

.flipnzee-auction-closed {
	background: #fff5f5;
	border: 1px solid #e74c3c;
	color: #b71c1c;
	padding: 12px;
	margin-top: 15px;
	border-radius: 6px;
	font-size: 14px;
}

The notice clearly communicates that bidding has finished.

---

Testing

The implementation was tested by viewing a closed auction.

Expected behaviour:

• The auction card remained visible.
• The status badge changed to Auction Ended.
• The bid form disappeared.
• Visitors were informed that no further bids would be accepted.

During testing, it was also observed that historical test auctions remained visible because multiple auction records had been created for the same listing during development. This highlighted an architectural improvement that would be addressed in the next lesson.

Download Source Code

Download the completed version after this lesson:

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What Was Learned

This lesson improved the user experience by ensuring that completed auctions remain publicly visible instead of disappearing. Visitors can continue viewing the listing, the auction status, and historical information, while the system correctly prevents any new bids after the auction has ended.

The implementation also revealed the importance of maintaining a single auction record per listing, which would become the focus of the next lesson to simplify auction management and avoid duplicate auction histories.

In the previous lesson, the Flipnzee Auctions plugin redirected users back to the auction page after a bid was processed. While the functionality worked, users had no confirmation that their bid had been accepted or rejected.

In this implementation lesson, the plugin is enhanced to display clear success and error notifications using URL parameters, providing a much better user experience.

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Objective

Implement professional notification messages that inform users whether:

• Their bid was accepted.
• Their bid was rejected.

Instead of silently refreshing the page, users now receive immediate feedback.

---

Step 1: Redirect With Status Parameter

The bid handler already redirects back to the auction page.

Instead of simply redirecting:

wp_safe_redirect( get_permalink( $listing_id ) );
exit;

it was updated to include a status parameter.

Successful bid:

wp_safe_redirect(
    add_query_arg(
        'bid',
        'success',
        get_permalink( $listing_id )
    )
);

exit;

Failed bid:

wp_safe_redirect(
    add_query_arg(
        'bid',
        'failed',
        get_permalink( $listing_id )
    )
);

exit;

This produces URLs like:

https://flipnzee.com/testing/?bid=success

or

https://flipnzee.com/testing/?bid=failed

---

Step 2: Detect the Status Parameter

Inside includes/class-shortcodes.php, just before displaying the auction details table, a check was added.

<?php

if ( isset( $_GET['bid'] ) ) {

    $status = sanitize_text_field(
        wp_unslash( $_GET['bid'] )
    );

    if ( 'success' === $status ) {
        ?>

        <div class="flipnzee-notice flipnzee-success">
            ✅ Your bid has been placed successfully.
        </div>

        <?php

    } elseif ( 'failed' === $status ) {
        ?>

        <div class="flipnzee-notice flipnzee-error">
            ❌ Your bid could not be accepted.
        </div>

        <?php
    }
}
?>

The plugin now safely reads the URL parameter and displays the appropriate message.

---

Step 3: Style the Notifications

The following CSS was added to assets/css/frontend.css.

.flipnzee-notice {

    padding: 15px;

    margin: 20px 0;

    border-radius: 6px;

    font-weight: 600;

}

.flipnzee-success {

    background: #ecfdf3;

    color: #046c4e;

    border-left: 5px solid #10b981;

}

.flipnzee-error {

    background: #fef2f2;

    color: #b91c1c;

    border-left: 5px solid #ef4444;

}

These styles make notifications stand out while remaining consistent with modern WordPress admin and frontend design.

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Step 4: Test the Feature

Two scenarios were tested.

Successful Bid

After placing a valid bid, the user is redirected to:

?bid=success

and sees:

✅ Your bid has been placed successfully.

Failed Bid

If the bid is rejected, the user is redirected to:

?bid=failed

and sees:

❌ Your bid could not be accepted.

---

Troubleshooting During Implementation

Several issues were encountered before the feature worked correctly.

1. Notification Did Not Appear

Initially, the URL contained:

?bid=success

but no message appeared.

The issue was that the notification block had been inserted inside a section of code that wasn’t executed at the correct point in the page lifecycle.

Moving the notification logic immediately before the auction details table resolved the problem.

---

2. PHP Syntax Error

A parse error occurred after moving code.

Using the PHP linter helped identify the exact line causing the issue.

php -l includes/class-shortcodes.php

This quickly revealed an unexpected token error, allowing it to be corrected before uploading the plugin.

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3. HTML Structure

During implementation, the winning/outbid status message was accidentally placed inside a <tr> element.

This produced invalid HTML.

The message block was moved outside the table so that the auction metadata table remained structurally correct.

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4. User Display Name

While testing, the highest bidder appeared simply as:

user

instead of the expected display name.

The SQL query was working correctly—the WordPress account’s Display Name was simply set to “user”. Updating the profile’s display name fixed the issue.

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Final Result

The auction page now provides immediate visual feedback whenever a bid is processed.

Users no longer have to guess whether their action succeeded, making the bidding experience more intuitive and professional.

Download Source Code

Download the starting version of the plugin before the lesson:

Download the completed version after this lesson:

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What We Learned

In this lesson, we learned how to:

• Redirect users with URL parameters.
• Read query string values safely using sanitize_text_field() and wp_unslash().
• Display contextual success and error notices.
• Style frontend notifications with CSS.
• Validate PHP files using the built-in linter.
• Keep HTML structure valid while inserting dynamic content.

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Conclusion

Although the underlying bidding logic was already functional, adding user-facing notifications significantly improved the usability of the Flipnzee Auctions plugin. Small enhancements like clear feedback messages create a smoother and more professional user experience, reducing confusion and increasing user confidence during the bidding process.

In the previous lesson, we discussed why an auction system should not allow the current highest bidder to keep increasing their own bid. In this implementation lesson, we’ll add server-side validation that prevents self-bidding.

By the end of this lesson, if the highest bidder attempts to place another bid, the bid will be rejected before it is saved to the database.

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Step 1: Open the Bid Manager

Open the following file:

includes/class-bid-manager.php

Locate the place_bid() method:

public static function place_bid(
    $auction_id,
    $bidder_id,
    $bid_amount
) {

---

Step 2: Retrieve the Current Highest Bidder

Inside the function, locate the following code:

global $wpdb;

$bid_table = $wpdb->prefix . 'flipnzee_bids';

$auction_table = $wpdb->prefix . 'flipnzee_auctions';

Immediately after it, add:

$highest_bidder = self::get_highest_bidder(
    $auction_id
);

The beginning of the function now becomes:

global $wpdb;

$bid_table = $wpdb->prefix . 'flipnzee_bids';

$auction_table = $wpdb->prefix . 'flipnzee_auctions';

$highest_bidder = self::get_highest_bidder(
    $auction_id
);

This loads the user who currently owns the highest bid.

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Step 3: Locate the Current Bid

Further down in the same function, locate the code that retrieves the current bid:

$current_bid = $wpdb->get_var(
    $wpdb->prepare(
        "SELECT current_bid
        FROM {$auction_table}
        WHERE id = %d",
        $auction_id
    )
);

---

Step 4: Prevent Self-Bidding

Immediately after the code above, add:

if (
    $highest_bidder &&
    (int) $highest_bidder->bidder_id === (int) $bidder_id
) {

    return new WP_Error(

        'already_highest_bidder',

        __(
            'You are already the highest bidder.',
            'flipnzee-auctions'
        )

    );

}

The complete section now becomes:

$current_bid = $wpdb->get_var(
    $wpdb->prepare(
        "SELECT current_bid
        FROM {$auction_table}
        WHERE id = %d",
        $auction_id
    )
);

if (
    $highest_bidder &&
    (int) $highest_bidder->bidder_id === (int) $bidder_id
) {

    return new WP_Error(

        'already_highest_bidder',

        __(
            'You are already the highest bidder.',
            'flipnzee-auctions'
        )

    );

}

Whenever the logged-in user is already leading the auction, the function stops immediately and returns a WP_Error.

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Step 5: Upload the Updated Plugin

Create a fresh ZIP archive of the plugin:

zip -r flipnzee-auctions.zip flipnzee-auctions

Upload it through:

Plugins → Add New → Upload Plugin

Activate the updated version.

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Step 6: Test the Feature

Log in as the user who currently has the highest bid.

Try placing another bid.

Expected Result

The bid is rejected.

No new row is inserted into the bids table.

The current bid remains unchanged.

Although no message is displayed yet, the backend validation is working correctly.

---

Complete Source Code

Retrieve the Highest Bidder

global $wpdb;

$bid_table = $wpdb->prefix . 'flipnzee_bids';

$auction_table = $wpdb->prefix . 'flipnzee_auctions';

$highest_bidder = self::get_highest_bidder(
    $auction_id
);

---

Prevent Self-Bidding

$current_bid = $wpdb->get_var(
    $wpdb->prepare(
        "SELECT current_bid
        FROM {$auction_table}
        WHERE id = %d",
        $auction_id
    )
);

if (
    $highest_bidder &&
    (int) $highest_bidder->bidder_id === (int) $bidder_id
) {

    return new WP_Error(

        'already_highest_bidder',

        __(
            'You are already the highest bidder.',
            'flipnzee-auctions'
        )

    );

}

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What We Achieved

By implementing this lesson, we made the auction system smarter and fairer.

The plugin now:

• Prevents users from bidding against themselves.
• Stops unnecessary increases in the auction price.
• Uses secure server-side validation that cannot be bypassed from the browser.
• Returns a WP_Error when a self-bid is detected.
• Ensures the current bid and bid history remain unchanged when the validation fails.

At this stage, the validation works correctly, although users do not yet receive a visible explanation when their bid is rejected.

Download Source Code

Download the starting version of the plugin before the lesson:

Download the completed version after this lesson:

What’s Next?

In Lesson 49, we’ll build a proper notification system to display friendly success and error messages after bid submission, including:

• ✅ Bid placed successfully.
• ❌ You are already the highest bidder.
• ❌ Bid amount is too low.
• ❌ Auction has ended.

This will complete the bidding workflow and provide users with clear, professional feedback after every action.