Subscription System

Last updated: January 26, 2026

Comprehensive email subscription management system allowing artists to collect and manage subscriber lists with multiple collection methods and export capabilities.

Database Schema

Subscriber Table

Location: inc/database/subscriber-db.php

CREATE TABLE wp_artist_subscribers (
    subscriber_id BIGINT(20) UNSIGNED NOT NULL AUTO_INCREMENT,
    user_id BIGINT(20) UNSIGNED NULL,
    artist_profile_id BIGINT(20) UNSIGNED NOT NULL,
    subscriber_email VARCHAR(255) NOT NULL,
    username VARCHAR(60) NULL DEFAULT NULL,
    source VARCHAR(50) NOT NULL DEFAULT 'platform_follow_consent',
    subscribed_at DATETIME NOT NULL,
    exported TINYINT(1) NOT NULL DEFAULT 0,
    PRIMARY KEY (subscriber_id),
    UNIQUE KEY email_artist (subscriber_email, artist_profile_id),
    KEY artist_profile_id (artist_profile_id),
    KEY exported (exported),
    KEY user_id (user_id),
    KEY user_artist_source (user_id, artist_profile_id, source)
);

Table Creation

function extrch_create_subscribers_table() {
    global $wpdb;
    require_once(ABSPATH . 'wp-admin/includes/upgrade.php');
    
    $table_name = $wpdb->prefix . 'artist_subscribers';
    $charset_collate = $wpdb->get_charset_collate();
    
    $sql = "CREATE TABLE $table_name (
        subscriber_id BIGINT(20) UNSIGNED NOT NULL AUTO_INCREMENT,
        user_id BIGINT(20) UNSIGNED NULL,
        artist_profile_id BIGINT(20) UNSIGNED NOT NULL,
        subscriber_email VARCHAR(255) NOT NULL,
        username VARCHAR(60) NULL DEFAULT NULL,
        source VARCHAR(50) NOT NULL DEFAULT 'platform_follow_consent',
        subscribed_at DATETIME NOT NULL,
        exported TINYINT(1) NOT NULL DEFAULT 0,
        PRIMARY KEY (subscriber_id),
        UNIQUE KEY email_artist (subscriber_email, artist_profile_id),
        KEY artist_profile_id (artist_profile_id),
        KEY exported (exported),
        KEY user_id (user_id),
        KEY user_artist_source (user_id, artist_profile_id, source)
    ) $charset_collate;";
    
    dbDelta($sql);
}

Subscription Collection Methods

Inline Form

Location: inc/link-pages/live/templates/subscribe-inline-form.php

Embedded form within link page content:

<div class="subscribe-inline-form">
    <h3><?php echo esc_html($subscribe_description); ?></h3>
    <form id="inline-subscribe-form" class="subscribe-form">
        <input type="email" 
               name="subscriber_email" 
               placeholder="Enter your email" 
               required>
        <button type="submit"><?php echo esc_html($subscribe_button_text); ?></button>
        <input type="hidden" name="artist_id" value="<?php echo esc_attr($artist_id); ?>">
        <input type="hidden" name="source" value="inline_form">
    </form>
    <div class="subscribe-message"></div>
</div>

Modal Form

Location: inc/link-pages/live/templates/subscribe-modal.php

Modal popup triggered by button or icon:

<div id="extrch-subscribe-modal" class="extrch-subscribe-modal extrch-modal extrch-modal-hidden" role="dialog" aria-modal="true" aria-labelledby="extrch-subscribe-modal-title">
    <div class="modal-content">
        <span class="close-modal">&times;</span>
        <h3>Subscribe to <?php echo esc_html($artist_name); ?></h3>
        <p><?php echo esc_html($subscribe_description); ?></p>
        
        <form id="modal-subscribe-form" class="subscribe-form">
            <input type="email" 
                   name="subscriber_email" 
                   placeholder="Enter your email" 
                   required>
            <button type="submit"><?php echo esc_html($subscribe_button_text); ?></button>
            <input type="hidden" name="artist_id" value="<?php echo esc_attr($artist_id); ?>">
            <input type="hidden" name="source" value="modal_form">
        </form>
        
        <div class="subscribe-message"></div>
    </div>
</div>

Icon Trigger

Subscription icon that opens modal:

<?php if ($subscribe_display_mode === 'icon_modal'): ?>
    <button type="button" class="extrch-subscribe-trigger">
        <i class="fas fa-envelope"></i>
        <span>Subscribe</span>
    </a>
<?php endif; ?>

JavaScript Integration

Client-Side Handling

Location: inc/link-pages/live/assets/js/link-page-subscribe.js

const SubscriptionManager = {
    init: function() {
        this.bindEvents();
    },

    bindEvents: function() {
        // Modal triggers
        document.addEventListener('click', (e) => {
            if (e.target.matches('.subscribe-trigger-icon')) {
                this.openModal(e);
            } else if (e.target.matches('.close-modal')) {
                this.closeModal(e);
            }
        });

        // Form submissions
        document.addEventListener('submit', (e) => {
            if (e.target.matches('.subscribe-form')) {
                this.handleSubscription(e);
            }
        });
    },

    openModal: function(e) {
        e.preventDefault();
        const modal = document.getElementById('subscribe-modal');
        if (modal) modal.style.display = 'block';
    },

    closeModal: function(e) {
        e.preventDefault();
        const modal = document.getElementById('subscribe-modal');
        if (modal) modal.style.display = 'none';
    },

    handleSubscription: function(e) {
        e.preventDefault();

        const form = e.target;
        const email = form.querySelector('input[name="subscriber_email"]').value;
        const artistId = form.querySelector('input[name="artist_id"]').value;
        const source = form.querySelector('input[name="source"]').value;

        fetch('/wp-json/extrachill/v1/subscribe', {
            method: 'POST',
            headers: {
                'Content-Type': 'application/json',
                'X-WP-Nonce': document.querySelector('[data-nonce-field]').value
            },
            body: JSON.stringify({
                subscriber_email: email,
                artist_id: artistId,
                source: source
            })
        })
        .then(response => response.json())
        .then(data => {
            if (data.success) {
                form.style.display = 'none';
                const messageEl = document.querySelector('.subscribe-message');
                if (messageEl) {
                    messageEl.innerHTML = '<p class="success">' + data.message + '</p>';
                }

                // Close modal after delay if modal form
                if (source === 'modal_form') {
                    setTimeout(() => {
                        const modal = document.getElementById('subscribe-modal');
                        if (modal) modal.style.display = 'none';
                    }, 2000);
                }
            } else {
                const messageEl = document.querySelector('.subscribe-message');
                if (messageEl) {
                    messageEl.innerHTML = '<p class="error">' + data.message + '</p>';
                }
            }
        });
    }
};

document.addEventListener('DOMContentLoaded', () => SubscriptionManager.init());

Server-Side Processing

Data Functions

Location: inc/artist-profiles/subscribe-data-functions.php

/**
 * Add subscriber to database
 */
function add_artist_subscriber($email, $artist_id, $source = 'platform_follow_consent') {
    global $wpdb;
    
    $table_name = $wpdb->prefix . 'artist_subscribers';
    
    // Check for existing subscription
    $existing = $wpdb->get_var($wpdb->prepare("
        SELECT subscriber_id FROM {$table_name} 
        WHERE subscriber_email = %s AND artist_profile_id = %d
    ", $email, $artist_id));
    
    if ($existing) {
        return ['success' => false, 'message' => 'You are already subscribed'];
    }
    
    // Get user ID if registered user
    $user = get_user_by('email', $email);
    $user_id = $user ? $user->ID : null;
    $username = $user ? $user->display_name : null;
    
    // Insert subscriber
    $result = $wpdb->insert(
        $table_name,
        [
            'user_id' => $user_id,
            'artist_profile_id' => $artist_id,
            'subscriber_email' => $email,
            'username' => $username,
            'source' => $source,
            'subscribed_at' => current_time('mysql'),
            'exported' => 0
        ],
        ['%d', '%d', '%s', '%s', '%s', '%s', '%d']
    );
    
    if ($result === false) {
        return ['success' => false, 'message' => 'Failed to save subscription'];
    }
    
    // Trigger action for integrations
    do_action('extrch_subscriber_added', $wpdb->insert_id, $email, $artist_id, $source);
    
    return ['success' => true, 'message' => 'Subscription added successfully'];
}

/**
 * Get subscribers for artist
 */
function get_artist_subscribers($artist_id, $args = []) {
    global $wpdb;
    
    $defaults = [
        'per_page' => 20,
        'page' => 1,
        'include_exported' => false,
        'source' => null
    ];
    $args = wp_parse_args($args, $defaults);
    
    $table_name = $wpdb->prefix . 'artist_subscribers';
    $offset = ($args['page'] - 1) * $args['per_page'];
    
    $where_clause = $wpdb->prepare("WHERE artist_profile_id = %d", $artist_id);
    
    if (!$args['include_exported']) {
        $where_clause .= " AND (exported = 0 OR exported IS NULL)";
    }
    
    if ($args['source']) {
        $where_clause .= $wpdb->prepare(" AND source = %s", $args['source']);
    }
    
    $sql = $wpdb->prepare("
        SELECT * FROM {$table_name} 
        {$where_clause} 
        ORDER BY subscribed_at DESC 
        LIMIT %d OFFSET %d
    ", $args['per_page'], $offset);
    
    return $wpdb->get_results($sql);
}

Management Interface

Subscriber Management Tab

Location: inc/artist-profiles/frontend/templates/manage-artist-profile-tabs/tab-subscribers.php

Features:

  • Subscriber list with pagination
  • Export functionality
  • Bulk actions
  • Source filtering

JavaScript Management

Location: inc/artist-profiles/assets/js/manage-artist-subscribers.js

Subscriber management uses REST API with fetch API for modern data handling:

// Fetch subscribers via REST API
const response = await fetch( `/wp-json/extrachill/v1/subscribers/${artistId}`, {
    method: 'GET',
    credentials: 'same-origin',
    headers: {
        'X-WP-Nonce': wpApiNonce
    }
});

const subscribers = await response.json();

Export Functionality

CSV Export

/**
 * Export subscribers to CSV
 */
function export_artist_subscribers_csv() {
    if (!wp_verify_nonce($_GET['nonce'], 'subscriber_export_nonce')) {
        wp_die('Security check failed');
    }
    
    $artist_id = (int) $_GET['artist_id'];
    
    // Check permissions
    if (!ec_can_manage_artist(get_current_user_id(), $artist_id)) {
        wp_die('Insufficient permissions');
    }
    
    // Get all subscribers
    $subscribers = get_artist_subscribers($artist_id, ['per_page' => -1]);
    
    // Set CSV headers
    header('Content-Type: text/csv');
    header('Content-Disposition: attachment; filename="subscribers-' . $artist_id . '-' . date('Y-m-d') . '.csv"');
    
    $output = fopen('php://output', 'w');
    
    // Write header row
    fputcsv($output, ['Email', 'Username', 'Source', 'Subscribed Date', 'User ID']);
    
    // Write data rows
    foreach ($subscribers as $subscriber) {
        fputcsv($output, [
            $subscriber->subscriber_email,
            $subscriber->username ?: 'N/A',
            $subscriber->source,
            $subscriber->subscribed_at,
            $subscriber->user_id ?: 'N/A'
        ]);
    }
    
    fclose($output);
    
    // Mark as exported
    mark_subscribers_as_exported($artist_id);
    
    exit;
}

/**
 * Mark subscribers as exported
 */
function mark_subscribers_as_exported($artist_id) {
    global $wpdb;
    
    $table_name = $wpdb->prefix . 'artist_subscribers';
    
    $wpdb->update(
        $table_name,
        ['exported' => 1],
        ['artist_profile_id' => $artist_id, 'exported' => 0],
        ['%d'],
        ['%d', '%d']
    );
}

Subscription Sources

Source Types

The system tracks subscription sources:

  • inline_form: Inline form on link page
  • modal_form: Modal popup form
  • icon_modal: Icon-triggered modal
  • platform_follow_consent: Following artist on platform
  • manual_import: Manually imported subscribers

Source-Based Filtering

// Get subscribers by source
$modal_subscribers = extrch_get_artist_subscribers( $artist_id, array( 'source' => 'modal_form' ) );
$inline_subscribers = extrch_get_artist_subscribers( $artist_id, array( 'source' => 'inline_form' ) );

Integration Points

Email Service Integration

This plugin stores subscribers and exposes them via the REST API (extrachill/v1/artists/{artistId}/subscribers). It does not ship built-in integrations for external email providers.

If another plugin wants to sync subscribers to an ESP, implement that in the integrating plugin by calling the subscriber creation helpers from this plugin (see inc/database/subscriber-db.php) and/or listening to events in the consuming layer (the Extra Chill Platform typically centralizes these kinds of integrations in other plugins).

WordPress User Integration

Subscriber rows optionally store a user_id when the subscription is associated with a logged-in WordPress account.

The artist platform does not implement an in-plugin "follow" UI or follow-to-subscribe automation. Integrations that want to subscribe users programmatically should call add_artist_subscriber() directly.

Privacy Compliance

Data Protection

/**
 * Remove subscriber data (GDPR compliance)
 */
function remove_subscriber_data($email, $artist_id = null) {
    global $wpdb;
    
    $table_name = $wpdb->prefix . 'artist_subscribers';
    
    $where = ['subscriber_email' => $email];
    $where_format = ['%s'];
    
    if ($artist_id) {
        $where['artist_profile_id'] = $artist_id;
        $where_format[] = '%d';
    }
    
    $result = $wpdb->delete($table_name, $where, $where_format);
    
    do_action('extrch_subscriber_data_removed', $email, $artist_id);
    
    return $result;
}

Unsubscribe Functionality

/**
 * Generate unsubscribe link
 */
function generate_unsubscribe_link($email, $artist_id) {
    $token = wp_hash($email . $artist_id . wp_salt());
    
    return add_query_arg([
        'action' => 'unsubscribe',
        'email' => urlencode($email),
        'artist' => $artist_id,
        'token' => $token
    ], home_url());
}

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