feat: Add Mailchimp Campaign Archive block and shortcode (#811)

[faisalahammad]

Summary

Adds a new shortcode [mc4wp_campaigns] and a native Gutenberg block to display an archive of sent Mailchimp campaigns directly on a WordPress site.

Fixes #811

Problem

Users currently lack an official, built-in way to display their Mailchimp campaign history on their sites without relying on third-party plugins or manual embeds.

Solution

Implemented a WordPress shortcode and a Gutenberg block that fetch and render the user's sent campaigns. We use the existing MC4WP_API_V3 wrapper and transient caching to ensure performance and prevent rate-limiting.

Changes

includes/campaigns/class-archive.php

Before:

// File didn't exist

After:

public function shortcode($attributes = []) {
    // ...
    $campaigns = $this->get_campaigns($count);
    if (empty($campaigns) || ! is_array($campaigns)) {
        return is_string($campaigns) ? $campaigns : '';
    }
    // ...
}

Why: Centralized logic for both the shortcode and server-side block rendering. It correctly extracts the campaigns array from the API response object and leverages transient caching.

assets/src/js/campaigns-block.js

Before:

// File didn't exist

After:

edit: function ({ attributes, setAttributes }) {
    return (
      <div>
        <InspectorControls>
          // ...
        </InspectorControls>
        // ...
      </div>
    )
}

Why: Registers editor UI that aligns with mailchimp-for-wp standards. It is explicitly wrapped in standard <div> instead of React Fragment <> syntax to guarantee @babel/preset-env compatibility during compilation.

Testing

Test 1: Shortcode Rendering
Steps:

1. Added [mc4wp_campaigns]
2. Verified shortcode maps settings correctly
3. Cached on load

Result: Works as expected

Test 2: Transient Caching & API Errors
Steps:

1. Disconnected API
2. View frontend
3. Handled gracefully with HTML debug comment for admins only

Result: Handled correctly

Automated:

$ composer run-script test
OK (62 tests, 190 assertions)

$ vendor/bin/phpcs -n -s
Exit code: 0

Build

mailchimp-for-wp-feature-811.zip available for manual testing
Install: WP Admin → Plugins → Upload

Screenshot