如何在自定义PHP代码中调用WordPress函数及对接wp-invoice API

Hey there! Since your custom PHP app is hosted independently from the WordPress site running wp-invoice, you won't be able to directly include WordPress core files (like wp-load.php) to call its functions. Instead, the right approach is to use wp-invoice's REST API to fetch invoice data remotely. Here's a step-by-step breakdown tailored to your use case:

1. Confirm wp-invoice's REST API Support #

First, verify that the wp-invoice plugin exposes a REST API (most modern WordPress plugins do this out of the box). Check the plugin's documentation to find the exact API endpoints you'll need—common ones include:

• Fetching a user's invoices (e.g., /wp-json/wp-invoice/v1/invoices)
• Fetching a single invoice by ID (e.g., /wp-json/wp-invoice/v1/invoices/{id})

2. Set Up Cross-Server Authentication #

To access user-specific invoices, you need to authenticate your PHP app's requests to the WordPress API. Two reliable methods for cross-server setups are:

Option A: JWT Authentication #

• Install a JWT authentication plugin on your WordPress site to enable token-based auth.
• When a user logs into your PHP app, send their credentials (email/password) to WordPress's JWT login endpoint (e.g., /wp-json/jwt-auth/v1/token). You'll get a JSON Web Token (JWT) in response.
• Include this token in the Authorization header of all subsequent wp-invoice API requests.

Option B: API Key Authentication #

• If wp-invoice supports API keys (check its docs), generate a unique API key in your WordPress admin panel.
• Include this key in your API requests—either as a query parameter (e.g., ?api_key=your-key-here) or a custom request header (e.g., X-API-Key: your-key-here).

3. Fetch Invoices in Your PHP Code #

Use cURL (the most flexible option) to send authenticated requests to the wp-invoice API. Here's a working example:

// Replace these with your actual values
$wordpress_base_url = 'https://your-wordpress-site.com';
$jwt_token = 'your-valid-jwt-token'; // From JWT auth step
$user_id = 123; // Match the user's ID in your WordPress site

// Build the API endpoint for fetching the user's invoices
$invoice_api_url = $wordpress_base_url . '/wp-json/wp-invoice/v1/invoices?user_id=' . $user_id;

// Initialize cURL request
$ch = curl_init($invoice_api_url);

// Set request headers with authentication
curl_setopt($ch, CURLOPT_HTTPHEADER, [
    'Authorization: Bearer ' . $jwt_token,
    'Content-Type: application/json'
]);

// Return response as string instead of printing it
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

// Execute the request
$response = curl_exec($ch);
$http_status = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);

// Handle the response
if ($http_status === 200 && $response) {
    $invoices = json_decode($response, true);
    
    // Render invoices to your user (customize this to match your app's UI)
    echo '<h2>Your Invoices</h2>';
    foreach ($invoices as $invoice) {
        echo '<div class="invoice-card">';
        echo '<p><strong>Invoice #:</strong> ' . htmlspecialchars($invoice['number']) . '</p>';
        echo '<p><strong>Date:</strong> ' . htmlspecialchars($invoice['date_created']) . '</p>';
        echo '<p><strong>Total:</strong> ' . htmlspecialchars($invoice['total']) . '</p>';
        echo '</div>';
    }
} else {
    // Handle errors (e.g., invalid token, no invoices found)
    switch ($http_status) {
        case 401:
            echo 'Error: Unauthorized access. Please check your authentication token.';
            break;
        case 404:
            echo 'Error: Invoice API endpoint not found.';
            break;
        default:
            echo 'Failed to load invoices. Please try again later.';
    }
}

4. Key Considerations for Security & Reliability #

• Don't hardcode credentials: Store JWT tokens, API keys, and WordPress URLs in a secure config file or environment variables (never in your public code).
• Validate user identity: Ensure the user logged into your PHP app matches the user whose invoices you're fetching (use unique identifiers like email or linked user IDs).
• Handle CORS if needed: If your app is served from a different domain than WordPress, you may need to enable CORS on the WordPress site (via a plugin or custom .htaccess rules).
• Error handling: Always check HTTP status codes and handle failures gracefully for a better user experience.

内容的提问来源于stack exchange，提问作者ielaajez