Solving WordPress REST API Content Stripping Issues

Why Your WordPress REST API Posts Lose Content

As a developer, you've likely encountered the frustration of using the WordPress REST API to create custom posts, only to find that part of your content has mysteriously disappeared. This issue can be particularly annoying when you're confident the input is correct, but WordPress doesn't render it as expected.

This specific challenge often arises when using advanced blocks or plugins like Kadence. In many cases, WordPress applies internal filters or sanitization processes that strip out unsupported or improperly formatted content. The problem becomes even trickier when dynamic blocks or custom settings are involved.

Imagine spending hours perfecting a layout with background images, unique IDs, and responsive settings, only to see those carefully designed details vanish into thin air. It's a common scenario for developers relying on plugins like Kadence to deliver rich layouts via the REST API.

But don’t worry, this isn’t an unsolvable mystery. By understanding how WordPress handles content sanitization and applying a few best practices, you can ensure your API calls deliver the desired results without any unwelcome surprises. 🚀 Let’s dive into how to fix this once and for all!

How to Prevent Content Stripping in WordPress REST API

The first solution I presented involves using the rest_pre_insert_post filter in WordPress. This filter allows developers to modify post data before it is saved in the database via the REST API. By hooking into this filter, you can override WordPress' default sanitization behavior and insert raw content exactly as intended. For example, in the script, we check for a custom field called "content_raw" in the API request, ensuring that the raw HTML content is preserved without being stripped. This is particularly useful for plugins like Kadence, where the layout relies on custom block structures and metadata. 🚀

The second solution introduces a custom REST API endpoint using register_rest_route. This method gives developers complete control over how the post data is processed and stored. In this custom endpoint, the raw content from the API request is directly passed to the WordPress database using the wp_insert_post function. This bypasses default REST API filters and ensures that complex HTML or block configurations are saved without modification. For example, a custom layout created with Kadence blocks will remain intact, even if it includes advanced settings like background images or responsive layouts.

On the frontend, I demonstrated how to use JavaScript to make API requests while preserving raw content. The example uses the fetch API, a modern way to handle HTTP requests in JavaScript. In this scenario, the raw HTML content is passed in the "content" parameter of the POST request, and authentication is handled via a Base64-encoded username and password in the Authorization header. This method is essential for developers building interactive or dynamic frontends that need to push raw content to WordPress without relying on the admin interface.

All the scripts include critical features like error handling and input validation to ensure they work correctly in real-world scenarios. For instance, the custom endpoint uses the is_wp_error function to detect and handle errors, providing meaningful feedback if something goes wrong. This approach guarantees that developers can troubleshoot issues quickly, ensuring seamless content delivery. Imagine creating a visually stunning post layout for a client, only to find it partially stripped in WordPress – these scripts ensure that never happens! 🛠️

// Solution 1: Disable REST API content sanitization and allow raw HTML// Add this code to your WordPress theme's functions.php file<code>add_filter('rest_pre_insert_post', function ($data, $request) {
    // Check for specific custom post type or route
    if (isset($request['content_raw'])) {
        $data['post_content'] = $request['content_raw']; // Set the raw content
    }
    return $data;
}, 10, 2);

// Make sure you’re passing the raw content in your request
// Example POST request:
// In your API request, ensure `content_raw` is passed instead of `content`.
let data = {
    title: 'My Post Title',
    content_raw: my_post,
    status: 'draft'
};
// Send via an authenticated REST client

// Add this code to your theme's functions.php or a custom plugin file<code>add_action('rest_api_init', function () {
    register_rest_route('custom/v1', '/create-post', array(
        'methods' => 'POST',
        'callback' => 'custom_create_post',
        'permission_callback' => '__return_true',
    ));
});
function custom_create_post($request) {
    $post_data = array(
        'post_title' => sanitize_text_field($request['title']),
        'post_content' => $request['content'], // Raw content passed here
        'post_status' => $request['status'],
    );
    $post_id = wp_insert_post($post_data);
    if (is_wp_error($post_id)) {
        return new WP_Error('post_error', 'Failed to create post', array('status' => 500));
    }
    return new WP_REST_Response(array('post_id' => $post_id), 200);
}

// Example using JavaScript to post raw content via the WordPress REST API<code>const rawContent = `<!-- wp:kadence/rowlayout {\"uniqueID\":\"5331_605d8b-3f\"} -->`;
const data = {
    title: "My Custom Post",
    content: rawContent,
    status: "draft"
};
fetch('https://mywp.xyz/wp-json/wp/v2/posts', {
    method: 'POST',
    headers: {
        'Content-Type': 'application/json',
        'Authorization': 'Basic ' + btoa('username:password')
    },
    body: JSON.stringify(data)
})
.then(response => response.json())
.then(data => console.log(data))
.catch(error => console.error("Error:", error));

Understanding WordPress REST API Content Handling

The WordPress REST API is a powerful tool that allows developers to create, read, update, and delete posts programmatically. However, one lesser-discussed aspect is how WordPress processes content before saving it to the database. When using the REST API, WordPress applies a series of filters and sanitization steps to ensure the content is safe and compatible with its internal systems. While this is excellent for security, it can cause issues for developers working with custom HTML or blocks from plugins like Kadence. For example, complex layouts with custom metadata or block configurations may be partially stripped, as WordPress interprets them incorrectly. 🛠️

Another critical factor is how the REST API interacts with dynamic blocks. These blocks are rendered on the frontend using PHP instead of being saved as static HTML. If your custom block isn’t registered properly or the API doesn’t recognize it, some of your block configurations may not save correctly. This happens because WordPress tries to parse and validate the block markup during the save process, which can inadvertently strip out essential parts of your content. To prevent this, it’s important to use proper block registration with attributes that match your API content.

To address these challenges, developers often bypass the standard REST API filters by creating custom endpoints or overriding specific WordPress behaviors. For example, the use of filters like rest_pre_insert_post allows you to inject raw HTML without interference. By carefully tailoring these solutions, you can work around WordPress’ default processing and ensure that your complex layouts and designs remain intact. Imagine creating a stunning banner with a Kadence block, only to see it rendered incorrectly on the frontend – these solutions prevent that from happening! 🚀