How to send the featured image of a post to an API?

Question

I am currently making a plugin that takes the posts and sends their data to a rest API. Everything else is going smoothly. But I am very confused about how I can achieve this for the featured images. I have to upload a file, not a url. Basically, the API takes multipart/form-data and has an HTTP request method PUT.

The method currently looks something like this:

public function uploadFeaturedImage($post_id)
{   
    $url = build_api_url('posts/' . $post_id. '/photo');
    
    $featured_image_url = get_the_post_thumbnail_url($post_id);
    $image_data =  // Get featured image file here

    $data = array(
        'file' => $image_data
    );

    $args = array(
        'method' => 'PUT',
        'headers' => array('Content-Type' => 'multipart/form-data', 'Authorization' => 'Bearer <token>' ),
        'body' => $data
    );


    $response = wp_remote_request($url,$args);

    return $response['body'];

}

Answer 1

Here is an idea for sending a featured image (file data) on API and setting the image as a featured image on the server.

Get File data from URL using following function:

/*fetch the file from URL*/
function prefix_get_file_data_from_url( $url ) {
    $response = wp_remote_get( $url );
    if ( is_array( $response ) && ! is_wp_error( $response ) ) {
        return wp_remote_retrieve_body( $response );
    }
    return '';
}

After getting the file send it to the server.

On the server end, you will need the following function to upload the file and set it as a featured image.

• $wp_filesystem->put_contents
• wp_insert_attachment

Note: not tested.

Answer 2

Don't know if this is a good approach. But I solved this using curl.

public function uploadFeaturedImage($post_id)
{

    $api_id = $this->get_api_id($post_id);

    $url = blog_transporter_build_api_url('posts/' . $api_id . '/photo');

    $image_url = get_the_post_thumbnail_url($post_id);

    if (empty($image_url)) return false;

    $image_id = get_post_thumbnail_id($post_id);
    $mime_type = get_post_mime_type($image_id);

    $data = array('file' => new CURLFile(
        $image_url,
        $mime_type,
        'featured-image'
    ));

    $headers = array('Authorization: Bearer <token>' , 'Content-Type: multipart/form-data');

    $ch = curl_init($url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "PUT");
    curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
    curl_setopt($ch, CURLINFO_HEADER_OUT, true);
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

    $response = curl_exec($ch);
    return $response;
}