Add custom field automatically (add_post_meta) with value based on number of words of article

Question

In this topic our friend @toscho created a function that sets the font size according to the number of words in the post. Based on this function, I want to create a custom field whose value will be set depending on the number of words in the post. For example, if the post contains up to 200 words, automatically create custom field (add_post_meta) with value = 1; If your post contains more than 200 words, create custom field with value = 2.

Any idea is welcome. Thank you.

Answer 1

Hook into save_post, count the words, and update the post meta field.

Sample code, not tested:

add_action( 'save_post', 'wpse_73563_save_word_count', 10, 2 );

function wpse_73563_save_word_count( $post_ID, $post )
{
    if ( ! current_user_can( 'edit_' . $_POST['post_type'], $post_ID ) )
    {
        return FALSE;
    }

    $count = t5_word_count( $post->post_content );

    update_post_meta( $post_ID, '_word_count', ( 200 > $count ? 2 : 1 ) );
}