我会wp_insert_post_data 过滤并尽可能少地处理这一问题，因为据我所知，您不想阻止帖子的插入，只想避免发布具有重复元值的帖子。

在这种情况下，我不能浪费太多时间，因为您没有共享任何代码，但这里有一些过滤器的伪代码可以工作：

function wp8193131_check_if_meta_value_is_unique ( $data, $postarr ) {
    // setup an uniqueness flag.
    $meta_is_unique = true;

    // check if the meta is unique and modify the `$meta_is_unique` flag accordingly.
    // {...} <- your code

    // if the meta is NOT unique keep the post status in draft.
    if ( ! $meta_is_unique ) {
        // you can force the current post to be draft until the meta value will became unique.
        $data[\'post_status\'] = \'draft\';
        // maybe, update the meta value with a hint of the fact that it\'s not unique.
        // or display a dashboard notice about it.
    }

    return $data;
}
add_filter( \'wp_insert_post_data\', \'wp8193131_check_if_meta_value_is_unique\' );

我希望这有帮助，无论你做什么，听起来都很棒！

在提交文章进行发布之前，使用AJAX检查其唯一性如何？

$( \'#post\' ).on( \'submit\', function( event ) {
  event.preventDefault(); // Prevent publishing

  //Now do some AJAX Checks
  $.post( ajaxurl, data, function(response) {
    if ( response === \'success\' ) {
        $( this ).off( event ).submit();
    } else {
        alert( \'The custom field must be unique\' );
    }
  });
});  

支票应转到wp_insert_post. 每当发布或编辑帖子时，就会触发此挂钩。

在那里，您可以进行自定义查询以检查是否有任何帖子已经具有相同的内容xxxx_url 值或否。

add_action(\'wp_insert_post\', function($post_id) {
    $meta_key = \'xxxx_url\';
    $meta_value = get_post_meta($post_id, $meta_key, true);
    $query = new WP_Query([
        \'post_type\' => get_post_type($post_id),     // This might be unnecessary, if you check `post` post type only. Or use `any`.
        \'meta_query\' => [
            [
                \'meta_key\' => $meta_key,
                \'meta_value\' => $meta_value,
            ]
        ]
    ]);
    if ($query->have_posts()) {
        // invalid key, post with the same value already exists
    } else {
        // valid, key was not found anywhere
    }
});