How to avoid an infinite loop when WordPress uses hooks for theme development

The following tutorial column of WordPress will introduce to you how to avoid an infinite loop when WordPress uses hooks for theme development. I hope it will be helpful to friends in need!

WordPress avoids endless loops when using hooks for theme development

When developing WordPress, we often use hooks such as save_post or create_post_tag , so that some additional data can be added when updating articles or categories. The timing of these hooks being triggered is the time when data is published or updated. If not handled well, an infinite loop will occur, resulting in an infinite loop when updating data.

For example, when saving an article, we need to hang a function on the save_post hook. The purpose of this function is to modify the article title and add the author's name in front of the article title. , we display this modification by calling the wp_update_post function. Sample code is as follows.

add_action('save_post', 'wprs_update_post');
function wprs_update_post($post_id)
{
    $title = get_the_title($post_id);
    $title = "一刀：" . $title;

    $args = [
        'ID'         => $post_id,
        'post_title' => $title,
    ];
    
    wp_update_post($args);
}

In the above code, the "save_post" hook occurs during the calling process of the wp_update_post function. Through the "save_post" hook, we call the wp_update_post function. In this function, "save_post" is run again. hook. As a result, the program continued to run tirelessly.

Experienced programmers may easily discover this problem, but the computer does not know that this is an infinite loop. We cannot blame the computer, after all, it is just a mindless machine. What we can do is to be as careful as possible during the development process to avoid the occurrence of infinite loops.

So, how to solve this infinite loop in WordPress? In fact, the method is very simple.

How to avoid the infinite loop in WordPress

It’s still the above code. With a slight modification, we can perfectly avoid this infinite loop. The following is the modified code. Compared with the infinite loop code above, we only added two lines.

add_action('save_post', 'wprs_update_post');
function wprs_update_post($post_id)
{
   // 获取文章标题并在文章标题前面加上作者
    $title = get_the_title($post_id);
    $title = "一刀：" . $title;

    $args = [
        'ID'         => $post_id,
        'post_title' => $title,
    ];
    
    // 更新文章
    remove_action('save_post', 'wprs_update_post');
    wp_update_post($args);
    add_action('save_post', 'wprs_update_post');
}

The principle is very simple. Before running the "wp_update_post" function, we first uninstall the function that hangs on the "save_post" hook and causes an infinite loop, so that there will be no repeated execution of the "wprs_update_post" function. After updating the article, we will mount this hook for subsequent use.

If you encounter an infinite loop problem during WordPress development, you may wish to refer to the above code and modify it, so that the functions we need can be achieved without causing an infinite loop problem.

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