Wordpress useful functions

1 全局添加图像链接参数

有时候调用Lightbox插件，需要在图片链接上加某些参数，已发布的文章也是，用以下代码添加data-lightbox=“lightbox”（或其他需要的参数）来实现。

/**
 *Lightbox to image link globally
 */
add_filter('the_content', 'dukeyin_addlightbox');
function dukeyin_addlightbox($content) {
       global $post;
       $pattern ="/<a(.*?)href=('|\")(.*?).(bmp|gif|jpeg|jpg|png)('|\")(.*?)>/i";
       $replacement = '<a$1href=$2$3.$4$5 data-lightbox="lightbox" title="'.$post->post_title.'"$6>';
       $content = preg_replace($pattern, $replacement, $content);
       return $content;
}

另一种方式，修改单张图片，也修改相册的链接

<?php
/**
 * Add data attributes for Fancybox
 */
// Gallery images
function ccd_fancybox_gallery_attribute( $content, $id ) {
	// Restore title attribute
	$title = get_the_title( $id );
	return str_replace('<a', '<a data-type="image" data-fancybox="gallery" title="' . esc_attr( $title ) . '" ', $content);
}
add_filter( 'wp_get_attachment_link', 'ccd_fancybox_gallery_attribute', 10, 4 );
// Single images
function ccd_fancybox_image_attribute( $content ) {
       global $post;
       $pattern = "/<a(.*?)href=('|\")(.*?).(bmp|gif|jpeg|jpg|png)('|\")(.*?)>/i";
       $replace = '<a$1href=$2$3.$4$5 data-type="image" data-fancybox="image">';
       $content = preg_replace( $pattern, $replace, $content );
       return $content;
}
add_filter( 'the_content', 'ccd_fancybox_image_attribute' );
?>

2 移除Wordpress版本号

function dk_remove_version() {
return '';
}
add_filter('the_generator', 'dk_remove_version');

3改变默认的Gravatar头像

add_filter( 'avatar_defaults', 'wpb_new_gravatar' );
function wpb_new_gravatar ($avatar_defaults) {
$myavatar = 'http://example.com/wp-content/uploads/2017/01/wpb-default-gravatar.png';
$avatar_defaults[$myavatar] = "Default Gravatar";
return $avatar_defaults;
}

4 手动更新站点地址和首页地址

有时候改变了URL无法登陆Wordpress，需要用ftp更新这两个地址

update_option( 'siteurl', 'http://example.com' );
update_option( 'home', 'http://example.com' );

5添加更多的缩略图尺寸

add_image_size( 'sidebar-thumb', 120, 120, true ); // Hard Crop Mode
add_image_size( 'homepage-thumb', 220, 180 ); // Soft Crop Mode
add_image_size( 'singlepost-thumb', 590, 9999 ); // Unlimited Height Mode

6在RSS输出特色图像

function rss_post_thumbnail($content) {
global $post;
if(has_post_thumbnail($post->ID)) {
$content = '<p>' . get_the_post_thumbnail($post->ID) .
'</p>' . get_the_content();
}
return $content;
}
add_filter('the_excerpt_rss', 'rss_post_thumbnail');
add_filter('the_content_feed', 'rss_post_thumbnail');

7 隐藏登陆错误提示

function no_wordpress_errors(){
  return 'Something is wrong!';
}
add_filter( 'login_errors', 'no_wordpress_errors' );

8默认关闭用Email登陆

remove_filter( 'authenticate', 'wp_authenticate_email_password', 20 );

9 关闭搜索功能

function fb_filter_query( $query, $error = true ) {
 
if ( is_search() ) {
$query->is_search = false;
$query->query_vars[s] = false;
$query->query[s] = false;
 
// to error
if ( $error == true )
$query->is_404 = true;
}
}
 
add_action( 'parse_query', 'fb_filter_query' );
add_filter( 'get_search_form', create_function( '$a', "return null;" ) );

10延迟RSS输出

有时候我们写好一篇文章RSS推送了才发现有错误或者错别字，延迟一点时间有助于我们完善内容。

function publish_later_on_feed($where) {
 
    global $wpdb;
 
    if ( is_feed() ) {
        // timestamp in WP-format
        $now = gmdate('Y-m-d H:i:s');
 
        // value for wait; + device
        $wait = '10'; // integer
 
        // http://dev.mysql.com/doc/refman/5.0/en/date-and-time-functions.html#function_timestampdiff
        $device = 'MINUTE'; //MINUTE, HOUR, DAY, WEEK, MONTH, YEAR
 
        // add SQL-sytax to default $where
        $where .= " AND TIMESTAMPDIFF($device, $wpdb->posts.post_date_gmt, '$now') > $wait ";
    }
    return $where;
}
 
add_filter('posts_where', 'publish_later_on_feed');

11关闭RSS功能

function fb_disable_feed() {
wp_die( __('No feed available,please visit our <a href="'. get_bloginfo('url') .'">homepage</a>!') );
}
 
add_action('do_feed', 'fb_disable_feed', 1);
add_action('do_feed_rdf', 'fb_disable_feed', 1);
add_action('do_feed_rss', 'fb_disable_feed', 1);
add_action('do_feed_rss2', 'fb_disable_feed', 1);
add_action('do_feed_atom', 'fb_disable_feed', 1);

12 改变文章摘要长度

functionnew_excerpt_length($length) {
return 100;
}
add_filter('excerpt_length', 'new_excerpt_length');

13 RSS中不输出特定分类

function exclude_category($query) {
    if ( $query->is_feed ) {
        $query->set('cat', '-5, -2, -3');
    }
return $query;
}
add_filter('pre_get_posts', 'exclude_category');

14 文章Class添加奇偶类

function oddeven_post_class ( $classes ) {
   global $current_class;
   $classes[] = $current_class;
   $current_class = ($current_class == 'odd') ? 'even' : 'odd';
   return $classes;
}
add_filter ( 'post_class' , 'oddeven_post_class' );
global $current_class;
$current_class = 'odd';

这样一来，可以用CSS装饰奇偶文章的不同样式

.even {
background:#f0f8ff;  
} 
.odd {
 background:#f4f4fb;
}

15 自定义后台Logo

function wpb_custom_logo() {
echo '
<style type="text/css">
#wpadminbar #wp-admin-bar-wp-logo > .ab-item .ab-icon:before {
background-image: url(' . get_bloginfo('stylesheet_directory') . '/images/custom-logo.png) !important;
background-position: 0 0;
color:rgba(0, 0, 0, 0);
}
#wpadminbar #wp-admin-bar-wp-logo.hover > .ab-item .ab-icon {
background-position: 0 0;
}
</style>
';
}
//hook into the administrative header output
add_action('wp_before_admin_bar_render', 'wpb_custom_logo');

16 自定义后台底部信息

function remove_footer_admin () {
 
echo 'Fueled by <a href="http://www.wordpress.org" target="_blank">WordPress</a> | WordPress Tutorials: <a href="https://www.wpbeginner.com" target="_blank">WPBeginner</a></p>';
 
}
 
add_filter('admin_footer_text', 'remove_footer_admin');

17自动版权信息

function wpb_copyright() {
global $wpdb;
$copyright_dates = $wpdb->get_results("
SELECT
YEAR(min(post_date_gmt)) AS firstdate,
YEAR(max(post_date_gmt)) AS lastdate
FROM
$wpdb->posts
WHERE
post_status = 'publish'
");
$output = '';
if($copyright_dates) {
$copyright = "© " . $copyright_dates[0]->firstdate;
if($copyright_dates[0]->firstdate != $copyright_dates[0]->lastdate) {
$copyright .= '-' . $copyright_dates[0]->lastdate;
}
$output = $copyright;
}
return $output;
}

18给用户添加自定义后台小面板

add_action('wp_dashboard_setup', 'my_custom_dashboard_widgets');
 
function my_custom_dashboard_widgets() {
global $wp_meta_boxes;
 
wp_add_dashboard_widget('custom_help_widget', 'Theme Support', 'custom_dashboard_help');
}
 
function custom_dashboard_help() {
echo '<p>Welcome to Custom Blog Theme! Need help? Contact the developer <a href="mailto:yourusername@gmail.com">here</a>. For WordPress Tutorials visit: <a href="https://www.wpbeginner.com" target="_blank">WPBeginner</a></p>';
}

19生成随机颜色的函数

function wpb_bg() { 
$rand = array('0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f');
$color ='#'.$rand[rand(0,15)].$rand[rand(0,15)].$rand[rand(0,15)].
$rand[rand(0,15)].$rand[rand(0,15)].$rand[rand(0,15)];
echo $color;
}

在输出颜色出直接“<?php wpb_bg();?>” 即可。略鬼畜慎用。

20 在新窗口打开评论者链接

add_filter( 'get_comment_author_link', 'open_comment_author_link_in_new_window' );
function open_comment_author_link_in_new_window( $author_link ) {
    return str_replace( "

#functions.php

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WordPress useful functions

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