20 Time Saving Code Snippets for WordPress Developers

When working on WordPress themes, it’s really useful to have a collection of code snippets in your code library to just copy and paste when a particular functionality needed. These code snippets can save your lots of time and speed up development. As we know that WordPress has a huge community which published tons of super handy code snippets and tips to help developers. Here in this post, I have compiled some of my favourite WordPress code snippets which surely extend functionality and save your precious time when developing WordPress themes.

All of these code snippets are simply cut-and-paste solutions for your theme’s functions.php file.

Display lightbox with all images embedded in a post

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

Get related posts by posts current author

function get_related_author_posts() {
    global $authordata, $post;
    $authors_posts = get_posts( array( 'author' => $authordata->ID, 
'post__not_in' => array( $post->ID ), 'posts_per_page' => 10 ) );
    $output = '<ul>';
    foreach ( $authors_posts as $authors_post ) {
        $output .= '<li><a href="' . get_permalink( $authors_post->ID 
) . '">' . apply_filters( 'the_title', $authors_post->post_title,
 $authors_post->ID ) . '< /a>< /li>';
    }
    $output .= '< /ul>';
    return $output;
}

Get total number of images in media library

function get_image_count(){
	$query_img_args = array(
		'post_type' => 'attachment',
		'post_mime_type' =>array(
                		'jpg|jpeg|jpe' => 'image/jpeg',
                		'gif' => 'image/gif',
				'png' => 'image/png',
				),
		'post_status' => 'inherit',
		'posts_per_page' => -1,
		);
	$query_img = new WP_Query( $query_img_args );
	echo $query_img->post_count;
}

Restrict wp-admin access to subscribers

function restrict_access_admin_panel(){
	global $current_user;
	get_currentuserinfo();
	if ($current_user->user_level <  4) {
		wp_redirect( get_bloginfo('url') );
		exit;
	}
}
add_action('admin_init', 'restrict_access_admin_panel', 1);

Increase the excerpt field height

add_action('admin_head', 'excerpt_textarea_height');
function excerpt_textarea_height() {
    echo'
    <style type="text/css">
        #excerpt{ height:400px; }
    </style>
    ';
}

Automatically add the Google +1 button

add_filter('the_content', 'add_google_plusone');
function add_google_plusone($content) {
	$content = $content.'

‘; return $content; } add_action (‘wp_enqueue_scripts’,’google_plusone_script’); function google_plusone_script() { wp_enqueue_script(‘google-plusone’, ‘https://apis.google.com/js/plusone.js’, array(), null); }

Limit search to specific post types

function limitPostSearch($query) { 
if ($query->is_search) { 
$query->set('post_type',array('post','page')); 
} 
return $query; 
} 

add_filter('pre_get_posts','limitPostSearch');

Automatically spam comments with a very long url

function check_spam( $approved , $commentdata ) {
    return ( strlen( $commentdata['comment_author_url'] ) > 50 ) ? 'spam'
 : $approved;
  }
  add_filter( 'pre_comment_approved', 'check_spam', 99, 2 );

Add custom text to WordPress login page

function add_login_message( $message ) {
    if ( empty($message) ){
        return "<p class='message'>Welcome to this site. Please log in 
to continue</p>";
    } else {
        return $message;
    }
}
add_filter( 'login_message', 'add_login_message' );

Force specific WordPress pages to be SSL secure

function force_page_ssl( $force_ssl, $post_id = 0, $url = '' ) {
    if ( $post_id == 25 ) {
        return true
    }
    return $force_ssl;
}
add_filter('force_ssl' , 'force_page_ssl', 10, 3);

Clean up wp_head() without a plugin

remove_action( 'wp_head', 'rsd_link' );
remove_action( 'wp_head', 'wlwmanifest_link' );
remove_action( 'wp_head', 'wp_generator' );
remove_action( 'wp_head', 'start_post_rel_link' );
remove_action( 'wp_head', 'index_rel_link' );
remove_action( 'wp_head', 'adjacent_posts_rel_link' );
remove_action( 'wp_head', 'wp_shortlink_wp_head' );

Automatically link Twitter usernames in WordPress

function twtreplace($content) {
	$twtreplace = preg_replace('/([^a-zA-Z0-9-_&])@([0-9a-zA-Z_]+)/',"$1
 <a href=\"http://twitter.com/$2\" target=\"_blank\" rel=\"nofollow\">@$2</a>
",$content);
	return $twtreplace;
}

add_filter('the_content', 'twtreplace');   
add_filter('comment_text', 'twtreplace');

Redirect WordPress Feeds to Feedburner

add_action('template_redirect', 'rss_redirect');
function rss_redirect() {
	if ( is_feed() && !preg_match('/feedburner|feedvalidator/i'
, $_SERVER['HTTP_USER_AGENT'])){
		header('Location: http://feeds.feedburner.com/yourfeedname');
		header('HTTP/1.1 302 Temporary Redirect');
	}
}

Email contributors when posts published

function email_notification($post_id) {
   $post = get_post($post_id);
   $author = get_userdata($post->post_author);

   $message = "
      Hi ".$author->display_name.",
      Your post, ".$post->post_title." has just been published. Well done!
   ";
   wp_mail($author->user_email, "Your article is online", $message);
}
add_action('publish_post', 'email_notification');

Add a Favicon

add_action( 'wp_head', 'add_favicon');
function add_favicon(){
	echo " <link href="" . get_stylesheet_directory_uri() . 
"/favicon.ico" rel="shortcut icon"  />" . "\n";
}

Shortcode to Display External Files

function show_external_file( $atts ) {
  extract( shortcode_atts( array(
    'file' => ''
  ), $atts ) );

  if ($file!='')
    return @file_get_contents($file);
}

add_shortcode( 'show_file', 'show_external_file' );

Create Custom Shortcodes

function show_message() {
return 'Hi How Are You!';
}
add_shortcode('message', 'show_message');

You can then use [message] wherever you want to display the content of the shortcode.

Add Content to the End of Each RSS Post

function feedFilter($query) {
    if ($query->is_feed) {
        add_filter('the_content','feedContentFilter');
    }
    return $query;
}
add_filter('pre_get_posts','feedFilter');

function feedContentFilter($content) {
    $content .= 'Extra RSS content goes here... ';

    return $content;
}

Detect which browser your visitors are using

add_filter('body_class','browser_body_class');
function browser_body_class($classes) {
global $is_lynx, $is_gecko, $is_IE, $is_opera, $is_NS4, $is_safari, 
$is_chrome, $is_iphone;
if($is_lynx) $classes[] = 'lynx';
elseif($is_gecko) $classes[] = 'gecko';
elseif($is_opera) $classes[] = 'opera';
elseif($is_NS4) $classes[] = 'ns4';
elseif($is_safari) $classes[] = 'safari';
elseif($is_chrome) $classes[] = 'chrome';
elseif($is_IE) $classes[] = 'ie';
else $classes[] = 'unknown';
if($is_iphone) $classes[] = 'iphone';
return $classes;
}

Insert Author Bio for Each Post

function display_author_bio ($content=''){
    global $post;

    $post_author_name=get_the_author_meta("display_name");
    $post_author_description=get_the_author_meta("description");
    $html="<div class='clearfix' id='about_author'>\n";
    $html.="<img width='80' height='80' class='avatar' 
src='https://www.gravatar.com/avatar.php?gravatar_id=".md5(get_the_author_email())
. "&default=".urlencode($GLOBALS['defaultgravatar'])."&size=80&r=PG' alt='PG'/>\n";
    $html.="<div class='author_text'>\n";
    $html.="<h4>Author: ".$post_author_name."</h4>\n";
    $html.= $post_author_description."\n";
    $html.="</div>\n";
    $html.="<div class='clear'></div>\n";
    $content .= $html;
    }

    return $content;
}

add_filter('the_content', 'display_author_bio');