Perhaps you need to provide a little extra instruction about the Featured Image meta box. It doesn’t take much to add your own text to that box:
add_filter( 'admin_post_thumbnail_html', 'add_featured_image_instruction');
function add_featured_image_instruction( $content ) {
return $content .= '<p>The Featured Image is an image that is chosen as the representative image for Posts or Pages. Click the link above to add or change the image for this post. </p>';
}
If you need to add a simple warning or error notice to the WordPress admin area, or if you just to to make a small announcement to the site users, you can do so pretty easily.
add_action('admin_notices','simple_announcement');
function simple_announcement() {
?><div class="updated">
<p>hello</p>
</div><?php
}
Here’s a bit of code that will allow you to add a footnote to your post – inline. It’s easy enough to add footnotes manually, sure. But where’s the fun in that?
add_shortcode( 'footnote', 'footnote_shortcode' );
function footnote_shortcode( $atts, $content ) {
extract(shortcode_atts( array() , $atts));
global $post;
update_post_meta( $post->ID, '_footnote', $content, get_post_meta( $post->ID, '_footnote', true ) );
return ' <a href="#fn_'.$post->ID.'">*</a> ';
}
add_filter( 'the_content', 'append_footnote' );
function append_footnote($content) {
global $post;
if ( get_post_meta( $post->ID, '_footnote', true ) != '' )
$content .= '<p id="fn_'.$post->ID.'">* '.get_post_meta( $post->ID, '_footnote', true ) .'</p>';
return $content;
}
A footnote could then be added like this:
The moon is 384,403 km [footnote]238,857 miles[/footnote] from the earth.
There might be a better way to append the footnote to the end – so feel free to investigate and improve.
Sometimes, the ability to add multiple categories to a single post can cause problems. Or maybe you’re working with custom taxonomies and you need to make sure only one term is assigned to a post. Assuming you’re creating your own alternative category selection box, you can use this to get red of the default meta box.
add_action('admin_init','remove_cat_box');
function remove_cat_box() {
//args: $categoryslug.'div', $posttype, $location
remove_meta_box('categorydiv', 'post', 'side');
}
For a variety of reasons, you may not be able to add content directly to the WordPress editor. Maybe it’s funky code that’ll get stripped out, or you want a random quote to show up, or it’s some other kind of dynamic content.
That’s what shortcodes are good for! Here’s a simple one that creates a ‘youtube’ shortcode for embedding videos in your post.
add_shortcode( 'youtube', 'youtube_shortcode' );
function youtube_shortcode( $atts ) {
extract( shortcode_atts( array('id' => '', 'width' => 480, 'height' => 390) , $atts ) );
$id = trim($id);
if (empty($id)) return;
return '<iframe title="YouTube video player" width="'. $width .'" height="'. $height .'" src="http://www.youtube.com/embed/'. $id .'" frameborder="0" allowfullscreen></iframe>';
}
Used in your post like this: [youtube id="a1Y73sPHKxw"]. The width and height attributes will default to 480 and 390 respectively if not specified in the shortcode. Quotes around the attribute value are not required unless your value has a space.
If you’re not thrilled with the provided options for a default avatar, you can use this to quickly add your own image to the list.
add_filter( 'avatar_defaults', 'addavatar' );
function addavatar ( $avatar_defaults ) {
$avatar_defaults[ 'http://placekitten.com/512/512' ] = 'Placekitten';
return $avatar_defaults;
}
Need to declutter the profile options by removing the various IM fields. It’s easy
add_filter('user_contactmethods', 'remove_im_options', 10, 2);
function remove_im_options( $user_contactmethods, $user ) {
unset($user_contactmethods['aim']);
unset($user_contactmethods['yim']);
unset($user_contactmethods['jabber']);
//$user_contactmethods = array();
return $user_contactmethods;
}
I’m working on a plugin right now where I’m having to hide or limit a lot of features depending on the current user’s capabilities. Among those limitations is media uploading and editing access. I’m using this snippet to hide the Media Library tab from the Add an Image pop-up on the edit post page.
add_filter('media_upload_tabs','no_library_tab');
function no_library_tab($tabs) {
if (!current_user_can('promote_users')) {
unset($tabs['library']);
}
return $tabs;
}
If you need to hand over the reins to a client, but want to make sure certain options stay unchanged, you can add this code:
add_filter( 'pre_update_option_admin_email', 'prevent_option_change', 10, 2 );
function prevent_option_change( $newvalue, $oldvalue ) {
return $oldvalue;
}
In this case, I’m preserving ‘admin_email’ – just change that part of the filter hook to preserve another option.
I don’t have a good example of why you might want or need this, but nevertheless, if you should want to add additional text to the Widgets admin, it’s pretty darn easy:
add_action( 'widgets_admin_page', 'widgets_admin_info' );
function widgets_admin_info() {
?>
<p style="clear:both;">Hello there!!</p>
<?php
}