add_action – Page 2 – trepmal.com

Add Links to the Admin Bar

It can be really useful to add some custom links to the Admin Bar. Like, perhaps to the hidden-yet-awesome options.php page.

add_action( 'admin_bar_menu', 'additional_admin_bar_menu', 70 );
function additional_admin_bar_menu( $wp_admin_bar ) {
    if ( current_user_can('manage_options') )
    $wp_admin_bar->add_menu( array( 'id' => 'all-settings', 'title' => __('All Settings'), 'href' => admin_url('options.php') ) );
}

If you want to add a sub-menu item, you must add a “parent” parameter, and its value should match the ID of the parent element.

add_action( 'admin_bar_menu', 'additional_admin_bar_menu_child', 70 );
function additional_admin_bar_menu_child( $wp_admin_bar ) {
        $wp_admin_bar->add_menu( array( 'parent' => 'all-settings', 'id' => 'google', 'title' => __('Google'), 'href' => 'http://google.com' ) );
}

Related Categories for Pages

Just whipped this up as a demo for someone, and thought it would make a great addition here as well.

The idea was to be able to link a category to a page. So if you have a page about Beavers, you can link it to your blog category called Beaver News.

This code is almost a plugin – it will work with some tweaking, but won’t do anything out-of-the-box.

It adds a category selection dropdown to the Edit Page screen, and saves the value as meta. (As-is, you aren’t allowed to not select a category, with a little hacking that should be fixable).

The code at the end includes a demo of how you might use this page meta on the frontend. This code, however, only outputs it in a meta box on the Edit Page screen.

add_action('add_meta_boxes', 'create_box' );
function create_box() {
    add_meta_box( 'related_category', 'Related Category', 'box_html', 'page', 'side');
}

function box_html() {
    global $post;
    $selected = get_post_meta( $post->ID, '_related_category', true );
    wp_nonce_field( plugin_basename(__FILE__), 'related_cat_nonce' );
    wp_dropdown_categories( array('hide_empty' => false, 'show_count' => true, 'name' => 'related_cat', 'selected' => $selected ) );
}

add_action('save_post', 'save_box' );
function save_box( $post_id ) {

    if ( !wp_verify_nonce( $_POST['related_cat_nonce'], plugin_basename(__FILE__) ) )
        return $post_id;

    if ( defined('DOING_AUTOSAVE') && DOING_AUTOSAVE ) 
        return $post_id;

    if ( 'page' == $_POST['post_type'] && !current_user_can( 'edit_page', $post_id ) )
        return $post_id;
    
    if (!isset($_POST['related_cat']))
        return $post_id;
    else {
        $related_cat = $_POST['related_cat'];
        update_post_meta( $post_id, '_related_category', $related_cat, get_post_meta( $post_id, '_related_category', true ) );
    }
    
}

// this just puts the feed in a meta box on the appropriate page
// it can be ripped out and added to the page template
add_action('add_meta_boxes', 'create_box_display' );
function create_box_display() {
    add_meta_box( 'related_category_display', 'Related Category Display', 'box_html_display', 'page', 'side');
}

function box_html_display() {
    global $post;
    $selected = get_post_meta( $post->ID, '_related_category', true );
    $related = get_posts('numberposts=5&category='.$selected);
    foreach($related as $p) {
        echo '<h4>'.$p->post_title.'</h4>';
        echo wpautop($p->post_content);
        echo '<hr />';
    }
}

Override Rich Edit Setting

It’s very easy to override the user-selected rich edit setting. Whether they’ve selected to show it or hide it, it can be reversed in a single line of code:

Always show:

add_filter( 'user_can_richedit', '__return_true' );

Always hide:

add_filter( 'user_can_richedit', '__return_false' );

Of course, if you’re going to overwrite this setting, it would make sense to also hide the user’s checkbox for this option.

add_action( 'admin_print_styles-profile.php', 'hide_rich_edit_option' );
add_action( 'admin_print_styles-user-edit.php', 'hide_rich_edit_option' );
function hide_rich_edit_option() {
    ?><style type="text/css">
    label[for=rich_editing] input { display: none; }
    label[for=rich_editing]:before { content: 'This option has been disabled (Formerly: ' }
    label[for=rich_editing]:after { content: ')'; }
    </style><?php
}

You can probably remove it more fully with Javascript, but I’ll leave that up to you.

Redirect Users to a Custom Log In Page

Relevant for WordPress 4.4: https://core.trac.wordpress.org/ticket/35103

If you’ve created a login page that isn’t at /wp-login.php, here’s a simple way you can redirect users who click on the “Log In” links to your new page:

add_filter( 'login_url', 'new_login_url', 10, 2 );
function new_login_url( $login_url, $redirect ) {
    return '/log-in/';
}

Add the “Lost Password?” Link to wp_login_form() Output

If you’re using the handy wp_login_form() function to create a custom log in page, you may have noticed that you don’t get the “Lost Password?” link. Doesn’t take much to add it back:

add_action( 'login_form_middle', 'add_lost_password_link' );
function add_lost_password_link() {
	return '<a href="/wp-login.php?action=lostpassword">Lost Password?</a>';
}

Disable Login Errors and Messages

If you want to make is it so that a user doesn’t know why a failed login failed, you can use these 2 lines of code. Useful if you’re the only user and you don’t want to give potential hackers any extra info. For example, if you have the right username but a bad password, by default it will tell you in the error message – letting the person know they have half the info correct. If a username doesn’t exist, that information is also revealed.

add_filter( 'login_errors', '__return_false' );
add_filter( 'login_messages', '__return_false' );

You might want to add a little CSS to make sure the empty error/message boxes don’t show up either:

add_action( 'login_head', 'login_head_css' );
function login_head_css() {
    ?><style type="text/css">.message, #login_error { display:none; }</style><?php
}

Redirect All Logged-Out Users to Log In Screen

If you’re running a private blog and you want to make sure all logged-out visitors are redirected to the sign-in page, this will do the trick.

add_action( 'template_redirect', 'logged_in_users_only' );
function logged_in_users_only() {
	if ( !is_user_logged_in() )
	wp_redirect( wp_login_url() );
}

If you want users to come back to the front page after logging in, you can pass an argument to the wp_login_url() function.

add_action( 'template_redirect', 'logged_in_users_only' );
function logged_in_users_only() {
	if ( !is_user_logged_in() )
	wp_redirect( wp_login_url( home_url() ) );
}

This will only redirect users who were initially redirected to the login screen from the front-end. If the user went directly to the login screen – the filter above won’t have been triggered, so they’ll be taken to the administration side.

Use a Custom Field to Add to the

I needed a very simple way to custom styles or scripts to the <head>, and I didn’t really want to customize the theme.

add_action( 'wp_head', 'wp_head_custom_field' );
function wp_head_custom_field() {
    if ( is_single() ) {
        global $post;
        $html = get_post_meta( $post->ID, 'wp_head', true );
        echo $html;
    }
}

With this, I just needed to add my pre-formatted javascript or css to a custom field called ‘wp_head’ and it would then be added to the <head> just like I needed. I added the is_single() as a precaution.

Swap Color Schemes When Switching Between Network and Site Admins

I wanted to find a way to make it just a little bit more obvious when I switched between the network and site admins. But I didn’t want to have to do a lot of actual customizing. So using built in styles, I found I could just swap the color schemes.

add_action( 'admin_print_styles', 'admin_color_swap', 99 );
function admin_color_swap() {
    if ( is_network_admin() ) {
        global $current_user;
        get_currentuserinfo();
        $selected = $current_user->admin_color;
        $swapped = array( 'fresh' => 'classic', 'classic' => 'fresh' );
        $new = $swapped[$selected];        
        echo '<link rel="stylesheet" type="text/css" href="/wp-admin/css/colors-'.$new.'.css" />';
    }
}

Add Post Options To “Publish” Meta Box

We often add custom meta boxes to a page or post in order to save specific kinds of data. In some cases, the best place to add those fields really isn’t in some box that gets added to the end of the page. The option needs to be in a bit more prominent location.

Fortunately, it’s possible to add text or form elements to the “Publish” meta box.

add_action( 'post_submitbox_misc_actions', 'article_or_box' );
add_action( 'save_post', 'save_article_or_box' );
function article_or_box() {
    global $post;
    if (get_post_type($post) == 'post') {
        echo '<div class="misc-pub-section misc-pub-section-last" style="border-top: 1px solid #eee;">';
        wp_nonce_field( plugin_basename(__FILE__), 'article_or_box_nonce' );
        $val = get_post_meta( $post->ID, '_article_or_box', true ) ? get_post_meta( $post->ID, '_article_or_box', true ) : 'article';
        echo '<input type="radio" name="article_or_box" id="article_or_box-article" value="article" '.checked($val,'article',false).' /> <label for="article_or_box-article" class="select-it">Article</label><br />';
        echo '<input type="radio" name="article_or_box" id="article_or_box-box" value="box" '.checked($val,'box',false).'/> <label for="article_or_box-box" class="select-it">Box</label>';
        echo '</div>';
    }
}
function save_article_or_box($post_id) {

    if (!isset($_POST['post_type']) )
        return $post_id;

    if ( !wp_verify_nonce( $_POST['article_or_box_nonce'], plugin_basename(__FILE__) ) )
        return $post_id;

    if ( defined('DOING_AUTOSAVE') && DOING_AUTOSAVE ) 
        return $post_id;

    if ( 'post' == $_POST['post_type'] && !current_user_can( 'edit_post', $post_id ) )
        return $post_id;
    
    if (!isset($_POST['article_or_box']))
        return $post_id;
    else {
        $mydata = $_POST['article_or_box'];
        update_post_meta( $post_id, '_article_or_box', $_POST['article_or_box'], get_post_meta( $post_id, '_article_or_box', true ) );
    }

}

What I needed at one time was a way to mark a post that would determine whether it would be displayed in a regular article style, or in a special box style. Nowadays, I can use post formats. But the point is, you could put other options there. Perhaps an expiration date field.