WordPress:Conditional Tags

Introduction

The Conditional Tags can be used in your Template files to change what content is displayed and how that content is displayed on a particular page depending on what conditions that page matches. For example, you might want to display a snippet of text above the series of posts, but only on the main page of your blog. With the [[WordPress:#The Main Page|is_home()]] Conditional Tag, that task is made easy.

Note the close relation these tags have to WordPress' WordPress:Template Hierarchy.

The Conditions For...

All of the Conditional Tags test to see whether a certain condition is met, and then returns either TRUE or FALSE. The conditions under which various tags output TRUE is listed below. Those tags which can accept parameters are so noted.

The Main Page

is_home(): When the main blog page is being displayed. (Wordpress 2.1 handles this function differently than prior versions. See static Front Page.)

Note: If you select a static Page as your frontpage (see below), this tag will be applied to your "posts page".

The Front Page

is_front_page(): When it is the front of the site displayed, whether it is posts or a Page. Returns true when the main blog page is being displayed and the 'Settings->Reading->Front page displays' is set to "Your latest posts", or when 'Settings->Reading->Front page displays' is set to "A static page" and the "Front Page" value is the current Page being displayed. Note: this tag was added at WordPress:Version 2.5.

The Administration Panels

is_admin(): When the Dashboard or the administration panels are being displayed.

A Single Post Page

is_single(): When any single Post page is being displayed.
is_single('17'): When Post 17 is being displayed as a single Post.
is_single('Irish Stew'): When the Post with Title "Irish Stew" is being displayed as a single Post.
is_single('beef-stew'): When the Post with Post Slug "beef-stew" is being displayed as a single Post.
is_single(array(17,'beef-stew','Irish Stew')): Returns true when the single post being displayed is either post ID 17, or the post_name is "beef-stew", or the post_title is "Irish Stew". Note: the array ability was added at WordPress:Version 2.5.

Any Page Containing Posts

comments_open(): When comments are allowed for the current Post being processed in the WordPress Loop.
pings_open(): When pings are allowed for the current Post being processed in the WordPress Loop.

A PAGE Page

This section refers to WordPress WordPress:Pages, not any generic webpage from your blog.

is_page(): When any Page is being displayed.
is_page('42'): When Page 42 (ID) is being displayed.
is_page('About Me And Joe'): When the Page with a post_title of "About Me And Joe" is being displayed.
is_page('about-me'): When the Page with a post_name (slug) of "about-me" is being displayed.
is_page(array(42,'about-me','About Me And Joe')): Returns true when the Pages displayed is either post ID 42, or post_name "about-me", or post_title "About Me And Joe". Note: the array ability was added at WordPress:Version 2.5.

Testing for sub-Pages

There is no is_subpage() function yet, but you can test this with a little code:

<?php
// Get $post if you're inside a function
global $post;

if (is_page() && $post->post_parent ) {
	// This is a subpage
} else {
	// This is not a subpage
}
?>

If you need to test whether this is a particular page OR a child of that page (e.g. to present a different banner on different sections of a page-based site), get the parent page IDs from the back-end, then use code like this:

<?php

if 	(is_page(about) || $post->post_parent=="2") { 
	$bannerimg="home.jpg"; 
} elseif (is_page(learning) || $post->post_parent=="56") {	
	$bannerimg="teaching.jpg"; 
} elseif (is_page(admissions) || $post->post_parent=="15") { 
	$bannerimg="admissions.jpg";	
} else { 
	$bannerimg="home.jpg" ; // Fall-through  
}	

?>

Is a Page Template

Beginning with WordPress:Version 2.5 this allows you to determine whether or not you are in a page template or if a specific page template is being used.

is_page_template(): Is a Page Template being used?
is_page_template('about.php'): Is Page Template 'about' being used? Note that unlike with other conditionals, if you want to specify a particular Page Template, you need to use the filename, such as about.php or my_page_template.php.

A Category Page

is_category(): When any Category archive page is being displayed.
is_category('9'): When the archive page for Category 9 is being displayed.
is_category('Stinky Cheeses'): When the archive page for the Category with Name "Stinky Cheeses" is being displayed.
is_category('blue-cheese'): When the archive page for the Category with Category Slug "blue-cheese" is being displayed.
is_category(array(9,'blue-cheese','Stinky Cheeses')): Returns true when the category of posts being displayed is either term_ID 9, or slug "blue-cheese", or name "Stinky Cheeses". Note: the array ability was added at WordPress:Version 2.5.
in_category('5'): Returns true if the current post is in the specified category id. read more

Note: Be sure to check your spelling when testing, "is" and "in" are a big difference.

See also [[WordPress:#Any Archive Page|is_archive()]] and WordPress:Category Templates.

A Tag Page

is_tag(): When any Tag archive page is being displayed.
is_tag('mild'): When the archive page for tag with the slug of 'mild' is being displayed.
is_tag(array('sharp','mild','extreme')): Returns true when the tag archive being displayed has a slug of either "sharp", "mild", or "extreme". Note: the array ability was added at WordPress:Version 2.5.

See also [[WordPress:#Any Archive Page|is_archive()]] and WordPress:Tag Templates.

An Author Page

is_author(): When any Author page is being displayed.
is_author('4'): When the archive page for Author number (ID) 4 is being displayed.
is_author('Vivian'): When the archive page for the Author with Nickname "Vivian" is being displayed.
is_author('john-jones'): When the archive page for the Author with Nicename "john-jones" is being displayed.
is_author(array(4,'john-jones','Vivian')): When the archive page for the author is either user ID 4, or user_nicename "john-jones", or nickname "Vivian". Note: the array ability was added at WordPress:Version 2.5.

See also [[WordPress:#Any Archive Page|is_archive()]] and WordPress:Author Templates.

A Date Page

is_date(): When any date-based archive page is being displayed (i.e. a monthly, yearly, daily or time-based archive).
is_year(): When a yearly archive is being displayed.
is_month(): When a monthly archive is being displayed.
is_day(): When a daily archive is being displayed.
is_time(): When an hourly, "minutely", or "secondly" archive is being displayed.

See also [[WordPress:#Any Archive Page|is_archive()]].

Any Archive Page

is_archive(): When any type of Archive page is being displayed. Category, Author and Date based pages are all types of Archives.

A Search Result Page

is_search(): When a search result page archive is being displayed.

A 404 Not Found Page

is_404(): When a page displays after an "HTTP 404: Not Found" error occurs.

A Paged Page

is_paged(): When the page being displayed is "paged". This refers to an archive or the main page being split up over several pages. This does not refer to a Post or Page whose content has been divided into pages using the  QuickTag.

An Attachment

is_attachment(): When an attachment document to a post or Page is being displayed. An attachment is an image or other file uploaded through the post editor's upload utility. Attachments can be displayed on their own 'page' or template. For more information, see WordPress:Using Image and File Attachments.

A Syndication

is_feed(): When the site requested is a Syndication. This tag is not typically used by users; it is used internally by WordPress and is available for Plugin Developers.

A Trackback

is_trackback(): When the site requested is WordPress' hook into its Trackback engine. This tag is not typically used by users; it is used internally by WordPress and is available for Plugin Developers.

A Preview

is_preview(): When a single post being displayed is viewed in Draft mode.

Has An Excerpt

!empty($post->post_excerpt): There is no built-in way to check if a post has an excerpt, but you can use the above code in the same way. Remove the '!' to emulate 'has_no_excerpt'.

Working Examples

Here are working samples to demonstrate how to use these conditional tags.

Single Post

This example shows how to use is_single() to display something specific only when viewing a single post page:

if (is_single())
{
     echo 'This is just one of many fabulous entries in the ' . single_cat_title() . ' category!';
}

Date-Based Differences

If someone browses our site by date, let's distinguish posts in different years by using different colors:

<?php
// this starts The Loop
if ( have_posts() ) : while ( have_posts() ) : the_post(); ?>
<h2 id="post-<?php the_ID(); ?>">
<a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title(); ?>">
<?php the_title(); ?></a></h2>
<small><?php the_time('F jS, Y') ?> <!-- by <?php the_author() ?> --></small>

<?php
// are we showing a date-based archive?
if (is_date())
{
     if (date('Y') != get_the_date('Y'))
     {
          // this post was written in a previous year
          // so let's style the content using the "oldentry" class
          echo '<div class="oldentry">';
     } else {
          echo '<div class="entry">';
     }
} else {
     echo '<div class="entry">';
}
the_content('Read the rest of this entry »'); 
?>
</div>

Variable Sidebar Content

This example will display different content in your sidebar based on what page the reader is currently viewing.

<!-- begin sidebar -->
<div id="sidebar">
<?php
// let's generate info appropriate to the page being displayed
if (is_home()) {
        // we're on the home page, so let's show a list of all top-level categories
        echo "<ul>";
        wp_list_cats('optionall=0&sort_column=name&list=1&children=0');
        echo "</ul>";
} elseif (is_category()) {
        // we're looking at a single category view, so let's show _all_ the categories
         echo "<ul>";
        wp_list_cats('optionall=1&sort_column=name&list=1&children=1&hierarchical=1');
        echo "</ul>";
} elseif (is_single()) {
        // we're looking at a single page, so let's not show anything in the sidebar
} elseif (is_page()) {
        // we're looking at a static page.  Which one?
        if (is_page('About')) {
             // our about page.
             echo "<p>This is my about page!</p>";
        } elseif (is_page('Colophon')) {
             echo "<p>This is my colophon page, running on WordPress " . bloginfo('version') . "</p>";
        } else {
              // catch-all for other pages
              echo "<p>Vote for Pedro!</p>";
        }
} else {
        // catch-all for everything else (archives, searches, 404s, etc)
        echo "<p>Pedro offers you his protection.</p>";
} // That's all, folks!
?>
<form id="searchform" method="get" action="<?php echo $_SERVER['PHP_SELF']; ?>">
<div>
<input type="text" name="s" id="s" size="15" />
<input type="submit" value="<?php _e('Search'); ?>" />
</div>
</form>

</div>
<!-- end sidebar -->

Helpful 404 page

When a visitor gets a 404 error page, it can be intimidating, and unhelpful. Using Wordpress, you can take the edge off a 404 and make it helpful to users, and yourself, too, by emailing whenever the user clicks a link to a non-existent page. If you use this, don't forget o

<p>You 
<?php
#some variables for the script to use
#if you have some reason to change these, do.  but wordpress can handle it
$adminemail = get_bloginfo('admin_email'); #the administrator email address, according to wordpress
$website = get_bloginfo('url'); #gets your blog's url from wordpress
$websitename = get_bloginfo('name'); #sets the blog's name, according to wordpress

  if (!isset($_SERVER['HTTP_REFERER'])) {
    #politely blames the user for all the problems they caused
        echo "tried going to "; #starts assembling an output paragraph
	$casemessage = "All is not lost!";
  } elseif (isset($_SERVER['HTTP_REFERER'])) {
    #this will help the user find what they want, and email me of a bad link
	echo "clicked a link to"; #now the message says You clicked a link to...
        #setup a message to be sent to me
	$failuremess = "A user tried to go to $website"
        .$_SERVER['REQUEST_URI']." and received a 404 (page not found) error. ";
	$failuremess .= "It wasn't their fault, so try fixing it.  
        They came from ".$_SERVER['HTTP_REFERER'];
	mail($adminemail, "Bad Link To ".$_SERVER['REQUEST_URI'],
        $failuremess, "From: $websitename <noreply@$website>"); #email you about problem
	$casemessage = "An administrator has been emailed 
        about this problem, too.";#set a friendly message
  }
  echo " ".$website.$_SERVER['REQUEST_URI']; ?> 
and it doesn't exist. <?php echo $casemessage; ?>  You can click back 
and try again or search for what you're looking for:
  <?php include(TEMPLATEPATH . "/searchform.php"); ?>
</p>

Dynamic Menu Highlighting

The WordPress:Dynamic Menu Highlighting article discusses how to use the conditional tags to enable highlighting of the current page in a menu.

External Ressources

French translation : WordPress:fr:Marqueurs_conditionnels

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