the_content │ filter-hook │ WP 0.71

Filters post content after it is retrieved from the database but before it is displayed.

Usage

add_filter( 'the_content', 'filter_function_name_11' );
function filter_function_name_11( $content ) {
	// Filter the content...

	return $content;
}

Parameters

$content(string)

String to filter and return.

Examples

#1 Filter the content of a particular page

This example can create a static page whose content is generated based on something such as a $_GET query variable, for example, a specified author in ?the_author=crank:

add_filter( 'the_content', 'my_the_content_filter' );
function my_the_content_filter( $content ){
	// Do nothing unless this is the debug page.
	if( $GLOBALS['post']->post_name != 'debug' )
		return $content;

	// Perform the required action.
	// The URL is assumed to contain the the_author query variable.
	return "This is the author page for: ". $_GET['the_author'];
}

#2 Post icon

This example adds an image before a post; see is_single(). The image is assumed to be named post_icon.png and located in the theme's images directory. The filter uses the lower priority 20 rather than the usual 10, so it runs after other callbacks.

add_filter( 'the_content', 'my_the_content_filter', 20 );
function my_the_content_filter( $content ){
	if ( is_single() )
		// Add an image to the beginning of every page.
		$content = sprintf(
			'<img class="post-icon" src="%s/images/post_icon.png" alt="Post icon" title=""/>%s',
			get_bloginfo( 'stylesheet_directory' ),
			$content
		);

	// Return the content.
	return $content;
}

#3 Featured image at the beginning

This example adds a post's featured image before its content. The featured image is selected while editing the post, and the feature must be enabled; see add_theme_support(). It is added only to posts of the post post type:

add_filter( 'the_content', 'featured_image_before_content' );
function featured_image_before_content( $content ) {
	if ( is_singular('post') && has_post_thumbnail()) {
		$thumbnail = get_the_post_thumbnail();

		$content = $thumbnail . $content;
	}

	return $content;
}

#4 Advertisements in posts after a particular number of paragraphs

This example filters content and adds advertisement code after a specified number of paragraphs.

# Insert advertisements after a particular number of paragraphs.
add_filter( 'the_content', 'wpse_ad_content' );

function wpse_ad_content( $content ) {

	if( ! is_single() ){
		return $content;
	}

	// Paragraph number after which to insert the data.
	// Preferably supplied through a meta field.
	$paragraphAfter = 5;
	$return_content = '';
	$ads_block = '<a href="#">ADS</a>';
	$content = explode( "</p>", $content );

	foreach( $content as $i => $value ){

		$return_content .= $value . "</p>";

		if( $i === 0 ){
			$return_content .= $ads_block;
		}

		if( $i === $paragraphAfter ){
			$return_content .= $ads_block;
		}

		if( $i === array_key_last( $content ) ){
			$return_content .= $ads_block;
		}
	}

	return $return_content;
}

#5 Demonstration

To demonstrate the filter, append " The End!" to every post's content:

add_filter('the_content', 'the_end');
function the_end( $text ){
	return $text . ' The End!';
}