when use function the_content break

Question

i use the function below to show content under the_content. It works on pages which uses template-test.php. But on other pages the_content stops output.

function beschreibung_kriterien( $content ) {

    if ( is_page_template( 'template-test.php' ) ) {

        $content .= '<h2>Test</h2>';

        return $content;
    }
}
add_filter( 'the_content', 'beschreibung_kriterien', 5 );

Answer 1

Because you only return $content from inside your if - you should always return it:

function beschreibung_kriterien( $content ) {
    if ( is_page_template( 'template-test.php' ) ) {
         $content .= '<h2>Test</h2>';
    }

    return $content;
}

add_filter( 'the_content', 'beschreibung_kriterien', 5 );

This just goes to the show the importance of proper indentation!