Wordpress excerpt for specific posts in category

Question

Is there any way to create "more" link for excerpt only for posts in a specific category? For example only posts in "news" category should have a more link. If there's no option for that, maybe posts in specified WP Query?

I am using this code for creating "more" link for excerpts but it works for all posts:

function excerpt_read_more_link( $output ) {
   global $post;
   return $output . '<a href="'. get_permalink( $post->ID ) . '">more</a>';
}
add_filter( 'the_excerpt', 'excerpt_read_more_link' );

toscho thak You for reply. I will check Your solution, but I remeber that I used this code:

if (in_category('news')) { 
function excerpt_read_more_link( $output ) {
   global $post;
   return $output . '<a href="'. get_permalink( $post->ID ) . '">more</a>';

add_filter( 'the_excerpt', 'excerpt_read_more_link' );
}

and this didn't work :-/

Answer 1

Modify the callback and check the post category:

function excerpt_read_more_link( $output ) {
    global $post;

    if ( in_category( 'news', $post ) )
        return $output . '<a href="'. get_permalink( $post->ID ) . '">more</a>';

    return $output;
}

And you should prefix the function name. In its current form it is not safe enough.