Display author box on just certain category posts?

Question

I'm using this code to display a author box after my blog posts. The issue that I'm having is that it is showing up on all custom post types as well which I don't want. What I need is for it to show up on posts that are in the category of 'blog'. Anyone have any suggestions on what I need to do to accomplish this?

Thanks in advance!

// creates the author bio after posts
function get_author_bio ($content=''){
global $post;

$post_author_name=get_the_author_meta("display_name");
$post_author_description=get_the_author_meta("description");      
$html="<div class='clearfix' id='about_author'>\n";
$html.="<img width='80' height='80' class='avatar' src='http://www.gravatar.com/avatar.php?gravatar_id=".md5(get_the_author_email()). "&default=".urlencode($GLOBALS['defaultgravatar'])."&size=80&r=PG' alt='PG'/>\n";
$html.="<div class='author_text'>\n";
$html.="<h4>Author: <span>".$post_author_name."</span></h4>\n";
$html.= $post_author_description."\n";
$html.="</div>\n";
$html.="<div class='clear'></div>\n";
$content .= $html;

return $content;
}

add_filter('the_content', 'get_author_bio');

Answer 1

Use get_post_type() to check the correct post type and in_category( 'blog' ) to check the category:

function get_author_bio ($content=''){

    if ( 'post' !== get_post_type() or ! in_category( 'blog' ) )
        return $content;