Use specific category for every author on author page

Question

The authorpage is begin generated, and every post that an author has made will be shown. However I only want to show posts from a specific category (id=1).

So basically, when you visit

mysite.com/author/John

you should see only posts from John, with category ID=1 and on

mysite.com/author/Bob

you should see only posts from Bob, with category ID=1.

When I do this in archive.php:

/* Start the Loop */ 
query_posts('cat=1');                               
while (have_posts()) {
    the_post();
    get_template_part('content', get_post_format());
}

Unfortunately, when I do this, every post in category 1, will be shown on every author page...(You see Bobs and Johns posts on Johns author-page).

I have also tried this, but same results as above:

$curauth = get_userdata($row->ID);
$user_link = get_author_posts_url($curauth->ID);
$posts = get_posts(array(
     'author' => $curauth->ID,
     'cat' => 1
     'posts_per_page' => -1,
    )
);
$post_count = count($posts);

I have 2 questions.

1. Should I code in archive.php or should I make the adjustments in author.php (not available in the theme).

2. More importantly, how do I show catID=1 for every author ?

PS: View full code here

Answer 1

I have written a quite extensive post on a similar subject that you can read here. Also take your time and read all linked posts.

In there I have explained why you should not be using query_posts and why you should not use custom queries in place of the main query

A few things here:

• Remember to create a child theme, do not make changes to a theme that you have not written. You will loose all your work if you update that theme

• It is real easy to create your own author archive page. Simply make a copy of your index.php and rename it author.php. It is that easy

• Use pre_get_posts to make changes to your author page. Do not make changes directly through a custom query on your author page. You can use the following in your functions.php

  function wpse166864_include_category( $query ) {
      if ( !is_admin() && $query->is_author() && $query->is_main_query() ) {
         $query->set( 'cat', '1' );
      }
  }
  add_action( 'pre_get_posts', 'wpse166864_include_category' );