Query posts by Author and/or by Tag

Question

I'm pretty sure I need to do some sort of custom query, but not sure about the best way to go with it.

I have an author page. It needs to display that author's posts. That's fine, I can do that. I need to amend the query so that it displays the author's posts as well as posts tagged to that author's name.

So I imagined the query something like this

query_posts("author=$author_name||tag=$author_name");

I figured that I could set up the query using WP_Query and feeding it the meta_query with the relation OR but that only returned posts by the author and ignored ones that were tagged:

 $args = array( 
   "showposts" => "$show_num_posts", 
   "meta_query" => array( 
   "relation" => "OR", 
        array(
          "author" => "$authID"),
        array(
          "tag" => "$nametag"
        )

   )
 );

 $the_query = new WP_Query($args);

I figure that it's ignoring it because it's found ones by the author and I've specified OR when what I really need is some sort of AND/OR. I've had a look at this example but can't seem to recreate that user's solution to fit my needs. I just keep breaking the whole thing.

global $wpdb;
$args = $wpdb->get_results($wpdb->prepare(
    "
    SELECT $wpdb->posts.*
    FROM $wpdb->posts, $wpdb->postmeta
    WHERE  ($wpdb->posts.author = $authID)
    OR ($wpdb->postmeta.tag = $nametag)
    "
)
);
foreach ( $args as $post ) : setup_postdata($post);

Is there something out there you could point me towards? There has to be an easier way to do this. I'm probably over-complicating it and there's a really simple (probably in-built) way of doing it I've just missed. Searching the codex returned nothing useful though.

Answer 1

Your first query is very strange. You seem to be mixing meta_query parameters with other WP_Query arguments. You can't do that. author is not a valid component of a meta_query, neither is tag. The correct meta_query, if I am interpreting this right, wouldn't even be a meta query. You are dealing with a taxonomy, a tag, so you need a tax_query.

'tax_query' => array(
  array(
    'taxonomy' => 'post_tag',
    'field' => 'slug',
    'terms' => $nametag
  )
)

Unfortunately, if you build a complete query with an author, you get an AND between the tax query and the author, and you need an OR.

$query = new WP_Query( 
  array( 
    'author' => 1, 
    'tax_query' => array(
      array(
        'taxonomy' => 'post_tag',
        'field' => 'slug',
        'terms' => 'depo'
      )
    )
  )
);

That will give you the following query.

SELECT SQL_CALC_FOUND_ROWS wp_posts.ID 
FROM wp_posts 
INNER JOIN wp_term_relationships ON (wp_posts.ID = wp_term_relationships.object_id) 
WHERE 1=1 
AND ( wp_term_relationships.term_taxonomy_id IN (57) ) 
AND (wp_posts.post_author = 1) 
AND wp_posts.post_type = 'post' 
AND (wp_posts.post_status = 'publish') 
GROUP BY wp_posts.ID 
ORDER BY wp_posts.post_date DESC LIMIT 0, 5

That is not your data, but it is illustrative.

The AND right here-- AND (wp_posts.post_author = 1)-- is a problem. You need that to be an OR. In fact you need it in parenthesis too ...

SELECT SQL_CALC_FOUND_ROWS wp_posts.ID 
FROM wp_posts 
INNER JOIN wp_term_relationships ON (wp_posts.ID = wp_term_relationships.object_id) 
WHERE 1=1 
AND ( 
  (wp_term_relationships.term_taxonomy_id IN (57)) 
  OR (wp_posts.post_author = 1) 
)
AND wp_posts.post_type = 'post' 
AND (wp_posts.post_status = 'publish') 
GROUP BY wp_posts.ID 
ORDER BY wp_posts.post_date DESC LIMIT 0, 5

You would have to create a filter for posts_where to correct that, but since you are already writing your own SQL I will leave that alone. I think you can make things work using the query above as a reference.