Get tag slugs from wp post that begin with specific letters then use them in a qp_query

I am trying to create a list of tags that I can use in an array within a wordpress wp_query. I’ve made the tags appear in the template (via echo) so I know I have the output, but I don’t know how to move/use the output from this into the array of the separate wp_query. I normally can find out how to do things via searching but I don’t know what the name is of what I am trying to do. I’m self/internet taught.

$commatext = ",";
$blankcat = "blankcategory";
$tags = wp_get_post_tags( $post->ID );
if ( !empty( $tags ) && !is_wp_error( $tags ) ):
foreach ( $tags as $tag ): if(strpos($tag->slug,'sim-') !== false): echo $tag->slug; echo $commatext; endif; endforeach;
echo $blankcat;
endif;

This outputs:

sim-simname1,sim-simname2,blankcategory

I need to figure out how to put that into a wp_query for the same post:

'tag' =>  array( sim-simname1,sim-simname2,blankcategory )

I do have it working right now but I have to manually type 256 possible tags with sim-… slugs into my wp_query. Automating that would be nice…

Answer

Build a list of your collected sims in a plain array and pass that in an associative array (map) to WP_Query.

Untested but something like …

if ( !empty( $tags ) && !is_wp_error( $tags ) ):
    $simarr = array();
    foreach ( $tags as $tag ):
        if(strpos($tag->slug,'sim-') !== false):
            $simarr[] = $tag->slug;  // push 'sim-' into array
        endif;
    endforeach;
    $simarr[] = "blankcategory";     // add to end of array

    $query = new WP_Query( array('tag' => $simarr) );
endif;

Hope that’s close.

Dave