Custom Shortcode w/ Custom $tax_query Attribute - php

Question

I'm trying to create a custom shortcode in Wordpress that will let me place an attribute to specify a category and query within a custom post type called "case_studies". The taxonomy itself is called "case_study_categories" and I've set the default to be "furniture-interior", as you can see.
What I need is for the shortcode to look something like this:
[get_project_gallery order="ASC" tax_query="flooring"]
Ideally, the shortcode attribute I've placed would override the default of "furniture-interior" and instead use "flooring" to display the appropriate posts. Actually, I would think I don't even really need a default defined at all (so it would just get all the case_studies posts if no attribute is specified) but I can't get that to work either.
BTW, the attribute for order works exactly the way I would want - it overrides the defined default. I just can't figure out how to get this done with the $tax_query.
Any help on this would be very much appreciated. Thanks in advance all!
Here's my code:
function project_gallery_function($atts, $content = null) {
extract(shortcode_atts(array(
'order' => 'DESC',
'orderby' => 'date',
'tax_query' => array(
array(
'taxonomy' => 'case_study_categories',
'field' => 'slug',
'terms' => 'furniture-interior'
)
)
), $atts));
$args = array(
'post_type' => 'case_studies',
'post_status' => 'publish',
'posts_per_page' => '4',
'order' => $order,
'orderby' => $orderby,
'tax_query' => array($tax_query)
);
// The Query
$the_query = new WP_Query( $args );
// The Loop
if ( $the_query->have_posts() ) {
echo '<aside class="grid-gallery four-col grid-gap-4">';
while ( $the_query->have_posts() ) {
$the_query->the_post();
$gallery_thumb = get_the_post_thumbnail_url( $page->ID, 'thumbnail' );
echo '<img src="'. $gallery_thumb .'" alt="" />';
}
echo '</aside>';
}
/* Restore original Post Data */
wp_reset_postdata();
}
add_shortcode( 'get_project_gallery', 'project_gallery_function' );

Answer 1

You shouldn't be worrying about the whole entire tax_query unless you plan on actually redoing the whole tax_query. You should consider changing it to just using $terms instead, since that's the only part you're replacing with the shortcode (you don't need to rebuild the whole array).
Secondly, make sure your code is normalized with your spacing and indentation - future you appreciates the forethought!
Lastly, you could consider passing even more variables to the array to make it a bit more extensible - $posts_per_page, $taxonomy etc.
function project_gallery_function( $atts, $content = null ){
extract( shortcode_atts( array(
'terms' => 'furniture-interior',
'field' => 'slug',
'order' => 'DESC',
'orderby' => 'date',
'taxonomy' => 'case_study_categories',
'post_type' => 'case_studies',
'posts_per_page' => 4,
), $atts ) );
$tax_query = array(
array(
'taxonomy' => $taxonomy,
'field' => $field,
'terms' => explode(',', preg_replace('/\s+/', '', $terms)), // Force to array, allowing comma sep values
)
);
$args = array(
'post_type' => $post_type,
'post_status' => 'publish',
'posts_per_page' => $posts_per_page,
'order' => $order,
'orderby' => $orderby,
'tax_query' => array( $tax_query )
);
// The Query
$the_query = new WP_Query( $args );
// The Loop
if( $the_query->have_posts() ){
echo '<aside class="grid-gallery four-col grid-gap-4">';
while( $the_query->have_posts() ){
$the_query->the_post();
if( $gallery_thumb = get_the_post_thumbnail_url( $page->ID, 'thumbnail' ) ){
printf( '<img src="%s" alt="" />', get_the_permalink(), $gallery_thumb );
}
}
echo '</aside>';
}
/* Restore original Post Data */
wp_reset_postdata();
}
add_shortcode( 'get_project_gallery', 'project_gallery_function' );
A few other notes, get_the_post_thumbnail_url() returns a falsey value if it doesn't exist, so you should wrap that in an if statement incase the image can't be found for some reason (corrupted, removed, forgot to add, etc). Also you have a $page->ID variable in get_the_post_thumbnail_url() - but don't seem to have a global $page in the function? Make sure that's the variable you want to use there.
Using code like what I've provided will let you do what you want, [get_project_gallery order="ASC" terms="flooring"], or even add multiple [get_project_gallery order="ASC" terms="flooring,something-else,a-third-thing"] - just match up the shortcode attributes with the parameter you want to override: [get_project_gallery order="ASC" terms="flooring,something-else,a-third-thing" posts_per_page="15"]