How can I pass WP_Query results to a plugin?

Question

How can I pass the results of a WP_Query call to a plugin? I've tried passing the data via a shortcode attribute, but I get the error "Object of class WP_Query could not be converted to string".

E.g.:

$args = array(
// ...
);

$the_query = WP_Query($args);

echo do_shortcode( [example_custom_plugin query_payload="' . $the_query . '"] );

What are the different (and best advised) ways for a plugin to retrieve variables (which may be objects or arrays of data) that the WP template has set?

In my case, my plugin is instantiated via the shortcode call, hence why I am approaching it from that perspective; I want the plugin to have the results of the WP_Query at instantiation.

Answer 1

I think for shortcodes, which are generally used in the WYSIWYG editor by non-technical users, it's best to keep the parameters simple:

[custom-shortcode color="red" size="medium"]

In other words, shortcodes are designed to provide functionality that an end-user can place somewhere in their content, with the option of supplying a few different customizations.

For obtaining something as a complicated as WP_Query results, I would use:

global $wp_query;

That gives you access to the current query being executed at the moment that your shortcode is run. You can do that in the function that your shortcode would call.

If you need to make an entirely custom query for different data, you can in fact just create a new WP_Query:

function custom_shortcode() {
  $params = [];
  $q = new WP_Query($params);
  // ...
}

So it's best for your plugin to go lookup or get the data versus expecting the data to be passed. That's not always the case, but with what you presented, that seems like the best route.

Answer 2

1. Use global variable
2. Pass just $args and run the same query inside the plugin
3. Serialize results and pass it like you wanted

If I was you, I would prefer 2nd way...