Searching through multiple Wordpress site post

Question

We have multiple Worpdress blog sites (20+ sites) with each of them on their own domain and have now started creating a main website were we would like to add a search function / bar, where a visitor can do a search on the main site and it will then return a result of all the post that matches their search. From there on if they click on a post that was listed it will take them to the post on the relevant blog site, so no need to have a 2nd page for the post on the main site.

My thought so far was to use the WordPress Rest API and "wp_remote_get" function to accomplish this but there is some concerns regarding the speed of the search when the number of blog sites increase and security.

Moving all the blogs to a single site or multi site setup is not a option because I would like the option the be able to move the sites to other host if needed.

So I was wondering if anyone maybe knows of a better way do approach project.

Answer 1

Firstly, I'd try to handle a query on backend. Then obtain search results for each blog and finally Echo them to the page content.

Also you need to find a php file (in your active theme) that shows search results. Usually it is something like search.php or content-search.php.

<?php
/**
 * The template for displaying search results pages
 *
...

$query=get_search_query();

$args = array( 's' => $query );

$the_query = new WP_Query( $args );

$posts = $the_query->posts;

foreach($posts as $post) {
    // Echo some info
    // echo $post->post_name . '<br>';
}

This will show results for the current blog. So, you need to switch to every blog and get its posts for the same query ($query=get_search_query()).

https://developer.wordpress.org/reference/functions/get_sites/

https://developer.wordpress.org/reference/functions/switch_to_blog/

$sites = get_sites();
    foreach ( $sites as $site ) {
        switch_to_blog( $site->blog_id );

                $query=get_search_query();
    
                $args = array( 's' => $query );
    
                $the_query = new WP_Query( $args );
    
                $posts = $the_query->posts;
    
                foreach($posts as $post) {
                   // Echo some info
                  // echo $post->post_name . '<br>';
                 }
        restore_current_blog();
    }

UPD: yeap, this works for wp multysite only. Here is the option for separate sites

When you search something in your site, basically, you make a GET request:

https://your-wp-site.com/?s=QUERY_STRING&submit=Search

So, you can make Ajax GET requests ?s=QUERY_STRING&submit=Search for each domain, using js. Then parse results and insert them to the content, also using js.

function loadDoc(url) {
  var xhttp = new XMLHttpRequest();
  xhttp.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {

     //parsing this.responseText

    var main_content = document.getElementById("main"); /*supposing your main content tag has id='main'*/

    main_content.appendChild(PARSED_ELEMENT_WITH_RESULTS);

    }
  };
  xhttp.open("GET", url, true);
  xhttp.send();
}



var query = window.location.href.split('/')[3]; /*getting query string ?s=QUERY_STRING&submit=Search */

loadDoc("https://site1.com/"+query );

loadDoc("https://site2.com/"+query );

loadDoc("https://site3.com/"+query );

...

Finally, add this javascript file to the search page.