You’ll need to have a look at the posts_clauses filter. There’re more specialised filters as well like posts_where, but you’ll finally end up using the all in one filter.
Then you can inspect the outcome using the 'posts_selection' hook right below that, or the posts_results filter a bit later on.
There’s as well the posts_search filter as searches use a bit different SQL strings.
The final result can be inspected using $wpdb->last_query, or in case of an error using $wpdb->last_error.
If a user is logged in and should be able to search all the blogs he’s registered to, get_blogs_of_user() might be an option. Retrieving a general list of all blogs isn’t hard as well.
Related Posts:
- Creating search form for custom database table
- Search through custom post type and custom fields takes 5 minutes
- Customise search form in the Widget
- Comment filtering (search)
- Combine multiple words in custom meta search query
- Custom search page and search by title, content and tag
- Search a post using the date it was posted
- Setting custom search engine indexing for a “dynamic WordPress page” with htaccess
- Custom URL going to 404
- Search result page redirect ex.com/?s=searchterms to ex.com/searchterms
- Hi, I wanted to make custom search with multiple fields
- Steps for custom data retrieval
- Custom search to display results within same page
- Search widget will search everything in the site, how to limit to only search gallery name
- How to hook up search results page to a back-end page?
- Admin search post meta
- Add a searchbox to the body of a page
- Custom Search on Custom Page while preserving the main search function
- Custom Loop Query For Search Page
- Search URL parameters query [duplicate]
- Applying WP-cli Search & Replace to Static SQL Dump File
- How to create custom search page
- Custom Same Page Search
- How to Add Additional Search Button?
- How to Clear Empty Search values?
- WP Search Form Query: Add Author’s posts into search query
- WordPress search on a custom table
- Adding overlay search to wordpress using add action/filter
- Allow WP users to sort search result on a videos site
- WP_User_Query Search Multiple Keywords from a Multi-Select Field?
- Custom dropdown search form that allows users to select option B based from Option 1
- Custom search results
- WordPress custom search – pagination
- Creating a search with tag variable also added for more detailed results
- What shortcode should I use for
- Two searchforms with different categories/posts per page
- Search a meta field for a value in all posts
- Custom search by several options send on form not works
- Search results load individual post in slide out div
- Custom Search Results Page
- Create a custom search for Estate Agency WordPress site
- How can I make a search term redirect to a page
- Sort Search Results in Order of/by Character @ count (9) of post(s) title. (Ocean-WP theme)
- Show total sales for each products on search results page Woocommerce
- Custom Search on media files PDF images pages posts
- What Is The Use Of map_meta_cap Filter?
- How to *remove* a parent theme page template from a child theme?
- How to disable page delete
- Need logged in users returing to site redirected to a separate page
- Widgets vs. Theme Mods
- Adding an email column to a Custom Post Types Admin Screen?
- Print shortcode in custom action hook not where the shortcode is entered
- simple expandable vertical menu, java script problem
- sanitize attachment filename
- Best way to integrate an existing PHP application into WordPress
- wp_query ‘s’ parameter does not work with custom post type
- How do I add a new template to my site
- Adding code to child’s theme css and php cannot override certain elements
- Woocommerce custom search
- How can I use a Tiny MCE editor in my custom Gutenberg block?
- Changing settings of WooCommerce
- How can I stop access of unregistered user in wp-content/uploads directory without using .htaccess file?
- wp_customize set_transient except during preview
- How do you add a table to a site?
- how to make a custom field readonly or disabled by user role?
- How to make wordpress use a non-wordpress users table?
- WooCommerce custom billing fields on email address
- Is there a straight-forward way to provide a meta description tag via Yoast SEO, programmatically, without relying on the admin panel?
- Restrict content access to logged in users
- Make tag archive display post are ordered by post format
- Custom Form not generating URL
- How to move meta information in TwentyTwelve’s single post template?
- WordPress Command Question
- getting a 404 page for all pages except home. possibly permalinks
- How do I create a Custom Post Box that Connects Different Posts Together
- Pull Latest Forum Posts within WordPress
- saving the widgets position after drag and drop
- Google calendar in wordpress showing events
- Custom menu not showing even though it shows as being registered?
- Open login logo URL in new tab
- Multisite with subdirectories, and a WordPress installation in a custom folder
- Display all subterms of a custom taxonomy filtered by parent terms
- Delete a column in edit.php generated with a plugin
- Migrating my site to a new domain does not keep any changes made in customizer
- how to add custom html and css to wordpress
- How to use the same custom page template to iframe multiple urls with entry of new url entered from backend
- Unhook a function within a class in the child theme
- Where to put coding a validation script for store? [duplicate]
- How to define active widget with js in a customizer
- where can i find the login page in wordpress and add my header to it
- Class .current-menu-item in custom menu Walker
- Add several fields from different tables to post, fields per post are in same row of table
- Custom folder structure and problem with 3rd party services
- How to strip thumb from widget
- Issue with WordPress native theme customizer function and jquery ui tabs
- add custom css on all page exept of one
- Typing and seeing math equations on WordPress site
- Upgrade to 3.1.1 Fails
- Very Simple Geo targeting
- Consolidate ‘add-to-cart’ buttons into one ‘add-all-to-cart’ button