Add query string variables to all hyperlinks URL matching a specified domain

Question

This is my case. Supposing in my plugin dB table I have the following stored field name and values:

argument_1= 'test'
argument_2= 'test2'

And I want to add a new string query string variables to all links going out to www.example.com such that it will look like this:

If homepage is accessed:

www.example.com/?argument_1=test&argument_2=test2

Or any page like this:

www.example.com/anotherpage/?argument_1=test&argument_2=test2

What Wordpress hooks, actions and filters would I be using to retrieve the arguments and values in the database and append it to a hyperlink URL if it matched the domain, e.g. example.com ?

I am thinking of using add query arg but I'm confused a bit on how this function relates to this application. Any tips and advices are highly appreciated..Thanks.

Answer 1

Sorry I read your question wrong. You probably want to use WP_Rewrite and do something like:

add_filter( 'rewrite_rules_array','my_insert_rewrite_rules' );
add_filter( 'query_vars','my_insert_query_vars' );
add_action( 'wp_loaded','my_flush_rules' );

// flush_rules() if our rules are not yet included
function my_flush_rules(){
    $rules = get_option( 'rewrite_rules' );

    if ( ! isset( $rules['(argument_1=test&argument_2=test2)$'] ) ) {
        global $wp_rewrite;
        $wp_rewrite->flush_rules();
    }
}

// Adding a new rule
function my_insert_rewrite_rules( $rules )
{
    $newrules = array();
    $newrules['(argument_1=test&argument_2=test2)$'] = 'index.php?argument_1=$matches[1]&argument_2=$matches[2]';
    return $newrules + $rules;
}

// Adding the id var so that WP recognizes it
function my_insert_query_vars( $vars )
{
    array_push($vars, 'id');
    return $vars;
}

this is untested and mostly stright from the docs but should get you on the right track.