Issues when using WordPress rewrite rules then accessing parameter using get_query_var

I’m developing a WP plugin and have a WordPress URL:

(e.g.: http://localhost/testsite1/coder/?id=66),

and have attempted to add a rewrite rule to

http://localhost/testsite1/coder/66/

using the following rule:

function add_mypage_rule(){
    add_rewrite_rule(
        '^coder/([0-9]+)',
        'index.php?id=$matches',
        'top'
    );
}

add_action('init', 'add_mypage_rule');

I have registered a WP Query Var using:

add_filter('query_vars', 'registering_custom_query_var');

function registering_custom_query_var($query_vars){
    $query_vars[] = 'id';
    return $query_vars;
}

but when at URL http://localhost/testsite1/coder/66/, when I run code

echo get_query_var('id');

nothing is displayed

however when at URL http://localhost/testsite1/coder/?id=66 the echo statement will display 66.

What is wrong with my rewrite rule resulting in echo get_query_var('id'); not accessing the parameter and displaying 66?

Answer

1. When you use add_rewrite_rule function, the first argument is the regular expression. Right? When you wrap your regular expression/pattern in parentheses, you’re grouping the expression, which means you could access the captured group in the parentheses like this: id=$matches[1].

• Regular expression ^coder/([0-9]+)
• Access it in the first captured group (since the id is in the first parenthesis), id=$matches[1]

add_action('init', 'add_mypage_rule');

function add_mypage_rule()
{
    add_rewrite_rule(
        '^coder/([0-9]+)',
        'index.php?id=$matches[1]',
        'top'
    );
}

2. After that, refresh the permalinks and rewrite rules by navigating to:
   Settings > Permalinks > Click on the 'Save changes' button at the bottom of the page!

And now it should, theoretically, work, unless there are more details that you have not mentioned in your question!

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