Call to a member function add_rule() on a non-object

Question

I want the page mysite.com/product to be accessed with the URL

mysite.com/product/productname instead of mysite.com/product?name=productname

I am trying to achieve this with the code in the plugins main file:

 add_rewrite_rule('^(product)/([^/]*)/?', 'product?name=$matches[1]','top');

but I am getting the error:

Fatal error: Call to a member function add_rule() on a non-object in /location/wp-includes/rewrite.php on line 21

Any suggestions?

Answer 1

You're calling it too early. Call it on the init hook or later, e.g.:

add_action( 'init', 'add_alexes_rules' );
function add_alexes_rules() {
    add_rewrite_rule('^(product)/([^/]*)/?', 'product?name=$matches[1]','top');
}