Wordpress Administration menu pointed to the theme file - php

Question

I want to add custom menu and sub-menu to Wordpress admin area. I read some info about it in Codex and I added menus using the function below, which I placed in my theme's functions.php
add_action( 'admin_menu', 'restaurant_menu' );
function restaurant_menu() {
add_menu_page( 'Restaurants Admin Page', 'Restaurants', 'manage_options', get_template_directory() . '/inc/restaurants.php', 'restaurants_admin_page', 'dashicons-format-aside', 6 );
The menu is added to the Wordpress admin sidebar, but I when I'm going that page it goes to the next link:
http://site.ge/wp-admin/admin.php?page=home%2Fbmtbow%2Fpublic_html%2Ftesting%2Fwp-content%2Fthemes%2Fmytheme%2Finc%2Frestaurants.php
but there is no any content, like it is not pointed to the right PHP file.
Am I doing something wrong? and could you help me to solve this problem?

Answer 1

The add_menu_page function doesn't seem to accept a php file as an argument for content. But it does take a function name. You can call your php file with the content in a function, then pass that function as an argument to add_menu_page. (As a side point, you might have the order of your arguments mixed up. The slug is supposed to be 4th, not 5th.) More information about add_menu_page() and it's arguments can be found here.
Try this:
add_action( 'admin_menu', 'restaurant_menu' );
function restaurant_menu() {
add_menu_page( 'Restaurants Admin Page', 'Restaurants', 'manage_options', 'restaurants_admin_page', 'restaurant_admin_page_contents', 'dashicons-format-aside', 6 );
}
function restaurant_admin_page_contents(){
include get_template_directory() . '/inc/restaurants.php';
}