Can’t get post id on page that is a custom post type archive

I have a custom post type archive archive-projects.php that I am using as a page template because I have some custom fields that I want to display. I am trying to get the post id of this page but either get null or the id of the first post in the archive depending on what I try. I have tried putting my code above the loop on my page but without any luck.

Apologies if this is a duplicate but I have tried searching many tutorials on this and still don’t have an answer with my specific scenario of using a page template with a custom post type archive.

I have tried this code and it works but I am still stumped as to why none of the other methods seem to work. I’m reluctant to keep this as a solution because if the user changes the page slug this won’t work anymore:

$my_page_id = get_id_by_slug('projects');

function get_id_by_slug($page_slug) {
$page = get_page_by_path($page_slug);
if ($page) {
    return $page->ID;
} else {
    return null;
}
}

I have tried the following without success (above my custom loop in my template):

get_queried_object_id(); // returns nothing
$page_id = $wp_query->get_queried_object_id(); // returns 0

global $post; // I've tried including this and removing with same effect
$post = $wp_query->post;
$post_id = $post->ID; // returns the id of the first post in my archive

Any ideas on what I am doing wrong or the right way to get the actual id of my projects page?

UPDATE My custom post type had has_archive set to true. I tried creating a custom template but due to WordPress hierarchy it was looking for an archive page. I solved my issue by setting has_archive to false and creating a custom template called page-template-projects.php. I was then able to setup a page called Projects and use my custom template, while being able to correctly get an ID for the page.

EDIT

I get the idea that I might have misread your question

Just a few notes here

• If archive-projects.php is a page template, rename it. You should not use archive as a prefix for a page template, or for that matter any other reserved template name. Page templates should be named page-{$name}.php or any other name with prefixes used by the template hierarchy. This is confusing to WordPress and messes with the template hierarchy

• If this is a page template, you should get the ID with get_queried_object_id(); or display it with echo get_queried_object_id();

• If this is a true archive page, you won’t get an ID

ORIGINAL ANSWER

Archive pages, whether post type archive pages, category archives, date archives etc, search pages, single pages and the homepage are pseudo pages, in other words, fake pages. They don’t have ID’s as they do not exist because they are not created pages which is saved in the db

These pages “inherits” the ID of the specific post or archive they display, although they still don’t have an ID themselves, accept the homepage, date archives, search pages and post type archive pages

So, in short, your custom post archive page will not have an ID.

PROOF OF CONCEPT

You can do a var_dump($wp_query) on your archive page, you will see that only real pages have ID’s

?><pre><?php var_dump($wp_query); ?></pre><?php