How to get the slug using custom query?

Actually, my question is more complex.

Clients can buy a series of recipes. They become gradually available to the buyer.
There is a standard set of recipes, with permalinks .../cpt/recipe-01, -02, -03 etc.
At preset interval the next recipe of the standard set is released to the buyer, by copying the standard recipe to .../cpt/<username>-recipe-01, -02 etc.
This is all working fine.

I want to show an overview of the released recipes to the buyer.
For several reasons I want to do that with the standard set of recipes as starting point, by looking if the permalink .../cpt/<username>-recipe-01, 02 etc. exist.

Therefore I need the following steps:
- determine the slug of the standard recipe (my starting question)
- find out for each recipe if a post for the buyer exists.

Next to my starting question on the slug, I'm having difficulty with
- getting the username
- determining if a post for the buyer exists.

I hope you can help me.

Hi Long,

Thanks for helping me each time a step further.

I find it hard to find all answers myself in WordPress codex and in other sources, although I'm spending hours on it. And yet I have to come to you with what I believe are so basic questions.

I managed to get everything in order. Only part left ìs the condition if a recipe for the buyer exists.
I'll share my code. It results in a critical error on the website.
First I read the standard recipes from 1 package. Then I'll check which recipes of the package exist for the current user, and I show the details. (slug for the recipe for the buyer = <userid>>-recipe-01 etc.)

'''
{% set args = { post_type: 'xtra', include: [ 281, 283, 284, 285, 286, 287, 288, 289, 290, 291, 292 ], order: 'asc' } %}
{% set posts = mb.get_posts( args ) %}
{% set user_ID = mb.get_current_user_id() %}
{% set abs_path = 'https://example.com/xtra/' %}
{% set rel_path = 'xtra/' %}

<div class="xtra_container">
{% for post in posts %}
{% if ( $page = mb.get_page_by_path( {{ rel_path }}{{ user_ID }}-{{ post.post_name }} ) ) %}
{
<div class="xtra_item">
{% set post_link = mb.get_permalink( post.ID ) %}
<h3>{{ post.post_title }} </h3>
[su_row][su_column size="1/2" center="no" class=""]{{ mb.get_the_post_thumbnail( post.ID, 'thumbnail' ) }} [/su_column]
[su_column size="1/2" center="no" class=""][icon name="calendar-check" prefix="fas"] {{ post.post_modified | date( 'F j, Y' ) }} <br> [icon name="comment" prefix="fas"] {{ post.comment_count }} [/su_column][/su_row]
</div>
}
{% endif %}
{% endfor %}
</div>
'''

Can you help me to get this corrected?

I understand what you're doing. But I'm concerned that over time, when both the number of recipes and the number of sales are growing, the performance will become an issue. And with an installed base by then, I'm afraid that getting that solved can become quite a headache.

Therefore I'm looking into a view per set of recipes, I'm sort of hardcoded reading the posts of the set (in this case 11 posts) and subsequently reading/checking which recipes of this set exist for the current user. I.e. getting the post based on the permalink with the username in it.
This way the number of posts to be read is limited to 2x number of recipes in the set.

But my question then is how to read the post by permalink, and how to do the proper coding for the condition if the post exists.

Hope you can help me with that.

Thanks a lot!

Thanks Long, I found the solution through the FB group. Can you close this threat?