how to stop a .md file from being generating an html file in jekyll

Question

i'm kinda new to jekyll. in my project i have few .md files(each file relate to a portfolio project). some of those need to generate separate .html files when built(which jekyll already does). but i want to exclude some files from being creating separate html files.

But the important thing is, even though i want to exclude those .md files from creating seperate .html files i still want to use the front matter of those files.(as i'm using a for loop to generate a list of all the portfolio projects)

i tryied adding those .md files to the _config.yml under exclude. but that will stop parsing the front matter as well.

is there a way in jekyll which i can achieve this.

edit:

project1.md

---
title: project1
display: true
category: portfolioProjects
---

This is a test content

project2.md

---
title: project2
display: false
category: portfolioProjects
---

if i have 2 files like above, i would like to render project1.md as a .html file(as it has a content to be shown in a page) and not generate project2.md as a separate file.But i still want to access front matters of both files to make a list of projects like,

{% for project in site.projects %}
{{project.title}}
{% endfor %} 

I believe i can use 2 types of collections and set output to true for one type of collection and false to other type of collection. But I'm wondering whether there is a much cleaner way like conditionally setting output to true or false depending on a front matter value. eg. output : (display)? true : false