List entries related to several categories

Question

This is the code used to display entries related to categories.

The issue: if an entry belongs to 2 categories, it displays all the categories to which it belongs on the page.

I need Craft to display only the category and entries the (lastSeg) of the slug (selected from a nav).

Can't find where to start?

{% set entries = craft.entries.section('contenuCompositions').relatedTo(category).order('dateYear','comp_opus','title').limit(0) %}
{% for category in craft.categories.group('compositions').relatedTo(entries).level(2).slug(lastSeg) %}
<div class="container">
<div class="row">
    <div class="col-md-12">
        <h1>{{ category }}</h1>
    </div>
</div>
{% for row in entries.relatedTo(category)|batch(3) %}
<div class="row">
    {% for entry in row %}
      <div class="col-md-4">
        <p>{{ entry.title }}
      </div>
    {% endfor %}
</div>
</div>
{% endfor %}
</div>

Answer 1

Not sure if this is still what you are after (I removed a lot of parameters), but basically this gets the one (!) category with the unique (!) slug you request from the URL and then lists the entries related to it:

{% set categorySlug = craft.request.getLastSegment() %}
{% set category = craft.categories.group('compositions').slug(categorySlug).first() %}

<h1>{{ category.title }}</h1>

{% set entries = craft.entries.section('contenuCompositions').relatedTo(category) %}

{% for entry in entries %}
    {{ entry.title }}
{% endfor %}