Relation fallback if no category has been selected I have a filter with a few different parameters that get pulled in and I was wondering if there was a relatedTo wildcard that I could use.

Here's the relevant code: 

{% set function = craft.app.request.getParam("function") %}

{% set functionSection = 'craft.categories.group('businessFunction')'  %}

{% if function | length %}
    {% set functionSection = craft.categories.group('businessFunction').slug( function|split(',') ) %}
{% endif %}


{% set posts = craft.entries({
          section: category,
          relatedTo: [
              'and',
              { element: functionSection } 
          ]
}) %}


The problem is if an entry doesn't have any Business Function selected then it's not related. I could have a conditional that ignores the relationship but there's multiple relations in the real code - it'd be easier if I could set functionSelect equal "all" or something similar.
I had to use a bunch of conditionals to accomplish this - it's not ideal but here's what I came up with

{% set category = craft.app.request.getParam("category") %}
{% set function = craft.app.request.getParam("function") %}
{% set industry = craft.app.request.getParam("industries") %}

{% if not category | length %}
        {% set category = "blog,caseStudies,videos,webinar,whitePapers" %}
{% endif %}

{% set category = category | split(',') %}


{% set posts = craft.entries({
    section: category,
    orderBy: "postDate desc"
}) %}

  {% if function | length %}
    {% set functionSection = craft.categories.group('businessFunction').slug( function|split(',') ) %}
    {% set posts = posts.relatedTo(functionSection) %}
  {% endif %}

  {% if industry | length %}
    {% set industrySection = craft.categories.group('industry').slug( industry|split(',') ) %}
    {% set posts = posts.relatedTo(industrySection) %}
  {% endif %}