Shopify: Show all numbers in pagination, retaining query parameters. Inspired by: https://gist.github.com/kyleaparker/7588995

shopify_pagination.liquid

{% for part in (1..paginate.pages) %}
  {% if forloop.index == 1 %}
    {% if paginate.next.is_link %}
      {%- assign next_page = current_page | plus: 1 -%}
      {%- assign page_query_param_old = 'page=' | append: next_page -%}
      {%- assign page_url_template = paginate.next.url -%}
    {% elsif paginate.previous.is_link %}
      {%- assign previous_page = current_page | minus: 1 -%}
      {%- assign page_query_param_old = 'page=' | append: previous_page -%}
      {%- assign page_url_template = paginate.previous.url -%}
    {% else %}
      {%- assign page_query_param_old = 'page=page' -%}
      {%- assign page_url_template = collection.url | append: '?page=page' -%}
    {% endif %}
  {% endif %}
  {%- assign page_query_param_new = 'page=' | append: forloop.index -%}
  {%- assign page_url = page_url_template | replace: page_query_param_old, page_query_param_new -%}

  <li class="page {% if paginate.current_page == part %}current{% endif %}">
    <a class="page__number" href="{{ page_url }}">{{ forloop.index }}</a>
  </li>
{% endfor %}

Thank you for this code. It really helped.