Disable checkout if products do not have same tag Shopify

Question

I have a product (tag contains 'starter-bracelet') in my store that must be sold with another linking product (tag contains 'bracelet-link'). Is there any way to block checkout if only the starter-bracelet product is in there and then allow checkout once the linked product is added?

Thanks in advance

Answer 1

I have managed to sort it, just needed to work out the correct logic.

        {% assign starter_bracelet = false %}
        {% assign nomination_link = false %}
        {% assign allow_checkout = true %}

        {% for item in cart.items %} 
          {% if item.product.tags contains 'starter-bracelet'%}
            {% assign starter_bracelet = true %}
          {% endif %}
          {% if item.product.tags contains 'link' %}
              {% assign nomination_link = true %}
          {% endif %}
        {% endfor %}
        {% if starter_bracelet == true and nomination_link != true %}
              {% assign allow_checkout = false %}
              {% render 'nomination-checkout-message' %}
        {% endif %}