product-section-display-block-id.liquid

{%- comment %}

  Product Section Display Block ID
  ------------------------------------------------------------------------------

  Usage:

  {% include 'product-section-display-block-id.liquid',
              product: product,
              blocks: section.blocks
  %}

  In the template, do something like the following.  Be sure to always coerce to a number when doing comparisons since it's not always clear if you're working with strings or numbers in liquid

  {% capture display_block_id %}
    {% include 'product-section-display-block-id', product: product, blocks: section.blocks %}
  {% endcapture %}
  {% assign display_block_id = display_block_id | plus: 0 %}

{% endcomment -%}

{% if product and blocks.size > 0 %}

  {% assign product_block_id    = 0 %}
  {% assign tag_block_id        = 0 %}
  {% assign collection_block_id = 0 %}
  {% assign default_block_id    = 0 %}
  {% assign product_collections_handles = product.collections | map: 'handle' | join: ' $ ' %}

  {% for block in blocks %}
    {% assign block_id = block.id | plus: 0 %} {% comment %} Coerce to a number {% endcomment %}
    {% assign display_product    = all_products[block.settings.product] %}
    {% assign display_collection = collections[block.settings.collection] %}

    {% comment %} The `if _block_ == 0` checks are to ensure that we pull the first matching block {% endcomment %}
    {% if block.settings.product != blank %}
      {% if product.handle == block.settings.product and product_block_id == 0 %}
        {% assign product_block_id = block_id %}      
      {% endif %}
    {% elsif block.settings.tag != blank %}
      {% if product.tags contains block.settings.tag and tag_block_id == 0 %}
        {% assign tag_block_id = block_id %}
      {% endif %}
    {% elsif block.settings.collection != blank %}
      {% if product_collections_handles contains block.settings.collection %}
        {% assign collection_block_id = block_id %}
      {% endif %}
    {% else %}
      {% if default_block_id == 0 %}
        {% assign default_block_id = block_id %}
      {% endif %}    
    {% endif %}

  {% endfor %}

  {% comment %}
    - Output the first block id that matches our logic (decreasing specificity)
    - This logic sucks, but we can't really use a case/when statement here and there's no way to return early from an if/elsif statement in liquid
    - We're only trying to output one block id
  {% endcomment %}

  {% capture display_block_id %}
    {% if product_block_id > 0 %}
      {{ product_block_id }}
    {% else %}
      {% if tag_block_id > 0 %}
        {{ tag_block_id }}
      {% else %}
        {% if collection_block_id > 0 %}
          {{ collection_block_id }}
        {% else %}
          {% if default_block_id > 0 %}
            {{ default_block_id }}
          {% endif %}
        {% endif %}
      {% endif %}          
    {% endif %}
  {% endcapture %}

  {{ display_block_id }}

{% endif  %}