Playing with object construction in Liquid

cross-sell-data.liquid

{% comment %}
  - I have a product with a variant metafield containing associated cross-sell product list
  - Objective is to show cross-sell products associated with the variant
  - Second objective was to use object construction to remove complexity in markup
  - Inside the markup, we need the product reference for data population as well as the variant IDs which needs to show the cross sell card (used by Javascript)
{% endcomment %}

{% liquid
  # First, we make a duplicate-free list of cross-sell products
  assign cross_sell_product_list = ''
  for variant in product.variants
    assign cross_sell_list = variant.metafields.cross_sell.product_list.value
    unless cross_sell_list
      continue
    endunless

    if cross_sell_product_list == blank
      assign cross_sell_product_list = cross_sell_list | uniq
    else
      assign cross_sell_product_list = cross_sell_list | uniq | concat: cross_sell_product_list
    endif
  endfor
  assign cross_sell_product_list = cross_sell_product_list | uniq | reverse

  # Second, we prepare the data (product + associated variant IDs)
  assign cross_sell_data_list = ''
  for cross_sell_product in cross_sell_product_list
    assign cross_sell_data = null
  
    assign variant_id_list = ''
    for variant in product.variants
      assign cross_sell_list = variant.metafields.cross_sell.product_list.value | uniq
      unless cross_sell_list
        continue
      endunless

      if cross_sell_list contains cross_sell_product
        if variant_id_list == blank
          assign variant_id_list = variant.id | uniq
        else
          assign variant_id_list = variant.id | uniq | concat: variant_id_list
        endif
      endif
    endfor

    assign cross_sell_data = null | default: product: cross_sell_product, variant_id_list: variant_id_list
    if cross_sell_data_list == blank
      assign cross_sell_data_list = cross_sell_data | uniq
    else
      assign cross_sell_data_list = cross_sell_data | uniq | concat: cross_sell_data_list
    endif
  endfor

  # Third, we output the data (one simple loop inside markup)
  echo cross_sell_data_list | append: '<br><br>'
  for cross_sell_data in cross_sell_data_list
    echo cross_sell_data.product.title | append: ' - ' | append: cross_sell_data.variant_id_list | append: '<br>'
  endfor
%}

{% # Here is the ouput %}
{% comment %}
  [{"product"=>ProductDrop, "variant_id_list"=>[48838125256992, 48838125224224, 48838122242336]}, {"product"=>ProductDrop, "variant_id_list"=>[48838125256992, 48838125224224, 48838122242336]}, {"product"=>ProductDrop, "variant_id_list"=>[48838125256992]}, {"product"=>ProductDrop, "variant_id_list"=>[48838125224224, 48838122242336]}, {"product"=>ProductDrop, "variant_id_list"=>[48838125224224]}, {"product"=>ProductDrop, "variant_id_list"=>[48838125224224]}, {"product"=>ProductDrop, "variant_id_list"=>[48838125224224]}]
  
  A - [48838125256992, 48838125224224, 48838122242336]
  autumn flower - [48838125256992, 48838125224224, 48838122242336]
  bitter forest - [48838125256992]
  autumn leaf - [48838125224224, 48838122242336]
  chaussure 1 - [48838125224224]
  chaussure 2 - [48838125224224]
  chaussure 3 - [48838125224224]
{% endcomment %}