Show a collection based summary using data from the Shopify Product Reviews App.

collection-ratings.liquid

{% comment %}

  Usage: 
  {% include 'collection-ratings' %}
  {% include 'collection-ratings' collectionHandle:'some-handle' useAll:true %}

{% endcomment %}
{% if collectionHandle == blank %}{% assign collectionHandle=collection.handle %}{% endif %}
{% if collections[collectionHandle].products.size > 0 %}
  
  {% comment %} Setup the basic vars {% endcomment %}
  {% assign collection = collections[collectionHandle] %}
  {% assign reviewAverage = 0 %}
  {% assign reviewVotes = 0 %}
  {% assign reviewedProducts = 0 %}
  {% assign maxReview = 5 %}

  {% comment %} The two vars below is sections of the metafield we need to find {% endcomment %}
  {% assign splitMarkerAverage = 'itemprop="average" content="' %}
  {% assign splitMarkerVotes = 'itemprop="votes" content="' %}

  {% comment %} Loop over the product {% endcomment %}
  {% for product in collection.products limit:50 %}

    {% comment %} Grab the review metafield {% endcomment %}
    {% assign productReviewMetafield = product.metafields.spr.reviews %}

    {% comment %} Some quick checks to see if the metafield exists, and has what we need. {% endcomment %}
    {% if productReviewMetafield == blank %}{% continue %}{% endif %}
    {% unless productReviewMetafield contains splitMarkerAverage and productReviewMetafield contains splitMarkerVotes %}{% continue %}{% endunless %}

    {% comment %} Get the values from the metafield (hopefully)! {% endcomment %}
    {% assign productAverage = productReviewMetafield | split:splitMarkerAverage | last | split:'"' | first | abs %}
    {% assign productVotes = productReviewMetafield | split:splitMarkerVotes | last | split:'"' | first  | abs %}
    
    {% comment %} Update our values {% endcomment %}
    {% assign reviewAverage = reviewAverage | plus:productAverage  %}
    {% assign reviewVotes = reviewVotes | plus:productVotes %}
    {% assign reviewedProducts = reviewedProducts | plus:1 %}
    
  {% endfor %}

  {% comment %} Set the average based on product count {% endcomment %}
  {% assign reviewedAllAverage = reviewAverage | divided_by:paginate.items | round: 1 %}

  {% comment %} Set the average based on products with a review {% endcomment %}  
  {% assign reviewedOnlyAverage = reviewAverage | divided_by:reviewedProducts | round: 1 %}

  <span class="collection-review-summary">
    {% if useAll != blank and useAll != false %}
      {{ collection.title }} Rating: {{ reviewedAllAverage }} out of {{ maxReview }} based on {{ reviewVotes }} {{ reviewVotes | pluralize: 'review', 'reviews' }}.
    {% else %}
      {{ collection.title }} Rating: {{ reviewedOnlyAverage }} out of {{ maxReview }} based on {{ reviewVotes }} {{ reviewVotes | pluralize: 'review', 'reviews' }}.
    {% endif %}
  </span>

{% endif %}

collection.ratings-json.liquid

{% layout none %}{% capture WHITESPACE %}

{% comment %}

  This is intended to be used as an alternate collection template.
  Usage:

  1. Add new collection template, adding this code.
  2. View the collection https://yourstore.com/collections/foo?view=ratings-json
  3. Read the output with JavaScript and add to your page as needed.


{% endcomment %}

{% comment %} Setup the basic vars {% endcomment %}
{% assign reviewAverage = 0 %}
{% assign totalReviews = 0 %}
{% assign reviewedProducts = 0 %}

{% comment %} Do not edit the two lines below unless you know what they do {% endcomment %}
{% assign splitMarkerAverage = 'itemprop="average" content="' %}
{% assign splitMarkerVotes = 'itemprop="votes" content="' %}

{% comment %} Add the usual pagination tags {% endcomment %}
{% paginate collection.products by 1000 %}
{% for product in collection.products %}

  {% assign productReviewMetafield = product.metafields.spr.reviews %}

  {% comment %} Some quick checks to see if the metafield exists, and has what we need. {% endcomment %}
  {% if productReviewMetafield == blank %}{% continue %}{% endif %}
  {% unless productReviewMetafield contains splitMarkerAverage and productReviewMetafield contains splitMarkerVotes %}{% continue %}{% endunless %}

  {% comment %} Get the values from the metafield (hopefully)! {% endcomment %}
  {% assign productAverage = productReviewMetafield | split:splitMarkerAverage | last | split:'"' | first | abs %}
  {% assign productVotes = productReviewMetafield | split:splitMarkerVotes | last | split:'"' | first  | abs %}

  {% comment %} Update our values {% endcomment %}
  {% assign reviewAverage = reviewAverage | plus:productAverage  %}
  {% assign totalReviews = totalReviews | plus:productVotes %}
  {% assign reviewedProducts = reviewedProducts | plus:1 %}

{% endfor %}

{% comment %} The review average var is the combined amount for all products. Let's get the average and round that amount. {% endcomment %}
{% assign productsSearched = paginate.items %}
{% assign reviewAverage = reviewAverage | divided_by:productsSearched | round: 1 %}

{% endpaginate %}
{% endcapture %}{% if reviewAverage > 0 and totalReviews > 0 %}
{
  "reviews":{
    "totalReviews":{{ totalReviews | json }},
    "reviewAverage": {{ reviewAverage | json }},
    "reviewedProducts":{{ reviewedProducts | json }},
    "productsSearched":{{ productsSearched | json }}
  }
}{% endif %}

shopify-collection-ratings-summary.md

#Show a collection based summary using data from the Shopify Product Reviews App. This relates to the blog post on the freakdesign blog.

There's two files other files in this gist:

• A snippet intended for small collections, ready to add into the theme
• An alternate collection template

For more info: http://freakdesign.com.au/blogs/news/150719175-show-shopify-product-reviews-as-an-average-for-the-entire-collection

Exactly what I was looking for - thank you very much!