Rails 5.0：仅当关联Variations数量大于1时显示缩略图的问题

Hey there! Let's work through why your conditional isn't hiding the variation thumbnails when there's only one variation.

First off, it sounds like the core issue is either your conditional logic is reversed, or you're using the wrong variable/value to check the number of variations. Let's break this down step by step:

1. Fix the Conditional Logic #

You mentioned using <% if v >= 1 %>—but this would show the thumbnails when there's 1 or more variations, which is the opposite of what you want. To hide thumbnails when there's only 1 variation, you need to show them only when there are 2 or more variations.

2. Use the Correct Value to Count Variations #

Make sure you're checking the size of the variations collection, not a single variation object. For example:

• If your partial has access to the parent product object (passed as a local variable or via @product), use product.variations.size (this is efficient if the association is already loaded) or product.variations.count.
• Avoid using a single variation instance (like v) for this check—comparing an object to a number will always evaluate to false, which is why your original code wasn't working.

Example Working Code #

Let's assume you're rendering the partial from products/show.html.erb and passing the product as a local variable:

In products/show.html.erb:

<%= render 'products/var', product: @product %>

In products/_var.html.erb:

<!-- Top Carousel (always shows, even with 1 variation) -->
<div class="variation-carousel">
  <% product.variations.each do |variation| %>
    <!-- Your carousel item markup here -->
  <% end %>
</div>

<!-- Thumbnails (only show if there are 2+ variations) -->
<% if product.variations.size > 1 %>
  <div class="variation-thumbnails">
    <% product.variations.each do |variation| %>
      <!-- Your thumbnail markup here -->
    <% end %>
  </div>
<% end %>

Quick Checks to Troubleshoot Further #

• Double-check that product.variations is returning the correct collection (you can add <%= product.variations.size %> temporarily to print the count on the page and verify).
• Ensure you're passing the product variable correctly to the partial—if you're relying on @product in the partial, confirm it's set in the ProductsController#show action.
• Avoid typos (like misspelling variations as variation—small mistakes break everything!).

内容的提问来源于stack exchange，提问作者Charles Smith