N+1 query on subscribable in admin subscriptions index

[yohanmarshall]

Problem

The admin subscriptions index controller eager loads line_items and user:

@subscriptions = @search.result(distinct: true).
                 includes(:line_items, :user).
                 page(page).per(per_page)

However, the index view iterates over subscription.line_items and accesses line_item.subscribable.name to display the line items column. Since :subscribable is not included in the eager load, this causes an N+1 query — one extra query per subscription row to load the subscribable variant.

For a page with 25 subscriptions, this adds ~25 unnecessary SQL queries. For the export path (which sets per_page to 100,000), this could be significantly worse.

Suggested Fix

Change the includes in the index action from:

includes(:line_items, :user)

to:

includes(line_items: [:subscribable]).includes(:user)

This ensures the subscribable association is eager loaded along with line items, eliminating the N+1.

Environment

• solidus_subscriptions (styrken fork, commit 9318faa)
• File: app/controllers/spree/admin/subscriptions_controller.rb