Spree Promotions

A promotion is “if X is true about the cart, do Y.” Spree breaks that into:

Promotion           — the campaign (name, dates, code, usage limits)
  ├── PromotionRule × n        — eligibility checks: "if X is true"
  ├── PromotionAction × n      — what to do: "create a discount", "free shipping"
  │     └── Calculator         — how much (flat $, %, per-item, etc.)
  └── PromotionCategory        — admin grouping

A promo can have multiple rules (ANDed or ORed via match_policy) and multiple actions (all fire when eligible).

Promotion attributes

Spree::Promotion.create!(
  name: 'Summer Sale 2026',
  code: 'SUMMER20',                 # required for the default kind: :coupon_code; pass kind: :automatic for no-code promos
  starts_at: Date.new(2026, 6, 1),
  expires_at: Date.new(2026, 9, 1),
  usage_limit: 1000,                # max total redemptions; nil = unlimited
  match_policy: 'all',              # 'all' (AND) or 'any' (OR) for rule matching
  advertise: true                   # show in store header / banners
)

• Coupon codes vs automatic: promotions have a kind enum — coupon_code (default) or automatic. Coupon-code promos require code (normalized to lowercase; matched case-insensitively). For promos that apply automatically when rules match, pass kind: :automatic — leaving code nil without it fails validation, since kind defaults to coupon_code.
• Per-customer limits: add a Spree::Promotion::Rules::OneUsePerUser rule. The customer must be logged in (anonymous orders can’t enforce per-customer limits — no identity).

Built-in PromotionRule subclasses

Each rule subclasses Spree::PromotionRule and implements eligible?(promotable, options = {}).

Rules combine via the promo’s match_policy:

• all — every rule must be eligible (default)
• any — at least one rule must be eligible

Built-in PromotionAction subclasses

Each action subclasses Spree::PromotionAction and implements perform(options = {}).

Discount actions consult a Calculator for the amount. Spree::Calculator::FlatRate gives a flat amount off; Spree::Calculator::PercentOnLineItem gives a percentage off matching items; Spree::Calculator::FlatPercentItemTotal gives a percentage off the cart total. The full calculator catalog lives at Spree::Calculator subclasses in spree_core/app/models/spree/calculator/.

Custom PromotionRule

Subclass Spree::PromotionRule, implement applicable? + eligible?, register in an initializer, add an admin partial:

# app/models/spree/promotion/rules/minimum_quantity.rb
module Spree
  class Promotion
    module Rules
      class MinimumQuantity < Spree::PromotionRule
        preference :quantity, :integer, default: 5

        def applicable?(promotable)
          promotable.is_a?(Spree::Order)
        end

        def eligible?(order, options = {})
          total_quantity = order.line_items.sum(&:quantity)
          return true if total_quantity >= preferred_quantity

          eligibility_errors.add(:base, "Order must contain at least #{preferred_quantity} items")
          false
        end
      end
    end
  end
end

# config/initializers/spree.rb
Rails.application.config.after_initialize do
  Spree.promotions.rules << Spree::Promotion::Rules::MinimumQuantity
end

# app/views/spree/admin/promotion_rules/forms/_minimum_quantity.html.erb
# The partial name must match the rule's `key` (`api_type` — demodulized, underscored class name by default).
# Action partials go in app/views/spree/admin/promotion_actions/forms/.
<div class="row mb-3">
  <%= f.spree_number_field :preferred_quantity, label: Spree.t(:minimum_quantity) %>
</div>

Add locale entries under spree.minimum_quantity and spree.promotion_rule_types.minimum_quantity.{name,description}. The admin selector reads from those keys.

Key methods on a rule

eligible? is called per-order during the cart pipeline. Keep it cheap — N+1 queries here are a common cart-pipeline performance issue.

Custom PromotionAction

Subclass Spree::PromotionAction and implement perform. Discount actions also include Spree::CalculatedAdjustments + Spree::AdjustmentSource:

# app/models/spree/promotion/actions/tiered_discount.rb
module Spree
  class Promotion
    module Actions
      class TieredDiscount < Spree::PromotionAction
        include Spree::CalculatedAdjustments
        include Spree::AdjustmentSource

        before_validation -> { self.calculator ||= Calculator::FlatRate.new }

        def perform(options = {})
          order = options[:order]
          return false unless order.present?

          create_unique_adjustment(order, order)
        end

        def compute_amount(order)
          discount = case order.item_total
                     when 100..Float::INFINITY then 25
                     when 50..99.99 then 10
                     else 0
                     end

          # Discounts are negative; cap to prevent negative orders
          [discount, order.item_total].min * -1
        end
      end
    end
  end
end

# config/initializers/spree.rb
Rails.application.config.after_initialize do
  Spree.promotions.actions << Spree::Promotion::Actions::TieredDiscount
end

Non-discount actions (award points, send notifications) don’t need the calculator includes — just implement perform.

Key methods on an action

perform runs during cart recalculate. Keep it cheap and idempotent — recalculate fires on many cart changes.

Helper methods from the includes

# Spree::AdjustmentSource:
create_unique_adjustment(order, adjustable)
create_unique_adjustments(order, order.line_items)
create_unique_adjustments(order, order.line_items) do |line_item|
  promotion.line_item_actionable?(order, line_item)
end

# Spree::CalculatedAdjustments:
compute(adjustable)                                # calls calculator.compute(adjustable)
self.calculator_type = 'Spree::Calculator::FlatRate'
self.class.calculators                              # available calculators

Custom Calculator

Calculators answer “given X, how much?” — the same calculator subclass can be used by multiple action types.

module Spree
  class Calculator::PercentWithCap < Spree::Calculator
    preference :percent, :decimal, default: 10
    preference :cap_amount, :decimal, default: 50

    def compute(object)
      base = object.amount.to_d
      raw = base * (preferred_percent / 100.0)
      [raw, preferred_cap_amount].min
    end
  end
end

Register so the action’s “available calculators” picker shows it:

Rails.application.config.after_initialize do
  Spree.calculators.promotion_actions_create_item_adjustments << Spree::Calculator::PercentWithCap
  # order-level actions read from Spree.calculators.promotion_actions_create_adjustments
end

Promotion stacking

Multiple promotions can each create adjustments, but Spree does not stack them on the same target. During recalculation Spree::Adjustable::Adjuster::Promotion (registered by default in Rails.application.config.spree.adjusters) keeps only the single best (largest-discount) eligible promo adjustment per adjustable — order, line item, or shipment — and marks competing promo adjustments eligible: false; on a tie the most recently created wins. Promotions targeting different adjustables can still combine (e.g. an order-level discount plus a line-item discount on the same order).

To change this behavior (e.g. allow stacking on one adjustable), swap in a custom adjuster via Rails.application.config.spree.adjusters.

Common promotion problems

“Promotion isn’t applying”

Walk this list:

1. Is the code right? Coupon codes are matched case-insensitively but must otherwise match exactly.
2. Within the window? promotion.starts_at < Time.current && (promotion.expires_at.nil? || promotion.expires_at > Time.current).
3. Usage limit not exceeded? promotion.usage_limit_exceeded?(order) should be false (nil limit = unlimited). To inspect manually, promotion.credits_count is the number of distinct orders that have used the promo — compare it against promotion.usage_limit when a limit is set.
4. Every rule eligible? With match_policy: 'all', every rule must return true. Walk promotion.rules.map { |r| [r.class.name, r.eligible?(order)] } to see which fails. Check r.eligibility_errors.full_messages for the reason.
5. Action ran during recalculate? Check order.all_adjustments.promotion — order.adjustments only holds order-level adjustments; CreateItemAdjustments writes to line items and FreeShipping to shipments. If empty, the action never fired — recalculate to retry.

“Custom rule isn’t showing in admin UI”

Confirm registration ran: Spree.promotions.rules.include?(Spree::Promotion::Rules::MyRule) should be true after Rails boot. Confirm the admin partial exists at app/views/spree/admin/promotion_rules/forms/_<key>.html.erb (the rule’s key / api_type). Confirm locale keys under spree.promotion_rule_types.<underscored_class>.{name,description} are present.

Where to read further

• Core concepts: node_modules/@spree/docs/dist/developer/core-concepts/promotions.mdx
• Custom rules + actions tutorial: node_modules/@spree/docs/dist/developer/how-to/custom-promotion.mdx
• Source: Spree::Promotion, Spree::PromotionRule, Spree::PromotionAction, Spree::Calculator in the installed spree_core gem
• Adjustments: see the spree-data-model skill — promotions create Adjustments tied to Orders, LineItems, or Shipments