Add one-time product to subscription order

Adds a one-time product (add-on) to a specific subscription order. The product will be included only in the specified billing attempt and will not recur in future orders. This endpoint is idempotent - attempting to add the same product to the same billing attempt will return success without creating duplicates.

Full behavior, validation rules, and side effects

Important Behaviors:

• If the specified billingAttemptId is not valid or not QUEUED, the system will automatically add the product to the next upcoming order
• The system prevents duplicate products (same variantId) in the same billing attempt
• Products are automatically removed after the associated order is processed
• Activity logs are created for audit trails

Validation Rules:

• Contract must belong to the authenticated shop
• Contract must not be frozen (minimum cycles restriction)
• At least one QUEUED billing attempt must exist
• Variant must be a valid Shopify product variant

Use Cases:

• Allow customers to add special items to their next delivery
• Enable upselling opportunities in customer portals
• Programmatically add promotional or seasonal items
• Implement “try before you subscribe” features

Authentication: Requires valid X-API-Key header that identifies the shop

PUT /api/external/v2/subscription-contract-one-offs-by-contractId-and-billing-attempt-id

Add one-time product to subscription order

cURL

curl --request PUT \
  --url https://subscription-admin.appstle.com/api/external/v2/subscription-contract-one-offs-by-contractId-and-billing-attempt-id \
  --header 'X-API-Key: <x-api-key>'

200

Product Added Successfully

[
  {
    "id": 12345,
    "shop": "example-store.myshopify.com",
    "subscriptionContractId": 98765,
    "billingAttemptId": 54321,
    "variantId": 42549172011164,
    "variantHandle": "premium-coffee-blend-500g",
    "quantity": 2,
    "price": 19.99
  },
  {
    "id": 12350,
    "shop": "example-store.myshopify.com",
    "subscriptionContractId": 98765,
    "billingAttemptId": 54321,
    "variantId": 42549172011167,
    "variantHandle": "coffee-sampler-pack",
    "quantity": 1,
    "price": 29.99
  }
]

Headers

X-API-Key · string · required

API Key for authentication. This key identifies your shop and must be included in the X-API-Key header.

Query Parameters

api_key · string

API Key (Deprecated - Use X-API-Key header instead)

contractId · integer<int64> · required

The unique identifier of the subscription contract

Required range: x >= 1

billingAttemptId · integer<int64> · required

The billing attempt ID to add the product to. If invalid or not QUEUED, the system will automatically use the next upcoming order.

Required range: x >= 1

variantId · integer<int64> · required

The Shopify product variant ID to add as a one-time purchase

Required range: x >= 1

variantHandle · string · required

The handle/slug of the product variant for URL-friendly identification

Pattern: ^[a-z0-9]+(?:-[a-z0-9]+)*$

quantity · integer · default: 1

The quantity of the product to add. Defaults to 1 if not specified.

Required range: 1 <= x <= 999

Response

200

application/json

Successfully added one-time product or product already exists. Returns all one-time products for the contract.

shop · string · required

The Shopify store domain that owns this subscription

Pattern: ^[a-zA-Z0-9][a-zA-Z0-9-]*\.myshopify\.com$

Example:

"example-store.myshopify.com"

id · integer<int64> · read-only

Unique identifier of the one-time product record

Example:

12345

billingAttemptId · integer<int64>

The billing attempt ID this one-time product is associated with. This determines which upcoming order will include this product.

Required range: x >= 1

Example:

54321

subscriptionContractId · integer<int64>

The subscription contract ID this one-time product belongs to

Required range: x >= 1

Example:

98765

variantId · integer<int64>

The Shopify product variant ID for this one-time product

Required range: x >= 1

Example:

42549172011164

variantHandle · string

The handle/slug of the product variant for URL-friendly identification

Pattern: ^[a-z0-9]+(?:-[a-z0-9]+)*$

Example:

"premium-coffee-blend-500g"

quantity · integer<int32>

The quantity of this product to include in the order

Required range: 1 <= x <= 999

Example:

2

price · number<double>

The price per unit of this product in the shop's base currency. This may include any applicable discounts.

Required range: 0 <= x <= 999999.99

Example:

19.99