> ## Documentation Index > Fetch the complete documentation index at: https://developers.appstle.com/llms.txt > Use this file to discover all available pages before exploring further. # Add product line item to subscription contract > Adds a new product (line item) to an existing subscription contract. This allows customers or merchants to add products to their recurring subscription orders. **Key Features:** - **Add Products**: Include new products in future subscription deliveries - **Quantity Control**: Specify how many units of the product to add - **Price Override**: Set custom pricing for the added product - **Immediate Effect**: Changes apply to next billing cycle - **Activity Logging**: All additions are tracked in activity logs **Required Parameters:** - **contractId**: Subscription contract ID to modify - **variantId**: Shopify product variant ID (with gid:// prefix or numeric) - **quantity**: Number of units to add (must be positive integer) - **price**: Price per unit in shop's base currency **Product Variant ID Format:** Accepts two formats: - Shopify GID: `gid://shopify/ProductVariant/12345678901` - Numeric ID: `12345678901` **Price Behavior:** - Price is per unit, not total - Must be in shop's base currency (USD, EUR, etc.) - Can override product's default price - Does not include taxes or shipping - Total line item cost = price × quantity **Line Item Addition Rules:** - Product variant must exist in Shopify catalog - Product must be active and available - Variant must have sufficient inventory (if tracked) - Contract must be ACTIVE or PAUSED (not CANCELLED) - Cannot add duplicate variants (use update quantity instead) **Common Use Cases:** - Customer adds complementary product to existing subscription - Upsell additional products through customer portal - Merchant adds bonus items to customer subscriptions - Build custom "add-on" product selection interfaces - Cross-sell related products to existing subscribers - Create bundle upgrades (add multiple products at once) **Post-Addition Effects:** - Next billing amount increases by (price × quantity) - Product appears in all future subscription deliveries - Customer receives confirmation of subscription update - Activity log records the addition with source (portal/merchant) - Contract's next billing date remains unchanged **Integration Example:** ``` PUT /api/external/v2/subscription-contract-add-line-item? contractId=123456& variantId=gid://shopify/ProductVariant/987654321& quantity=2& price=19.99 ``` This adds 2 units of variant 987654321 at $19.99 each ($39.98 total) to contract 123456. **Important Notes:** - Changes apply to NEXT billing cycle, not current/past orders - If product is out of stock, order may be delayed or skipped - Price changes don't affect historical orders - Consider inventory availability before adding products **Authentication:** Requires API key authentication via X-API-Key header or api_key parameter ## OpenAPI ````yaml /memberships/admin-api-swagger.json put /api/external/v2/subscription-contract-add-line-item openapi: 3.0.1 info: description: >- Comprehensive API documentation for managing memberships, payments, and related operations. These APIs allow you to programmatically manage membership lifecycles, handle payments, configure products, and integrate membership functionality into your applications. title: Admin APIs version: 0.0.1 servers: - url: https://membership-admin.appstle.com security: [] tags: - description: >- APIs for managing Shopify delivery profiles, shipping rates, zones, and free shipping configuration for subscription memberships name: Shipping & Delivery Profiles - description: >- APIs for retrieving historical discount code usage and redemption information for membership contracts name: Customer Discount History - description: >- APIs for managing membership cancellation flow settings including retention offers, survey questions, and cancel confirmation screens name: Cancellation Flow Configuration - description: >- APIs for managing membership billing attempts, recurring orders, payment retries, order history, and order skipping name: Billing & Orders - description: >- APIs for managing one-time product additions to upcoming subscription orders, including adding, retrieving, and removing one-off items name: One-Time Add-Ons - description: >- APIs for managing membership/subscription plan groups, including creating plans, configuring discounts, billing intervals, and assigning products to plans name: Membership Plans - description: >- APIs for managing subscription product bundles, bundle configurations, item grouping, and bundle-specific discount codes name: Product Bundles - description: >- APIs for retrieving custom CSS styles applied to subscription widgets and customer portal for theme customization name: Custom CSS Styling - description: >- APIs for managing customer portal settings including UI customization, text labels, feature toggles, and branding options for the member self-service portal name: Customer Portal Configuration - description: >- APIs for managing membership/subscription contracts including creation, updates, status changes, line items, discounts, and billing operations name: Membership Contracts - description: >- APIs for managing subscription bundle configuration settings including bundle behavior, pricing rules, and display options name: Bundle Settings - description: >- APIs for managing customer payment methods, payment tokens, and payment method retrieval for subscriptions name: Customer Payment Methods - description: >- APIs for retrieving product swap/substitution options allowing members to exchange subscription items based on configured swap rules and variant groups name: Product Swap Rules - description: >- APIs for retrieving product catalog, variants, pricing, and inventory information for subscription memberships. name: Product & Inventory Data - description: >- APIs for managing shop-level membership settings, configuration, and general store information. name: Shop Settings - description: >- APIs for performing bulk/mass operations on multiple membership contracts including status updates, product replacements, and billing date changes. name: Bulk Operations paths: /api/external/v2/subscription-contract-add-line-item: put: tags: - Membership Contracts summary: Add product line item to subscription contract description: >- Adds a new product (line item) to an existing subscription contract. This allows customers or merchants to add products to their recurring subscription orders. **Key Features:** - **Add Products**: Include new products in future subscription deliveries - **Quantity Control**: Specify how many units of the product to add - **Price Override**: Set custom pricing for the added product - **Immediate Effect**: Changes apply to next billing cycle - **Activity Logging**: All additions are tracked in activity logs **Required Parameters:** - **contractId**: Subscription contract ID to modify - **variantId**: Shopify product variant ID (with gid:// prefix or numeric) - **quantity**: Number of units to add (must be positive integer) - **price**: Price per unit in shop's base currency **Product Variant ID Format:** Accepts two formats: - Shopify GID: `gid://shopify/ProductVariant/12345678901` - Numeric ID: `12345678901` **Price Behavior:** - Price is per unit, not total - Must be in shop's base currency (USD, EUR, etc.) - Can override product's default price - Does not include taxes or shipping - Total line item cost = price × quantity **Line Item Addition Rules:** - Product variant must exist in Shopify catalog - Product must be active and available - Variant must have sufficient inventory (if tracked) - Contract must be ACTIVE or PAUSED (not CANCELLED) - Cannot add duplicate variants (use update quantity instead) **Common Use Cases:** - Customer adds complementary product to existing subscription - Upsell additional products through customer portal - Merchant adds bonus items to customer subscriptions - Build custom "add-on" product selection interfaces - Cross-sell related products to existing subscribers - Create bundle upgrades (add multiple products at once) **Post-Addition Effects:** - Next billing amount increases by (price × quantity) - Product appears in all future subscription deliveries - Customer receives confirmation of subscription update - Activity log records the addition with source (portal/merchant) - Contract's next billing date remains unchanged **Integration Example:** ``` PUT /api/external/v2/subscription-contract-add-line-item? contractId=123456& variantId=gid://shopify/ProductVariant/987654321& quantity=2& price=19.99 ``` This adds 2 units of variant 987654321 at $19.99 each ($39.98 total) to contract 123456. **Important Notes:** - Changes apply to NEXT billing cycle, not current/past orders - If product is out of stock, order may be delayed or skipped - Price changes don't affect historical orders - Consider inventory availability before adding products **Authentication:** Requires API key authentication via X-API-Key header or api_key parameter operationId: addLineItemV2_1 parameters: - description: Subscription contract ID example: 12345 in: query name: contractId required: true schema: format: int64 type: integer - description: API Key (Deprecated - Use Header X-API-Key instead) in: query name: api_key required: false schema: type: string - in: header name: X-API-Key required: false schema: type: string - description: Quantity of product to add example: 2 in: query name: quantity required: true schema: format: int32 type: integer - description: Shopify product variant ID (with or without gid:// prefix) example: gid://shopify/ProductVariant/987654321 in: query name: variantId required: true schema: type: string - description: Price per unit in shop's base currency example: 19.99 in: query name: price required: true schema: format: double type: number responses: '200': content: application/json: schema: $ref: '#/components/schemas/SubscriptionContract' description: Line item successfully added to subscription contract '400': content: '*/*': schema: $ref: '#/components/schemas/SubscriptionContract' description: >- Invalid request - product not found, contract cancelled, or duplicate variant '401': content: '*/*': schema: $ref: '#/components/schemas/SubscriptionContract' description: Authentication required - invalid or missing API key '403': content: '*/*': schema: $ref: '#/components/schemas/SubscriptionContract' description: Forbidden - contract does not belong to authenticated shop '404': content: '*/*': schema: $ref: '#/components/schemas/SubscriptionContract' description: Subscription contract or product variant not found components: schemas: SubscriptionContract: properties: billingAttempts: $ref: '#/components/schemas/BillingAttempts' billingPolicy: $ref: '#/components/schemas/BillingPolicy' createdAt: type: object customAttributes: items: $ref: '#/components/schemas/CustomAttribute1' type: array customer: $ref: '#/components/schemas/Customer' customerPaymentMethod: $ref: '#/components/schemas/CustomerPaymentMethod' deliveryMethod: $ref: '#/components/schemas/DeliveryMethod' deliveryPolicy: $ref: '#/components/schemas/DeliveryPolicy' deliveryPrice: $ref: '#/components/schemas/DeliveryPrice' discounts: $ref: '#/components/schemas/Discounts' get__typename: type: string id: type: string lastPaymentStatus: enum: - SUCCEEDED - FAILED - $UNKNOWN type: string lines: $ref: '#/components/schemas/Lines' nextBillingDate: type: object note: type: string originOrder: $ref: '#/components/schemas/OriginOrder' status: enum: - ACTIVE - PAUSED - CANCELLED - EXPIRED - FAILED - $UNKNOWN type: string updatedAt: type: object type: object BillingAttempts: properties: get__typename: type: string nodes: items: $ref: '#/components/schemas/Node3' type: array type: object BillingPolicy: properties: anchors: items: $ref: '#/components/schemas/Anchor' type: array get__typename: type: string interval: enum: - DAY - WEEK - MONTH - YEAR - $UNKNOWN type: string intervalCount: format: int32 type: integer maxCycles: format: int32 type: integer minCycles: format: int32 type: integer type: object CustomAttribute1: properties: get__typename: type: string key: type: string value: type: string type: object Customer: properties: displayName: type: string email: deprecated: true type: string firstName: type: string get__typename: type: string id: type: string lastName: type: string phone: deprecated: true type: string type: object CustomerPaymentMethod: properties: get__typename: type: string id: type: string instrument: $ref: '#/components/schemas/Instrument' revokedAt: type: object revokedReason: enum: - AUTHORIZE_NET_GATEWAY_NOT_ENABLED - AUTHORIZE_NET_RETURNED_NO_PAYMENT_METHOD - FAILED_TO_UPDATE_CREDIT_CARD - STRIPE_API_AUTHENTICATION_ERROR - STRIPE_API_INVALID_REQUEST_ERROR - STRIPE_GATEWAY_NOT_ENABLED - STRIPE_RETURNED_NO_PAYMENT_METHOD - STRIPE_PAYMENT_METHOD_NOT_CARD - BRAINTREE_API_AUTHENTICATION_ERROR - BRAINTREE_GATEWAY_NOT_ENABLED - BRAINTREE_RETURNED_NO_PAYMENT_METHOD - BRAINTREE_PAYMENT_METHOD_NOT_CARD - PAYMENT_METHOD_VERIFICATION_FAILED - THREE_D_SECURE_FLOW_IN_VERIFICATION_NOT_IMPLEMENTED - MANUALLY_REVOKED - FAILED_TO_RETRIEVE_BILLING_ADDRESS - MERGED - CUSTOMER_REDACTED - TOO_MANY_CONSECUTIVE_FAILURES - CVV_ATTEMPTS_LIMIT_EXCEEDED - $UNKNOWN type: string type: object DeliveryMethod: properties: additionalInformation: $ref: '#/components/schemas/AdditionalInformation' brandedPromise: $ref: '#/components/schemas/BrandedPromise' get__typename: type: string id: type: string maxDeliveryDateTime: type: object methodType: enum: - SHIPPING - PICK_UP - NONE - RETAIL - LOCAL - PICKUP_POINT - $UNKNOWN type: string minDeliveryDateTime: type: object serviceCode: type: string type: object DeliveryPolicy: properties: anchors: items: $ref: '#/components/schemas/Anchor1' type: array get__typename: type: string interval: enum: - DAY - WEEK - MONTH - YEAR - $UNKNOWN type: string intervalCount: format: int32 type: integer type: object DeliveryPrice: properties: amount: type: object currencyCode: enum: - USD - EUR - GBP - CAD - AFN - ALL - DZD - AOA - ARS - AMD - AWG - AUD - BBD - AZN - BDT - BSD - BHD - BIF - BYN - BZD - BMD - BTN - BAM - BRL - BOB - BWP - BND - BGN - MMK - KHR - CVE - KYD - XAF - CLP - CNY - COP - KMF - CDF - CRC - HRK - CZK - DKK - DJF - DOP - XCD - EGP - ERN - ETB - FKP - XPF - FJD - GIP - GMD - GHS - GTQ - GYD - GEL - GNF - HTG - HNL - HKD - HUF - ISK - INR - IDR - ILS - IRR - IQD - JMD - JPY - JEP - JOD - KZT - KES - KID - KWD - KGS - LAK - LVL - LBP - LSL - LRD - LYD - LTL - MGA - MKD - MOP - MWK - MVR - MRU - MXN - MYR - MUR - MDL - MAD - MNT - MZN - NAD - NPR - ANG - NZD - NIO - NGN - NOK - OMR - PAB - PKR - PGK - PYG - PEN - PHP - PLN - QAR - RON - RUB - RWF - WST - SHP - SAR - RSD - SCR - SLL - SGD - SDG - SOS - SYP - ZAR - KRW - SSP - SBD - LKR - SRD - SZL - SEK - CHF - TWD - THB - TJS - TZS - TOP - TTD - TND - TRY - TMT - UGX - UAH - AED - UYU - UZS - VUV - VES - VND - XOF - YER - ZMW - USDC - BYR - STD - STN - VED - VEF - XXX - $UNKNOWN type: string get__typename: type: string type: object Discounts: properties: get__typename: type: string nodes: items: $ref: '#/components/schemas/Node2' type: array pageInfo: $ref: '#/components/schemas/PageInfo2' type: object Lines: properties: get__typename: type: string nodes: items: $ref: '#/components/schemas/Node' type: array pageInfo: $ref: '#/components/schemas/PageInfo' type: object OriginOrder: properties: fulfillmentOrders: $ref: '#/components/schemas/FulfillmentOrders' get__typename: type: string id: type: string name: type: string type: object Node3: properties: completedAt: type: object createdAt: type: object get__typename: type: string id: type: string idempotencyKey: type: string ready: deprecated: true type: boolean type: object Anchor: properties: cutoffDay: format: int32 type: integer day: format: int32 type: integer get__typename: type: string month: format: int32 type: integer type: enum: - WEEKDAY - MONTHDAY - YEARDAY - $UNKNOWN type: string type: object Instrument: properties: get__typename: type: string type: object AdditionalInformation: properties: get__typename: type: string instructions: type: string type: object BrandedPromise: properties: get__typename: type: string handle: type: string name: type: string type: object Anchor1: properties: cutoffDay: format: int32 type: integer day: format: int32 type: integer get__typename: type: string month: format: int32 type: integer type: enum: - WEEKDAY - MONTHDAY - YEARDAY - $UNKNOWN type: string type: object Node2: properties: createdAt: type: object deliveredAt: type: object displayStatus: enum: - ATTEMPTED_DELIVERY - CANCELED - CONFIRMED - DELAYED - DELIVERED - FAILURE - FULFILLED - CARRIER_PICKED_UP - IN_TRANSIT - LABEL_PRINTED - LABEL_PURCHASED - LABEL_VOIDED - MARKED_AS_FULFILLED - NOT_DELIVERED - OUT_FOR_DELIVERY - READY_FOR_PICKUP - PICKED_UP - SUBMITTED - $UNKNOWN type: string estimatedDeliveryAt: type: object get__typename: type: string id: type: string inTransitAt: type: object name: type: string requiresShipping: type: boolean service: $ref: '#/components/schemas/Service' status: enum: - PENDING - OPEN - SUCCESS - CANCELLED - ERROR - FAILURE - $UNKNOWN type: string trackingInfo: items: $ref: '#/components/schemas/TrackingInfo' type: array type: object PageInfo2: properties: endCursor: type: string get__typename: type: string hasNextPage: type: boolean hasPreviousPage: type: boolean startCursor: type: string type: object Node: properties: get__typename: type: string type: object PageInfo: properties: endCursor: type: string get__typename: type: string hasNextPage: type: boolean hasPreviousPage: type: boolean startCursor: type: string type: object FulfillmentOrders: properties: get__typename: type: string nodes: items: $ref: '#/components/schemas/Node' type: array pageInfo: $ref: '#/components/schemas/PageInfo2' type: object Service: properties: get__typename: type: string handle: type: string serviceName: type: string type: enum: - GIFT_CARD - MANUAL - THIRD_PARTY - $UNKNOWN type: string type: object TrackingInfo: properties: company: type: string get__typename: type: string number: type: string url: type: object type: object ````