Add a product to an existing membership contract

Adds a new product/variant line item to an existing active membership contract. This allows customers or merchants to add additional products to their recurring membership orders.

Full behavior, validation rules, and side effects

Key Features:

• Add any product variant to an existing membership
• Specify custom quantity and price per line item
• Product will be included in all future billing cycles
• Price is per-item, total line price = price × quantity

Important Notes:

• Immediate Effect: Product is added immediately and will appear in the next billing cycle
• Price Override: The price parameter allows setting a custom price (e.g., member discount)
• Activity Logging: Addition is logged for audit trail
• Validation: System validates that the variant exists and is available

Common Use Cases:

• Customer wants to add more products to their monthly membership box
• Merchant adds a complimentary product to a membership
• Upgrading membership with additional items
• Adding seasonal or limited-time products to existing memberships

Price Considerations:

• Price is specified in shop’s currency
• Can be set to member-only pricing (different from regular product price)
• Zero price is allowed for free add-ons

Variant ID Format:

• Accepts both numeric ID (e.g., ‘987654321’) and Shopify GID format
• System will convert to proper Shopify GraphQL format internally

Authentication: Requires authenticated shop user or customer portal token

PUT /memberships/cp/api/subscription-contracts-add-line-item

Add a product to an existing membership contract

cURL

curl --request PUT \
  --url https://www.myshop.com/apps/memberships/cp/api/subscription-contracts-add-line-item

200

Example

{
  "get__typename": "<string>",
  "id": "<string>",
  "createdAt": {},
  "updatedAt": {},
  "nextBillingDate": {},
  "deliveryPrice": {
    "get__typename": "<string>",
    "amount": {}
  },
  "billingPolicy": {
    "get__typename": "<string>",
    "intervalCount": 123,
    "anchors": [
      {
        "get__typename": "<string>",
        "cutoffDay": 123,
        "day": 123,
        "month": 123
      }
    ],
    "maxCycles": 123,
    "minCycles": 123
  },
  "deliveryPolicy": {
    "get__typename": "<string>",
    "intervalCount": 123,
    "anchors": [
      {
        "get__typename": "<string>",
        "cutoffDay": 123,
        "day": 123,
        "month": 123
      }
    ]
  },
  "lines": {
    "get__typename": "<string>",
    "nodes": [
      {
        "get__typename": "<string>",
        "id": "<string>",
        "sellingPlanId": "<string>",
        "sellingPlanName": "<string>",
        "productId": "<string>",
        "sku": "<string>",
        "title": "<string>",
        "variantId": "<string>",
        "quantity": 123,
        "customAttributes": [
          {
            "get__typename": "<string>",
            "key": "<string>",
            "value": "<string>"
          }
        ],
        "lineDiscountedPrice": {
          "get__typename": "<string>",
          "amount": {}
        },
        "variantImage": {
          "get__typename": "<string>",
          "transformedSrc": {}
        },
        "variantTitle": "<string>",
        "currentPrice": {
          "get__typename": "<string>",
          "amount": {}
        },
        "discountAllocations": [
          {
            "get__typename": "<string>",
            "amount": {
              "get__typename": "<string>",
              "amount": {}
            },
            "discount": {
              "get__typename": "<string>"
            }
          }
        ],
        "pricingPolicy": {
          "get__typename": "<string>",
          "basePrice": {
            "get__typename": "<string>",
            "amount": {}
          },
          "cycleDiscounts": [
            {
              "get__typename": "<string>",
              "afterCycle": 123,
              "computedPrice": {
                "get__typename": "<string>",
                "amount": {}
              },
              "adjustmentValue": {
                "get__typename": "<string>"
              }
            }
          ]
        },
        "taxable": true
      }
    ],
    "pageInfo": {
      "get__typename": "<string>",
      "hasPreviousPage": true,
      "hasNextPage": true,
      "startCursor": "<string>",
      "endCursor": "<string>"
    }
  },
  "customerPaymentMethod": {
    "get__typename": "<string>",
    "id": "<string>",
    "instrument": {
      "get__typename": "<string>"
    },
    "revokedAt": {}
  },
  "deliveryMethod": {
    "get__typename": "<string>"
  },
  "originOrder": {
    "get__typename": "<string>",
    "id": "<string>",
    "name": "<string>",
    "fulfillmentOrders": {
      "get__typename": "<string>",
      "nodes": [
        {
          "get__typename": "<string>",
          "fulfillAt": {},
          "id": "<string>"
        }
      ],
      "pageInfo": {
        "get__typename": "<string>",
        "hasPreviousPage": true,
        "hasNextPage": true,
        "startCursor": "<string>",
        "endCursor": "<string>"
      }
    }
  },
  "customer": {
    "get__typename": "<string>",
    "id": "<string>",
    "email": "<string>",
    "displayName": "<string>",
    "firstName": "<string>",
    "lastName": "<string>",
    "phone": "<string>"
  },
  "discounts": {
    "get__typename": "<string>",
    "nodes": [
      {
        "get__typename": "<string>",
        "id": "<string>",
        "title": "<string>",
        "value": {
          "get__typename": "<string>"
        },
        "recurringCycleLimit": 123,
        "usageCount": 123
      }
    ],
    "pageInfo": {
      "get__typename": "<string>",
      "hasPreviousPage": true,
      "hasNextPage": true,
      "startCursor": "<string>",
      "endCursor": "<string>"
    }
  },
  "note": "<string>",
  "customAttributes": [
    {
      "get__typename": "<string>",
      "key": "<string>",
      "value": "<string>"
    }
  ],
  "billingAttempts": {
    "get__typename": "<string>",
    "nodes": [
      {
        "get__typename": "<string>",
        "completedAt": {},
        "createdAt": {},
        "id": "<string>",
        "idempotencyKey": "<string>",
        "ready": true
      }
    ]
  }
}

Query Parameters

contractId · integer<int64> · required

Membership contract ID to add product to

shop · string · required

Shop domain (will be auto-populated from authentication)

quantity · integer<int32> · required

Quantity of the product to add

variantId · string · required

Shopify variant ID of the product to add (numeric or GID format)

price · number<double> · required

Price per unit in shop currency (allows custom/member pricing)

Response

200

application/json

Product successfully added to membership contract

get__typename · string

id · string

createdAt · object

updatedAt · object

nextBillingDate · object

status · enum<string>

Available options: ACTIVE, PAUSED, CANCELLED, EXPIRED, FAILED, $UNKNOWN

deliveryPrice · object

Show child attributes

lastPaymentStatus · enum<string>

Available options: SUCCEEDED, FAILED, $UNKNOWN

billingPolicy · object

Show child attributes

deliveryPolicy · object

Show child attributes

lines · object

Show child attributes

customerPaymentMethod · object

Show child attributes

deliveryMethod · object

Show child attributes

originOrder · object

Show child attributes

customer · object

Show child attributes

discounts · object

Show child attributes

note · string

customAttributes · object[]

Show child attributes

billingAttempts · object

Show child attributes