> ## Documentation Index > Fetch the complete documentation index at: https://developer.fabric.inc/llms.txt > Use this file to discover all available pages before exploring further. # Update customer > Updates the customer information in the cart. The Cart ID from the [Create cart](/v3/cart-and-checkout/api-reference/carts-v3/carts/carts) endpoint is used in the path parameter. ## OpenAPI ````yaml modular-cart patch /carts/{cartId}/customer openapi: 3.0.1 info: title: Cart API description: >- fabric's **Cart API** lets you add, update, and remove items from your Storefront cart, either as a guest user or as a logged-in user. It also provides functionality to merge carts when you switch from guest user to logged-in user, and apply coupons and other attributes (for example, gift wrapping) to the line items. Additionally, the API supports more advanced tasks such as using multiple carts within a B2B organization, sharing carts, and supporting a unified cart experience for multi-region and multi-brand businesses.

The Cart API provides high performance, scalability, multi-tenancy, and configurability to the end-to-end order processing actions that start from the item being added to the cart; through the pre-checkout stage that includes billing, shipping, and payment details; to the checkout stage where the order is processed and confirmed by fabric's Order Management System (OMS) contact: name: Cart Support email: support.cnc@fabric.inc license: name: fabric API License url: https://fabric.inc/api-license version: 3.0.0 servers: - url: https://api.fabric.inc/v3 security: - bearerAuth: [] tags: - name: Cart description: >- Cart endpoints are used to do basic cart operations, such as create a cart, add item to the corresponding cart, update items, remove items, delete cart, update status of the cart, and more. - name: Items description: Item endpoints are used to add, update and remove items from the Cart. - name: Cart Fees description: >- Cart fee endpoints are used to add, update and remove fees at the Cart level. - name: Fulfillment Fees description: >- Fulfillment fees endpoints are used to add, update and remove fees at the Fulfillment level. - name: Addresses description: >- Address endpoints are used to add add, update and remove addresses from the Cart. - name: Item Fees description: >- Item fee endpoints are used to add, update and remove fees at the Item level. - name: Cart Adjustments description: >- Cart adjustment endpoints are used to add, update and remove adjustments at the Cart level. - name: Payments description: >- Payments endpoints are used to add add, update and remove payments from the Cart. - name: Customer description: >- Customer endpoints are used do basic customer operations, such as update a customer, add attributes and more. - name: Coupons description: Coupon endpoints are used to add and remove coupons from the Cart - name: Item Adjustments description: >- Item adjustments endpoints are used to add, update and remove adjustments at the Item level. - name: Fulfillment Adjustments description: >- Fulfillment adjustments endpoints are used to add, update and remove adjustments at the Fulfillment level. - name: Fulfillments description: >- Fulfillment endpoints are used to add add, update and remove fulfillments from the Cart. - name: Validations description: >- Validation endpoints are used to pass in data from fabric and third-party services to perform business logic on the Cart paths: /carts/{cartId}/customer: patch: tags: - Customer summary: Update customer description: > Updates the customer information in the cart. The Cart ID from the [Create cart](/v3/cart-and-checkout/api-reference/carts-v3/carts/carts) endpoint is used in the path parameter. operationId: updateCustomer parameters: - name: cartId in: path required: true schema: type: string description: >- The 24-character system-generated Cart ID. This ID is generated using the [Create cart](/v3/cart-and-checkout/api-reference/carts-v3/carts/carts) endpoint. - name: x-fabric-tenant-id in: header description: > A header used by fabric to identify the tenant making the request. You must include tenant id in the authentication header for an API request to access any of fabric’s endpoints. You can retrieve the tenant id , which is also called account id, from [Copilot](/v3/platform/settings/account-details/getting-the-account-id). This header is required. required: true schema: type: string example: 617329dfd5288b0011332311 - name: x-fabric-request-id in: header description: ' Unique request ID for tracking.' required: false schema: type: string example: 263e731c-45c8-11ed-b878-0242ac120002 - name: x-fabric-channel-id in: header description: >- x-fabric-channel-id identifies the sales channel through which the API request is being made; primarily for multichannel use cases. It is a required field. The default US channel is 12 while the default Canada channel is 11. required: false schema: type: string example: '12' requestBody: content: application/json: schema: $ref: '#/components/schemas/CustomerContextRequest' required: true responses: '200': description: OK content: application/json: schema: $ref: '#/components/schemas/CustomerContextResponse' '400': description: Client error content: application/json: schema: $ref: '#/components/schemas/ClientError' '404': description: Cart not found content: application/json: schema: $ref: '#/components/schemas/NotFound' components: schemas: CustomerContextRequest: type: object properties: id: type: string description: >- This is where you can include non-system-generated Customer ID. Since there is no validation for duplicate Customer IDs, ensure each ID is unique to each customer. example: '109840938' attributes: type: object additionalProperties: type: object description: Customer attributes such as email. example: email: test@gmail.com description: Customer attributes such as email. example: email: test@gmail.com segments: type: array description: An array containing customer segments. items: $ref: '#/components/schemas/SegmentRequest' sessionId: type: string description: Session ID example: 3a5fd2d3-5c96-4e57-b069-7ff2a88c1119 description: Customer Context Request CustomerContextResponse: type: object properties: id: type: string description: >- The Customer ID that was added to the customer attribute when using this endpoint. example: '109840938' attributes: type: object additionalProperties: type: object description: Customer attributes such as email. example: email: test@gmail.com description: Customer attributes such as email. example: email: test@gmail.com segments: type: array description: An array containing customer segments. items: $ref: '#/components/schemas/SegmentRequest' sessionId: type: string description: Session ID example: 3a5fd2d3-5c96-4e57-b069-7ff2a88c1119 ClientError: type: object properties: type: type: string description: Error code, meant for machine consumption example: BAD_REQUEST message: type: string description: Human-readable error description example: x-fabric-tenant-id is required description: Client error details NotFound: type: object properties: type: type: string description: Error code, meant for machine consumption example: CART_NOT_FOUND message: type: string description: Human-readable error description example: Cart not found description: Resource Not Found SegmentRequest: required: - name - value type: object properties: name: type: string description: >- Segment name such as a membmership the customer has with the merchant. example: membership value: type: array description: Segment values such as membership type. example: - gold - silver items: type: string description: Segment values example: '["gold","silver"]' description: Segment Request securitySchemes: bearerAuth: type: http scheme: bearer bearerFormat: JWT description: > This is the authorization token used to authenticate the request. You must pass the access token generated from the system app. For more information, see the [Making your first API request](/v3/api-reference/getting-started/getting-started-with-fabric-apis#procedure) section. ````