# Link a customer to a QuickBooks customer

```http
PUT https://secure.yoprint.com/v1/api/store/{team_slug}/customer/{hash_id}/external_id/{id}
```

- API version: v1
- Operation ID: `v1_public_customer_external_id_update`
- Section: Customers › [Customers](https://developer.yoprint.com/reference/customers.md)
- Web page: https://developer.yoprint.com/reference/customers/v1-customer-external-id-update/
- Authentication: `Authorization: Bearer YOUR_API_KEY`

Links this YoPrint customer to an existing QuickBooks Online customer, so YoPrint syncs it to that QuickBooks customer. YoPrint first looks the QuickBooks customer up, so it must exist. Answers `success: true` with `data: null`.

With `override_lock: true`, later syncs leave the QuickBooks customer's details alone instead of updating them from YoPrint.

## Permission

Any member of the team.

## Business rules

- The QuickBooks connection must be connected (not waiting to be reconnected).
- Customers synced from Shopify can't be linked to QuickBooks (422).

## Side effects

- Calls the QuickBooks Online API to read the customer, then saves the link.

## Path parameters

- `team_slug` (string, required): Your team slug, shown as Team ID next to your API key in Profile. Example `your-team`.
- `hash_id` (string, required): The customer's id (`id` from List customers or Create a customer). A hash id from an earlier answer; unique keys and document numbers (such as `PO0042`) don't work here. Example `EDhVUaC6jbLbed`.
- `id` (string, required): The QuickBooks Online connection's id (`id` from List integrations), not the QuickBooks record's Id. A hash id from an earlier answer; unique keys and document numbers (such as `PO0042`) don't work here. Example `uAu3dAKIaHyAYk`.

## Request body

Content type `application/json`, required.

Fields:

- `external_id` (string, required): The QuickBooks Online customer Id.
- `override_lock` (boolean, optional): True: never overwrite this QuickBooks customer from YoPrint. Defaults to false. Send a JSON boolean: it is stored as sent and read back as `override`.

### Example request

```bash
curl -X PUT 'https://secure.yoprint.com/v1/api/store/your-team/customer/EDhVUaC6jbLbed/external_id/uAu3dAKIaHyAYk' \
  -H 'Authorization: Bearer YOUR_API_KEY' \
  -H 'Accept: application/json' \
  -H 'X-Yoprint-Decimal-Format: exact-v1' \
  -H 'Content-Type: application/json' \
  -d '{
    "external_id": "58",
    "override_lock": false
  }'
```

## Response

`200` Successful response.

Fields:

- `data` (null, required)
- `status` (integer, required)
- `success` (boolean, required)

Example response:

```json
{
  "data": null,
  "status": 200,
  "success": true
}
```

## Errors

- `401` The API key is missing or wrong (`unauthenticated`).
- `403` You are not allowed to do this. `api_access_not_in_plan`: your team's plan doesn't include API access (Pro and above, with an active subscription or trial), so every request answers this until the team upgrades. When your role lacks the permission the operation needs, the body is only `{"message": "Insufficient Permission"}`. Other refusals use the error envelope, with `unauthorized` or `user_is_not_authorized`.
- `404` Not found. `page_not_found`: the team slug is unknown, you are not a member of the team, or an id in the path is not one of this team's. `code: null`, with a message that starts "No query results for": there is no record with that id.
  - When: No customer, or no integration, with these ids. `error.code` is null and `error.message` names the record type. Fix: Check both ids.
- `422` The request was refused and changed nothing. `validation_failed` lists what to fix in `error.fields`; other codes name a business rule, explained in `error.message`. A few checks answer with only `{"message": "..."}`. An operation that calls another service (a payment provider, a carrier, an accounting app) can answer `connect_timeout` ("Please retry again") when that service does not answer in time: the change may or may not have happened there, so read the record back before you retry.
  - When: `external_id` is missing, or `override_lock` is not a boolean. `error.code` is `validation_failed`. Fix: Send `external_id`.
  - When: `{id}` is an integration but not QuickBooks Online (`error.code` `unable_save_external_id`), or the customer is synced from Shopify (`validation_error`). Fix: Use the QuickBooks connection's id.
  - When: QuickBooks has no customer with this Id (`error.code` `validation_error`, "Cannot find corresponding  QuickBook Online resource :Customer"). Fix: Check the QuickBooks customer Id.
  - When: The QuickBooks Online connection can't be used: it is waiting to be reconnected (`error.code` `auth_error`), or its sign-in expired, QuickBooks refused it or QuickBooks could not be reached (`bootstrap_error`, with the reason in `error.message`). Fix: Reconnect QuickBooks Online under Apps, or retry later.

## Notes

- Deleted customers can be linked too.

## Related

- [Get the QuickBooks customer linked to a customer](https://developer.yoprint.com/reference/customers/v1-customer-external-id-get.md): `GET /v1/api/store/{team_slug}/customer/{hash_id}/external_id/{id}`
- [Unlink a customer from QuickBooks](https://developer.yoprint.com/reference/customers/v1-customer-external-id-delete.md): `DELETE /v1/api/store/{team_slug}/customer/{hash_id}/external_id/{id}`