# Update a Customer

As we have already seen, we can update a resource with POST request that includes both:

- the correct version number
- an array of update actions

For multi-language SDK code snippets for updating Customers, see [SDK example code](https://docs.commercetools.com/learning-composable-commerce-developer-essentials/dev-tooling/sdk-example-code.md#add-a-customer-name).

To update a resource in commercetools, you provide the `id` or `key` to identify the resource to update, and the current `version` number with a list of update actions. Versions only exist in the created resource and not the draft payload.

Update actions are a way to explicitly define what changes to make to a resource, without needing to send the whole resource body (including fields that will not change). Here are the [Customer update actions](https://docs.commercetools.com/api/projects/customers.md#update-actions):

Image url: https://docs.commercetools.com/learning-composable-commerce-developer-essentials/images/manage-resources-with-the-sdk/customers-update-actions.png Alt text: The docs list all the update actions for the Customer resource.

In the following example, we assign the Customer to a Customer Group. We identify the Customer Group with the following `key`: `vip-customer-group`.

Make sure to create the Customer Group before running the code (you can do this in the Merchant Center) and that you provide the correct `version` number in your update actions.

As with creating a Customer, the Java SDK makes heavy use of the builder pattern. We use this pattern to construct the update action and the reference to the Customer Group.

In the TypeScript SDK, you must build the correct structure yourself. However, it is quite interesting how similar both programming languages are in all our exercises.

## Use the SDKs

Create a file called `customerUpdateGroup.js` and copy the following code:

```typescript
import { apiRoot } from '../impl/apiClient.js';

const customerKey = 'jon-doe-customer';
const customerGroupId = 'vip-customer-group';

// Change the version number if necessary
const customerVersion = 1;

async function customerUpdateGroup(customerKey, customerGroupId, version) {
  try {
    const response = await apiRoot
      .customers()
      .withKey({ key: customerKey })
      .post({
        body: {
          version: version,
          actions: [
            {
              action: 'setCustomerGroup',
              customerGroup: { key: customerGroupId },
            },
          ],
        },
      })
      .execute();

    console.log('Success', JSON.stringify(response.body, null, 2));
  } catch (error) {
    console.log(JSON.stringify(error, null, 2));
  }
}

customerUpdateGroup(customerKey, customerGroupId, customerVersion);
```

In the following code we have combined the code snippets from the service and exercise class. Make sure you place the code into the correct files and add import statements as needed.

```java
CustomerService:
public CompletableFuture<ApiHttpResponse<Customer>> assignCustomerToCustomerGroup(long version, String customerKey, String customerGroupKey) {
    return
        apiRoot
          .customers()
          .withKey(customer.getKey())
          .post(CustomerUpdateBuilder.of()
              .version(version())
              .actions(
                  CustomerSetCustomerGroupActionBuilder.of()
                    .customerGroup(CustomerGroupResourceIdentifierBuilder.of()
                        .key(customerGroup.getKey())
                        .build()
                    )
                    .build()
                )
              .build()
            )
          .execute();
}

CustomerExercise:
logger.info("Customer assigned to group: " +
    customerService
        .assignCustomerToCustomerGroup(
            1L, "jon-doe-customer", "vip-customer-group"
        )
        .toCompletableFuture().get()
        .getBody().getEmail()
);
```

In production, fetch the current version before updating. We hardcoded it in this case to keep the code concise.

## Response

Let's first verify that the Customer has been added to the correct Customer Group.

We can check this in the Merchant Center and confirm that John Doe is now a member of `vip-customer-group`.

Image url: https://docs.commercetools.com/learning-composable-commerce-developer-essentials/images/manage-resources-with-the-sdk/customer-group-updated.png Alt text: Customer Group added successfully to the Customer.

## Another example

Let’s look at another example. Here we will add a new address to a Customer's address list. Adding a new address to the Customer's address list uses the [`addAddress` update action](https://docs.commercetools.com/api/projects/customers.md#add-address) which requires providing information about the address. Check the documentation to understand what fields can be set for this action.

```bash
POST  https://api.{region}.commercetools.com/{projectKey}/customers/{id}
Authorization: Bearer my_token
Content-Type: application/json

{
  "version" : 3,
  "actions" : [ {
    "action" : "addAddress",
    "address" : {
      "streetName" : "Easy St",
      "streetNumber" : "1",
      "postalCode" : "3427",
      "city" : "Diggers Rest",
      "country" : "AU"
    }
  } ]
}

```

Here is how it would look in Postman:

Image url: https://docs.commercetools.com/learning-composable-commerce-developer-essentials/images/manage-resources-with-the-sdk/postman.png Alt text: Postman update action.

In this example we are adding the address without a `key`. If we send multiple `addAddress` requests with the correct version and the same address, commercetools will create duplicates of the address, each with a unique `id`. This is because we have not set a `key` as a unique identifier.

If we set the address including a `key` and try to add multiple addresses with the same `key`, then we will get a helpful error: `The given address with 'key' {key-used} is already present in the Customer.` and no duplicates will be created.

Throughout your Project, using well designed `key`s is very important to create and manage resources.

Now check your Customer in your commercetools Project. You will find the new address has been added to the Customer's addresses.

## Related pages

- [Section overview page](https://docs.commercetools.com/learning-composable-commerce-developer-essentials.md)
- [Previous page: Get a Customer](https://docs.commercetools.com/learning-composable-commerce-developer-essentials/manage-resources-with-the-sdk/get-a-customer.md)
- [Next page: Delete a Customer](https://docs.commercetools.com/learning-composable-commerce-developer-essentials/manage-resources-with-the-sdk/delete-a-customer.md)