> ## Documentation Index
> Fetch the complete documentation index at: https://api-docs.streamskill.pro/llms.txt
> Use this file to discover all available pages before exploring further.

# Data Modification

> Modify responses to fit your needs

### Content types

By default, the API returns a json response, but at the current time, we support the following response formats:

* `json` - The default response format.
* `xml` - The response in XML format.

For example, to request a response in XML format, you can add the `Accept` header to your request:

```http theme={null}
Accept: application/xml
```

### Response fields

You can specify which fields to return in the response by using the `fields` query parameter. This parameter accepts a comma-separated list of fields to include in the response.

For example, to return only the `id` and `name` fields in the response, you can use the following query parameter:

```http theme={null}
GET /purchases?fields=id,name
```

### Additional fields

You can also include additional fields in the response by using the `expand` query parameter. This parameter accepts a comma-separated list of fields to include in the response.

For example, to include the `tarif` field in the response, you can use the following query parameter:

```http theme={null}
GET /purchases?expand=tarif
```

<Note>
  You can combine the `fields` query parameter with the `expand` query parameter to receive attributes of related resources in the response.

  ```http theme={null}
  GET /purchases?expand=tarif&fields=id,tarif.id
  ```
</Note>