> For the complete documentation index, see [llms.txt](https://docs.bookinglayer.com/api/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.bookinglayer.com/api/expanding-resources.md).

# Expanding Resources

Several objects support the retrieval of additional information through an expanded response by utilizing the `expand` request parameter. This parameter is applicable to most API requests and influences the response of the corresponding request.

In numerous scenarios, an object includes the ID of a correlated object within its response properties. For instance, a Booking has an associated Booker ID. You have the option to expand the Booker object using the **`expand`** request parameter. The **`expandable`** label in this documentation specifies ID fields that can be expanded into objects.

Example for <mark style="color:blue;">GET</mark> `/private/bookings/{id}`

```json
{
    "data": {
        "id": "ceba4275-479b-41a9-8a69-a4446ab693b9",
        "reference": "2023-3494",
        "starts_at": "2024-07-15 14:00:00",
        "ends_at": "2024-07-22 13:00:00",
        "status": "pending",
        "booker_id": "044fdd7d-22f8-4423-bac7-bb8fda345305",
        ...
    }
}
```

In `Booking` response you can always see **`booker_id`**. However, when you need more details about the **`Booker`** you can just expand by adding **`expand[]=booker`** to request query string.

Example for <mark style="color:blue;">GET</mark> `/private/bookings/{id}?expand[]=booker`

```json
{
    "data": {
        "id": "64938537-5947-40e8-8185-1042f16bf479",
        "reference": "2023-2494",
        "starts_at": "2024-07-15 14:00:00",
        "ends_at": "2024-07-22 13:00:00",
        "status": "pending",
        "booker_id": "ba03075f-ce2b-4003-ae36-4ed54d1f76a3",
        "booker": {
            "person": {
                "id": "ba03075f-ce2b-4003-ae36-4ed54d1f76a3",
                "first_name": "Henry",
                "last_name": "Smith",
                "initials": "HS",
                "gender": "male",
                "birth_date": null,
                "email": "inge.geelen@outlook.com",
                ...
            },
            "booking_related_data": {
                "tax_number": 2234567895,
                "company_name": "Bookinglayer",
                ...
            }
        }
    }
}
```

We **never expand** relations by **default**. Also one/many-to-many relations don't have arrays of foreign keys (ID's) in the default response. You have to explicitly expand then when it's needed. Example `Locations` in `Booking` resource.

```json
{
    "data": {
        "id": "ceba4275-479b-41a9-8a69-a4446ab693b9",
        "reference": "2023-3494",
        "reseller_reference": null,
        "is_connect": false,
        "starts_at": "2024-07-15 14:00:00",
        "ends_at": "2024-07-22 13:00:00",
        "status": "pending",
        ...
        "locations": [
            {
                "id": 1234,
                "backoffice_title": "Portugal",
                "title": "Portugal Algarve",
                "description": "...",
                "abbreviation": "POAL",
                "address": null,
                "zip_code": null,
                "city": null,
                "latitude": null,
                "longitude": null,
                "metadata": null,
                "deleted_at": null,
                "created_at": "2019-11-29T13:59:20+00:00",
                "updated_at": "2019-11-29T13:59:20+00:00",
            }
        ],
        ...
        "created_at": "2023-10-24T10:58:11+00:00",
        "updated_at": "2023-10-24T10:58:21+00:00"
    }
}

```

Recursive expansion is achieved by specifying nested fields after a dot (.) in the request. For instance, if you request `invoices.payments` on a **`Booking`**, it expands the `Booking` property with invoices lists and payments for those invoices.

You can use the expand parameter on any endpoint that returns expandable fields, including list, fetch single, create and update endpoints. Performing deep expansions on numerous list requests might result in slower processing times. Expansions have a maximum depth of three levels. You can expand multiple objects at the same time.